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THE USE OF LOCAL FEED INGREDIENTS IN THE CULTURE of the FRESHWATER PRAWN
Macrobrachium rosenbergii in FIJI
by
Temalesi Koroi
A thesis submitted in partial fulfilment of the
requirements for the degree of
Masters of Science in Marine Science
Copyright © 2012 by Temalesi Koroi
School of Marine Studies
Faculty of Science, Technology and Environment
The University of South Pacific
September, 2012
i
Acknowledgement
I would like to acknowledge the Almighty God for the strength, wisdom, knowledge
and understanding throughout the duration of my study for without His guidance I
would not have made it this far.
I express my gratitude to my sponsor, Australian Centre for International
Agricultural Research (ACIAR) for financial assistance and providing the
opportunity to complete my studies for a Masters degree. Also thank the ACIAR
collaborators of this project Dr. Satya Nandlal, Dr. David Hurwood and Professor
Peter Mather for allowing me to work on this project with them “Freshwater prawn
aquaculture in the Pacific region: improving culture stock and nutrition in Fiji”.
Special appreciation to my supervisor Dr. William N. Camargo at the University of
the South Pacific (USP) and Dr. Carmen Gonzalez at Queensland University of
Technology (QUT) for their encouragement, support and believing in me to conduct
the research. The valuable advice, comments and criticisms has enhanced the quality
of this thesis. I am grateful to your availability, dedication and efforts. In addition,
my sincere thanks also to the administration staff of USP. I wish to complement Dr.
Simon Hodge for his assistance with statistical analysis. I am grateful to Dr Azam
Khairul for his encouragement, support, time and efforts in editing of the thesis for
final submission.
I sincerely acknowledge all the staff of Fiji Fisheries Department based at
Naduruloulou Aquaculture Research Station for the provision of post larvae and
juvenile prawns, facility and ponds for the research. Much appreciation to Mr. Jone
Vasuca, Fiji project Officer for the tremendous help and dedication of his time in
assisting me with sampling and technical advice. Also my thanks to Tebara Halal
Meats Prawn Farm for provision of juvenile prawns.
I am indebted to my parents’ Mr. and Mrs. Koroi, Pauline, Akeai Jr. and friends
Shalini Singh, Monal Lal, and Avinesh Singh for their continuous support, love and
encouragement throughout the research for the past two years.
Vinaka Vakalevu.
ii
Abstract
A nutrition study was conducted to evaluate the growth performance, survival rate,
feed intake, proximate and cost analysis of feeds for freshwater prawn
(Macrobrachium rosenbergii) using low cost diets made with ingredients locally
available in Fiji. This study was divided into two phases. Phase I (Experiment 1 &
2), which was ingredient inclusion experiments was carried out in 18 (6 treatments x
3 replicates) one-hundred L aquaria in a closed recirculation system. Experiment 1
tested varying inclusion levels of fish-FM, meat-bone-MBM and meat-fish meal-
MFM. Experiment 2 tested varying inclusion levels of wheat-WHT, mill mix-MM,
copra-CP and pea meal-PM. Phase II (Experiment 3), was carried out in 12-earthen
ponds (4 treatments x 3 replicates) for 124 days, testing two experimental low-cost
feed formulations using FM, MBM, WHT, CP and PM against two commercially
available feeds (Crest Tilapia and Pacific Prawn). The level of inclusion of
ingredients in Experiments 1 & 2 did not show any significant difference (P≤ 0.05) in
growth performance, survival rate and feed intake of the freshwater prawn M.
rosenbergii. This suggests that inclusion levels for feeds formulation of diets for
freshwater prawn M .rosenbergii could be quite flexible. The 124 days pond
experiment showed overall no statistically significant differences (P≤ 0.05) for
growth performance, survival rate and feed intake of prawns. In terms of value, Diet
1 showed slightly higher weight gain (9.28 ± 0.42 g), slightly higher SGR (2.25 ±
0.01 %/ day) and lowest and best FCR value of 0.97±0.02 compared to Diet 2 and
the two commercial feeds. Survival rates ranged between 83.05 ± 3.22 and 88.84 ±
0.48 with slightly higher survival value seen in prawns fed experimental Diet 2
compared to Diet 1 and two commercial feeds. Further comparing the two
commercial feeds, Pacific Prawn feed showed better values of weight gain (8.87 ±
0.65 g), SGR (2.21 ± 0.02 %/day) and FCR (1.09 ± 0.02). The study showed that it
cost FJ$1.05 to produce 1 kg of prawn by Diet 1 which was cheaper when compared
to the commercial diets Pacific Prawn feed (FJ$1.66) and Crest Tilapia feed
(FJ$1.34). The investigation indicated that M. rosenbergii growth, survival rate and
feed intake was slightly better with experimental Diet 1 containing 44.5 % fish meal,
5.0 % copra meal, 5.0 % pea meal, 43.5 % wheat and 2.0 % vitamin-mineral premix.
Based on growth, yield and feed cost it may be suggested that this Diet 1 could be
further tested in a pilot study before suggested to be used commercially for
monoculture of M. rosenbergii in ponds in Fiji.
iii
Abbreviation
ABW- Average Body Weight
ACIAR- Australian Centre for International Agricultural Research
A/E- essential amino acid /total essential amino acid
Ag- Silver
AOAC- Association of Analytical Communities
As- Arsenic
cal/g- calories per gram
Cd- Cadmium
CP- Copra
Cr- Chromium
CTP- Crest Tilapia Pellet
DFF- Dairy Farms Fiji
DFR- Daily Feed Ration
D.O- Dissolved Oxygen
EEA- Essential Amino Acid
F- Fluorine
FAO- Food and Agriculture Organization of the United Nations
FCR- Food Conversion Ratio
FM- Fish Meal
FMF- Flour Meals of Fiji
FMIB- Fiji Meat Industry Board
FTIB- Fiji Trade and Investment Board
FSC- Fiji Sugar Corporation
GFP- Giant Freshwater Prawn
GLC- Gas Liquid Chromatography
HUFA- Highly Unsaturated Fatty Acid
IU- International Unit
JICA- Japan International Co-operation Agency
kcal- kilocalories
iv
kJ- kiloJoules
MBM- Meat Bone Meal
MFM- Meat Fish Meal
mg- milligram
MM- Meat Meal
MPI- Ministry of Primary Industry
MT- Metric tones
NRS- Naduruloulou Research Station
PAFCO- Pacific Fishing Company
Pb- Lead
PIC- Pacific Island Countries
PER- Protein Energy Ratio
PL- post larvae
PM- Pea Meal
PPP- Pacific Prawn Pellet
QUT Queensland University of Technology
Sc- Scandium
SGR- Specific Growth Rate
SPC- Secretariat of the Pacific Community
t- time
TFR- Total Feed Requirement
USP- University of the South Pacific
WG- Weight Gain
WHT- Wheat
v
Table of Contents
Acknowledgements ................................................................................................... i Abstract ..................................................................................................................... ii Abbreviations ............................................................................................................ iii Table of Contents ...................................................................................................... v List of Tables............................................................................................................. vii List of Figures ........................................................................................................... xi List of Plates .............................................................................................................. xi
1.0 INTRODUCTION ............................................................................................. 1 1.1Global production of freshwater prawns .............................................................. 1 1.2 Feeds ................................................................................................................... 6 1.3 Demand and availability of feed resources ......................................................... 7 1.4 Finding alternative sources of feed ingredient .................................................... 9 1.5 Aqua feed and the environment .......................................................................... 10 1.6 Quality control of feeds ....................................................................................... 11 1.7 Feeding trials in Fiji ............................................................................................ 12 1.8 Research objectives ............................................................................................. 13 1.9 Thesis Overview.................................................................................................. 14 2.0 LITERATURE REVIEW ................................................................................. 15 2.1 Dietary requirements of M. rosenbergii .............................................................. 15 2.2 Assessment of Feed Ingredients .......................................................................... 19 2.3 Feed Formulation and Development ................................................................... 23 2.4 Feed Ingredient Analysis .................................................................................... 24 2.5 Grow out feeds .................................................................................................... 25 2.5.1 Farm- made feeds ....................................................................................... 27 2.5.2 Commercial feeds....................................................................................... 28 2.6 Water parameters ................................................................................................ 28 3.0 MATERIALS AND METHODS ..................................................................... 30 3.1 Experiments in aquarium- Assessment of ingredient inclusion levels ............... 30 3.1.1 Experimental set up .................................................................................... 30 3.1.2 Local ingredients ........................................................................................ 30 3.1.3 Formulation and feed preparation .............................................................. 31 3.1.4 Stocking in aquaria tanks ........................................................................... 33 3.1.5 Feeding and data collection ........................................................................ 33 3.2 Experiment in grow out ponds- comparison between experimental formulations and commercial feeds ................................................................................. 34 3.2.1 Experimental set up .................................................................................... 34 3.2.2 Formulation and feed preparation .............................................................. 34 3.2.3 Pond preparation and stocking ................................................................... 35 3.2.4 Feeding and data collection ........................................................................ 36 3.2.5 Water quality parameters ........................................................................... 36 3.2.6 Calculations ............................................................................................... 36 3.2.6.1 Growth performance, survival rate and feed intake .......................... 36 3.2.6.2 Production costs ................................................................................ 37 3.2.7 Statistical Analysis………………………………………………………..37
vi
4.0 RESULTS AND DISCUSSIONS…………………………………………….. 38
4.1 Experiments in aquarium- Assessment of ingredient inclusion levels……… 38 4.1.1 Experiment 1…………………………………………………………………. 38 4.1.1.1 Proximate analysis………………………………………………………..38 4.1.1.2 Growth performance, survival rate and feed intake……………………… 39 4.1.1.3 Water quality parameters…………………………………………………... 42 4.1.2 Experiment 2………………………………………………………………… 42 4.1.2.1 Proximate analysis………………………………………………………… 42 4.1.2.2 Growth performance, survival rate and feed intake…………………….. 44 4.1.2.3 Water quality parameters………………………………………………….. 46 4.1.3 Experiment in grow out ponds- comparison between experimental formulations and commercial feeds ...……………………………………. 47 4.1.3.1 Proximate analysis…………………………………………………………. 47 4.1.3.2 Growth performance, survival rate and feed intake……………………… 47 4.1.3.3 Pond Production: Experimental feed vs. Commercial feed……………… 50 4.1.3.4 Production cost: experimental vs. commercial feed……………………... 52 4.1.3.5 Water Quality Parameters………………………………………………….. 54 5.0 CONCLUSIONS AND RECOMMENDATIONS………………………… .. 55 6.0 REFERENCES……………………………………………………………… .. 56 7.0 ANNEXES…………………………………………………………………… .. 69
vii
List of Tables
Table 1. Major 10 producing countries of commercial aqua feed in 2008............. 7 Table 2. Nutrient requirements of the giant freshwater prawn M. rosenbergii...... 16 Table 3. Reported proximate analysis for selected ingredients used in compound
aqua feeds................................................................................................. 23
Table 4. Raw ingredients and suppliers in Fiji....................................................... 30 Table 5. Formulation (%) of the diets based on different inclusion levels tested
on M. rosenbergii juveniles (Experiment 2)....................................... 31
Table 6. Formulation (%) of the diets based on different inclusion levels tested on M. rosenbergii juveniles (Experiment 1)............................................
32
Table 7. Formulation of Crest Tilapia Pellet (Experiment 2.................................. 32 Table 8. Pond dimensions and stocking density for the M. rosenbergii pond
nutrition experiment conducted for 124 d............................................. 34
Table 9. Formulation (%) of experimental grow-out diets for M. rosenbergii pond grow-out trial for 124 d. (Experiment 3)......................................
35
Table 10. Proximate composition of experimental diets (Experiment 1)................. 38 Table 11. Proximate composition of experimental ingredients (Experiment 1)....... 38 Table 12. Mean growth performance, survival and feed intake of M. rosenbergii
fed six different diets of varying inclusion levels of meat bone meal and meat fish meal for 21 d.............................................................
41
Table 13. Average water temperature and dissolved oxygen different diets for 21 d.................................................................................................
42
Table 14. Proximate composition of ingredients (Experiment2)............................. 43 Table 15. Proximate composition of experimental diets (Experiment 2)................. 43 Table 16. Mean growth performance, survival and feed intake of M. rosenbergii
fed four different diets for 28 d........................................................ 45
Table 17. Average temperature and dissolved oxygen for M. rosenbergii fed six diets for 28 d (Experiment 2)............................................................
46
Table 18. Proximate compositions of experimental diets and commercial diets (Experiment 3)..............................................................................
47
Table 19. Mean growth and feed utilization for M. rosenbergii fed four different experimental diets in a pond experiment conducted for 124 d (Experiment 3)......................................................................
49
Table 20. Comparison of experimental feed and commercial feed for M. rosenbergii pond nutrition experiment conducted for 124d (Experiment 3)......................................................................
53
Table 21. Water quality values monitored during the M. rosenbergii pond nutrition experiment conducted for 124 d (Experiment 3).......................
54
Table 22. Experiment 1 single factor ANOVA of weight gain of M.rosenbergii.... 74 Table 23. Experiment 1 single factor ANOVA of specific growth rate for
M.rosenbergii.......................................................................................... 74
Table 24. Experiment 1 single factor ANOVA of carapace length gain for M. rosenbergii...............................................................................................
74
Table 25. Experiment 1 single factor ANOVA of abdomen length gain for M. rosenbergii...............................................................................................
74
Table 26. Experiment 1 single factor ANOVA of total body length gain for M .rosenbergii..............................................................................................
74
Table 27. Experiment 1 single factor ANOVA of survival for M. rosenbergii........ 74 Table 28. Experiment 1 single factor ANOVA of food consumed for
M.rosenebrgii.......................................................................................... 75
viii
Table 29. Experiment 1 single factor ANOVA of temperature for M.rosenbergii..........................................................................................
75
Table 30. Experiment 1 single factor ANOVA of dissolved oxygen for M. rosenbergii................................................................................................
75
Table 31. Experiment 2 single factor ANOVA of weight gain for M. rosenbergii..........................................................................................
75
Table 32. Experiment 2 single factor ANOVA of specific growth rate for M. rosenbergii................................................................................................
75
Table 33. Experiment 2 single factor ANOVA of carapace length gain for M .rosenbergii...............................................................................................
75
Table 34. Experiment 2 single factor ANOVA of abdomen length gain for M .rosenbergii...............................................................................................
76
Table 35. Experiment 2 single factor ANOVA of total body length for M. rosenbergii................................................................................................
76
Table 36. Experiment 2 single factor ANOVA of Survival for M. rosenbergii................................................................................................
76
Table 37. Experiment 2 single factor ANOVA of food consumed for M. rosenbergii...............................................................................................
76
Table 38. Experiment 2 single factor ANOVA of temperature for M. rosenbergii.........................................................................................
76
Table 39. Experiment 2 single factor ANOVA of dissolved oxygen for M. rosenbergii..............................................................................................
76
Table 40. Experiment 3 single factor ANOVA of weight gain for M. rosenbergii........................................................................................
80
Table 41. Experiment 3 single factor ANOVA of total feed intake for M. rosenbergii..............................................................................................
80
Table 42. Experiment 3 single factor ANOVA of feed intake per animal for M .rosenbergii.............................................................................................
80
Table 43. Experiment 3 single factor ANOVA of protein intake for M. rosenbergii.............................................................................................
80
Table 44. Experiment 3 single factor ANOVA of protein intake per animal for M. rosenbergii..................................................................................
80
Table 45. Experiment 3 single factor ANOVA specific growth rate for M. rosenbergii..............................................................................................
81
Table 46. Experiment 3 single factor ANOVA of feed conversion ratio for M. rosenbergii..............................................................................................
81
Table 47. Experiment 3 single factor ANOVA of protein energy ratio for M.rosenbergii.........................................................................................
81
Table 48. Experiment 3 single factor ANOVA of survival for M.rosenbergii........................................................................................
81
Table 49. Experiment 3 single factor ANOVA of temperature for M.rosenbergii..........................................................................................
81
Table 50. Experiment 3 single factor ANOVA of dissolved oxygen for M.rosenbergii.............................................................................
82
Table 51. Experiment 3 single factor ANOVA of pH for M. rosenbergii.............. 82 Table 52. Crest Feed Mill Freshwater Prawn Formulation..................................... 82 Table 53. Crest Feed Mill Proximate Analysis of Freshwater Prawn Pellet........... 82 Table 54. Crest Feed Mill Proximate Composition of Tilapia Grower Pellet......... 82
ix
List of Figures
Figure 1. Production (t) of the farmed giant river prawn Macrobrachium rosenbergii in the major producing countries.................................
2
Figure 2. Annual value of aquaculture production in the South Pacific in USD thousands...............................................................................
2
Figure 3. Estimated global aqua feed production in 2008 for major farmed species....................................................................
6
Figure 4. Estimated use of fish meal (percentage of dry feed basis) within aqua feeds in 2008...................................................................
8
Figure 5. Estimated use of fish oil (percentage of dry feed basis) in 2008....... 8 Figure 6. Mean weight gain, total body length gain and for M. rosenbergii
fed six different diets for 21 d (Experiment 1).............................. 39
Figure 7. Average food consumption of M. rosenbergii fed six different protein level diets over 21d (Experiment 1)..................................
72
Figure 8. Specific growth rate of the M. rosenbergii fed six different diets for 21 d (Experiment 1)...................................................................
40
Figure 9. Average water quality parameter for feed intake over 21 d (Experiment 1).....................................................................
72
Figure 10. Mean weight gain, total body length gain and survival of M. rosenbergii fed six different diets for 28 d (Experiment 2)........
44
Figure 11. Average food consumption of prawns fed six different diets over 28 d (Experiment 2).......................................................
73
Figure 12. Specific growth rate of M. rosenbergii fed six different diets for 28 d (Experiment 2)................................................
46
Figure 13. Average water quality parameters measured for the feed intake trial over 28 d.........................................................
73
Figure 14. Feed conversion ratio for M. rosenbergii fed four different diets in the pond experiment conducted for 124 d (Experiment 3)..............
50
Figure 15. Average weight M. rosenbergii fed four different diets in the pond experiment conducted for 124 d (Experiment 3)...........................
51
x
List of Plates Plate 1: Experimental Set up of recirculation system in the .................................... 69 Wet Lab at USP Plate 2: Sieving ingredient ...................................................................................... 69 Plate 3: Weighing ingredients ................................................................................. 69 Plate 4: Combining ingredients ............................................................................... 69 Plate 5: Mixing ingredients with water ................................................................... 69 Plate 6: Diet through passes pellet machine ............................................................ 70 Plate 7: Dried pellets .............................................................................................. 70 Plate 8: Diets stored in plastic bags ......................................................................... 70 Plate 9: Separated Diet rations ................................................................................ 70 Plate 10: Weighing out daily ration.......................................................................... 70 Plate 11: Vacuum Filtration apparatus ..................................................................... 70 Plate 12: Filtered uneaten feed ................................................................................. 71 Plate 13: Uneaten feed wrapped in foil .................................................................... 71 Plate 14: Re-weighing prawn ................................................................................... 71 Plate 15: Measuring carapace length ........................................................................ 71 Plate 16: Measuring abdomen length ....................................................................... 71 Plate 17: Grinding ingredients ................................................................................. 77 Plate 18: Weighing out ingredients .......................................................................... 77 Plate 19: Mixing ingredients .................................................................................... 77 Plate 20: Pelletizing diets ......................................................................................... 77 Plate 21: Drying feeds in oven ................................................................................. 77 Plate 22: Packed feeds for storage............................................................................ 77 Plate 23: Quarantine Facility .................................................................................... 78 Plate 24: Raceway used for stocking PL .................................................................. 78 Plate 25: Post larvae at PL 14................................................................................... 78 Plate 26: Feed tray in raceway ................................................................................. 78 Plate 27: Complete pond draining ............................................................................ 78 Plate 28: Pond Liming .............................................................................................. 79 Plate 29: Earthen ponds filled with water ................................................................ 79 Plate 30: Counting of PL .......................................................................................... 79 Plate 31: PL stocking in ponds ................................................................................. 79
1
1.0 INTRODUCTION
1.1 Global production of freshwater prawns
Aquaculture has been traditionally practiced in a few countries for centuries. In a
global perspective, this food producing sector being quite young has during the past
50 years grown rapidly (FAO, 2010). In 2008, crustacean production stood at 5.0
MT. World production of crustaceans was distributed evenly among brackish water
(2.4 MT or 47.7 percent), freshwater (1.9 MT or 28.2 percent) and marine water (0.7
MT or 14.1 percent) (FAO, 2010). The rapid increase in crustacean production is the
result of the increase in white leg shrimp culture in China, Thailand and Indonesia.
The global production of the giant fresh water prawn (Macrobrachium rosenbergii)
in 2007 as stated in FAO, 2009b was over 221,000 t which is 2.7 times greater than a
decade earlier (Fig. 1). Since 1995 rapid expansion of aquaculture for all freshwater
prawn faming species has been attributed to the huge production of China at 41.3 MT
or 69.6 percent and 21.9 percent produced from the rest of the Asia and Pacific
region (FAO, 2006). The other major producing countries of M. rosenbergii are
India, Thailand, Bangladesh, Taiwan and Vietnam. It is anticipated that global
aquaculture will continue to increase mainly in developing countries in South East
Asia. The increase in production in developing countries is likely to be achieved
through growth of semi-intensive, small scale pond aquaculture. Due to its
commercial importance in the aquaculture industry, M. rosenbergii has become the
world’s largest most studied freshwater prawn (FAO, 2002). Under culture, the
prawns show a wide range of temperature and salinity tolerance, accepting a large
range of formulated diets and compatible with non-predaceous species of fish in
culture, has a relatively short larval life and fast growing. Fast growing individuals
reach market size in about 7–8 months, and the meat is of high quality in terms of
taste and texture (FAO, 2002).
2
Figure 1. Production (t) of the farmed giant river prawn Macrobrachium
rosenbergii in the major producing countries (Source: FAO, 2009b).
Aquaculture in the Pacific is currently worth US$ 211 thousand with an increasing
harvested value since 1998 of US$ 1.89 billion (Fig. 2) (Ponia, 2010). Fiji and
French Polynesia are the main crustacean producers apart from New Caledonia.
Figure 2. Annual value of aquaculture production in the South Pacific in
USD thousands (Source: Ponia, 2010).
Following pearls, crustacean are the second most valuable commodity in the Pacific
Island Countries (PIC) worth US$31 million in 2007 (Ponia, 2010). This was
contributed mainly from marine shrimps and some minor contribution from
freshwater species. Farmed crustacean species include: giant tiger shrimp (Penaeus
monodon), blue shrimp (Liptopenaeus stylirostris), white shrimp (Litopenaeus
vannamei), giant freshwater prawn (Macrobrachium rosenbergii), monkey river
prawn (M. lar) and red crawfish (Cherax quadricarinatus). New shrimp farms in
Vanuatu, Northern Mariana Islands and Guam have also contributed to peak
production of 204 t worth 2.7 million in 2007 (Ponia, 2010).
0
50000
100000
150000
200000
250000
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Prod
uctio
n (T
onne
s)
Year
Global total
Bangladesh
China
India
Taiwan
Thailand
Vietnam
Others
0
50,000
100,000
150,000
200,000
250,000
1998 1999 2000 2001 2002 2003 2004 2005 2006 2007
Val
ue (U
SD th
ousa
nd)
Year
3
Fiji has a strong domestic market demand (approx. 700 tons/yr) for shrimp (retail
price US$ 14 to 17/kg), but only 150 tons can presently be provided by local sources
and the remainder is imported from overseas (Pickering and Chim, 2007). Currently,
Fiji imports over 70 percent of shrimps for local consumption with total imports
estimated to be around 600 metric tons valued at approximately FJ$ 15.2 million
annually from Australia and Solomon Islands to mainly feed our hotel industry
(FTIB, 2009). Farm gate prices of M. rosenbergii prawns have decreased to FJ$20
per kg and $25per kg for retail. However aquaculture in Fiji only accounts for less
than 10 percent of the value of all fishery exports and this is expected to increase
(FTIB, 2009).
In Fiji, the aquaculture industry has taken a long time to develop with commercial
scale aquaculture only developing about 50 years ago (Pickering and Forbes, 2002).
Since 1980, Fiji government policy has encouraged and highlights the protection of
coastal fisheries resources, thus developing aquaculture to meet the increasing
demand for fish and aquatic products (Gonzalez and Allan, 2007). Aquatic animal
protein demand in Fiji is mainly met by imports from various countries and a
relatively small domestic production.
According to the Fisheries Department inventory report for the year 2010, there are
currently 196 farmers (mostly fish farmers) in the Central Division including
Naitasiri, Tailevu and Rewa, with Tailevu Province showing the greatest number
(MPI, 2010). The majority of the farmers depend on the provision of prawn / fish
seedlings from the Government hatcheries, while other farmers living inland source a
few seedlings (mostly M. lar) from the wild. According to the report, about 31
percent of the farmers are operating at subsistence level, 83 percent semi-commercial
and 1 percent as commercial. The data provided reveals that the majority (88
percent) of the farms are culturing tilapia compared to other species including
prawns (8 percent), goldfish (1 percent) and grass carp (3 percent) (MPI, 2010).
Further, the same report indicated that farmers felt that commercial feed was too
costly. In addition, the inconsistent supply of prawn seedlings is hindering the
development of the very promising prawn industry.
Freshwater prawns were first introduced in Fiji in 1982 with the assistance of the
Japan International Cooperation Agency (JICA) (Takano, 1987), for a project that
sought the production of post-larvae that was based in Naduruloulou Research
4
Station (NRS) to try and successfully spawn M. rosenbergii. The spawning success
has contributed to the development of freshwater aquaculture in Fiji and other Pacific
nations.
In 2011, four hatcheries were operational, two owned by the Department of Fisheries
(NRS and Galoa Research Station-production in the latter was very low in 2011), a
third one at the School of Marine Studies (University of the South Pacific - USP) and
a one at Tebara Halal Meats Navua prawn farm (W. Camargo, pers. comm., 2011).
Both Fisheries Research stations NRS and Galoa have been providing assistance by
supplying extension services and free of charge PL’s (irregular production
fluctuating from 400,000 to 1 million PL’s/yr in the last 3 years) mainly to small
scale farmers (with 1 or 2 ponds of 0.1 ha) around the country. However, both
hatcheries have the capacity to produce well over 5 million PLs annually, which
could easily be utilized by the existing number of prawn farmers (W. Camargo, pers.
comm., 2011). PL production has been compromised over the years, mainly due to
inconsistent management practices, lack of resources allocated to this hatchery and
administrative issues.
The giant freshwater prawn hatchery at the University of the South Pacific started its
commercial operation in 2003. In October 2005 through a contract between USP’s
Institute of Marine Resources (IMR) and Dairy Farms of Fiji (DFF, the largest, 24
pond, prawn farm in Fiji, owned by Viti Corp, a Fiji Government failed rice farm
provided technical support, training and supplied prawn PL’s during Phase 1(W.
Camargo, pers. comm., 2011). Subsequently, in Phase 2, DFF took over management
while USP continued to supply PL’s and offered technical advice up to December
2010 after which DFF was leased to Tebara Halal Meats. During 2010 USP produced
about 150,000 PL’s/yr (FJ$ 40/1000 PL), before production stopped due to
difficulties faced in the hatchery (W. Camargo, pers. comm., 2011). In late 2010, the
hatchery relocated to the Navua prawn farm. Currently in Fiji, freshwater prawns are
mono-cultured and are harvested 4-5 months after stocking with PLs. Freshwater
prawn farming was initially concentrated in the Central part of the main island with
12 operational farms where farmers practiced semi-commercial level of farming
(MPI, 2010). However, recent increase in demand for prawns has attracted many
farmers to venture into prawn farming.
5
A limited number of ingredients are used in the formulation of feeds used in semi-
intensive aquaculture in Fiji. Tuna is imported from Taiwan and Japan to process
into canned fish. Two sub-products are produced after processing: fish meal and
meat and fish meal. According to chemical analysis provided by a technician at
Pacific Fishing Company (PAFCO) Ltd, the protein level is 52 percent. Both fish and
meat products are priced at FJ$0.80/kg and production of 76,850 MT of 300-400
bags of 45 kg each (ACIAR, 2008). At the time of study, fish meal and meat fish
meal was available for use in the diets, however due to the closure of PAFCO Ltd in
2010, the production of commercial freshwater prawn feed and tilapia feeds have
also declined and eventually ceased. Another company Voko Industries Ltd in Suva
import jack mackerel from New Zealand for canning. Production is around 5-8
tons/day whereby 65 percent of fish is canned and the remaining 35 percent is
discarded in amounts of 16.5 ton/day. This company however, does not produce fish
meal anymore (ACIAR, 2008).
Fiji Meat Industry Board (FMIB) abattoir in Nasinu produces for cattle, pig, ship and
goat and as a sub-product produce meat bone meal. This product costs FJ$0.76 and
analysis obtained from the company show the product to contain 48 % crude protein
content (ACIAR, 2008).
Carlton brewery in Walu Bay produces two by products in the brewery process
including brewery grains (8-10 ton/day) and yeast which is free at 3 tons every 3
weeks. These two products were not used in the diet formulation as the proximate
analysis values of these products were not favorable to be used in the diets (ACIAR,
2008).
Fiji Sugar Corporation (FSC) Ltd in Lautoka produces bagasse and molasses as by-
products from the sugar mill. However, due to the drop in sugarcane production from
4-2.5 ton/year, and since the products are being used in ethanol production,
availability and supply for use in the study was not consistent (ACIAR, 2008).
Evergreen Rice Mill in Navua and Rewa Rice Ltd in Dreketi mills imported rice
from Thailand. Evergreen Rice produces two sub products of rice bran and broken
rice with an average production between 2.5-6.3 ton/month at prices of FJ$0.60 and
0.33 respectively. Rewa Rice produces 3 tons of pollard rice, broken rice and rice
husk at prices FJ$0.28, 0.40 and 0.04 respectively (ACIAR, 2008).
6
Flour Mills of Fiji (FMF) produces mill mix, rice bran and pea mill as sub-products
of milling. Production is continuous at 84 ton of mill mix and 12 ton/day of rice bran
and pea meal daily. Prices at mill mix FJ$0.31 and rice bran and pea mill at FJ$0.56.
(ACIAR, 2008).
1.2 Feeds
Feed is the major operational cost for most aquaculture enterprises accounting for
over 50 percent of the production cost (FAO, 2009c). Lack of appropriate resources
has contributed to low productivity mainly due to unavailability of supplementary
feeds. Furthermore, commercial feeds may be available but expensive for small scale
farmers. There is a need to continue to produce and refine fertilizers and feed
resources. In most developed countries, cultured fish or crustaceans are reared
utilizing industrially compound feeds. Industrially manufactured feeds are readily
available in most countries including Chile, Brazil, Mexico, Costa Rica and
Colombia producing salmon, shrimp, tilapia and trout feeds (Fig. 3) (FAO, 2009c).
Figure 3. Estimated global aqua feed production in 2008 for major farmed
species (Source: Tacon, 2010).
Since 1995, compound aqua feed production has increased by 284 percent with a
total estimated production in 2008 to be 29.3 MT (Tacon, 2010). If growth is to be
sustained then feed ingredient and feed input supply must grow at a similar rate.
The top ten country producers of commercial aqua feeds in 2008 are China, Vietnam,
Thailand, Norway, Indonesia, Chile, USA, Japan, Philippines and Taiwan (Table 1).
According to Tacon (2010), industrial compound aqua feed production was 24.4 -
28.9 MT whereby 4 percent of total global animal production over 708 MT in 2009.
Fed carp31%
Shrimp17%Tilaipia
14%
Catfish10%
Marine fish8%
Salmon7%
FW Crustaceans
5%
Trout3%
Milkfish2%
Misc FW fish2%
Eels1%
7
However, there is no complete information on the production of farm-made feeds or
use of low–value fish. Estimates in 2006 showed global farm made aqua feeds at
18.7-30.7 MT (Tacon, 2010).
Table 1. Major 10 producing countries of commercial aqua feed in 2008
Country Production estimate (tones) China 13,000,000 – 15,000,000 Vietnam 1,625,000 – 2,800,000 Thailand 1,210,327 – 1,445,829 Norway 1,136,800 – 1,382,000 Indonesia 1030,000 – 1184,500 Chile 883,305 – 1,050,000 USA 700,000 – 750,000 Japan 500,000 Philippines 400,000 – 450,000 Taiwan 345,054
(Source: Tacon, 2010).
1.3 Demand and availability of feed resources
All finfish and crustacean farming systems depend on the market availability of feed
resources for providing nutrients either in the form of fertilizers, agricultural wastes
and byproducts, fishery wastes and by-products, supplementary feed mixers or
formulated pelleted aqua feeds (Tacon, 1998).
High quality fishmeal and fish oil are the major dietary ingredients in formulated
feeds. According to SEAFISH (2010), the world annual production of fish meal has
varied between 4.8 and 6.2 MT for the past 5 years with the main producing
countries in 2008 being Peru, Chile, Thailand, USA, Japan, Denmark, China, Iceland
and Norway. World fish oil production stands at 1.0 MT produced from 23.0 MT of
whole fish and trimmings (SEAFISH, 2010). Fish meal used as protein source for
diets for some finfish and crustacean species are still at levels in excess of 50 percent
(Glencross et. al., 2007).
Due to limited world supply of fish meal and increasing prices, much effort has been
put into evaluating a wide range of potential alternatives to fish meal and fish oils
such as plant or terrestrial animal origin for use in aquaculture diets for M.
rosenbergii. According to Tacon (2010), it was estimated that the aquaculture sector
consumed over 4.66 MT of fish meal and fish oil in 2007. However, he stated that
there is a wide variation in fishmeal and fish oil usage between major producing
countries for individual species (Figs. 4 and 5).
8
Figure 4. Estimated use of fish meal (percentage of dry feed basis) within aqua feeds in 2008 (Source:
Tacon, 2010).
The reliance of fish meal by the aquaculture industry in the long term is expected to
decrease. According to Tacon (2010), it is expected that the fishmeal usage fall to 3.6
MT which is 5.2 percent of total aqua feeds production in 2020. This is due to the use
of more raw materials being used for direct human consumption and increasing
fishmeal prices (Tacon, 2010). However, it will be expected that this decrease in
usage of fish meal will increase the use of less expensive, and ideally more
digestible, fish meal replacers. The use of fish oil as direct human supplements or
pharmaceutical medicines is also in growing demand whereby these markets are able
to pay a premium for oil thus reducing their use in aquaculture (Tacon, 2010).
Furthermore, reducing fish oil availability means restricting inclusion levels in diets.
Although this may not have a negative effect on the health of the farmed animal, it
may reduce health benefits of final products to consumers.
Figure 5. Estimated use of fish oil (percentage of dry feed basis) in 2008 (Source: Tacon, 2010).
0200400600800
10001200
Met
ric to
nnes
(mt)
050
100150200250300350
Met
ric to
nnes
(mt)
9
1.4 Finding alternative sources of feed ingredients
Another area of research in aquaculture nutrition is the use of plant and animal by-
products as fish meal substitutes. Fish meal has been the protein source of choice in aqua
feeds mainly because of its high protein content, excellent amino acid profile, high
nutrient digestibility, general lack of anti-nutrients, relative low price and its wide
availability (FAO, 2009c). However, due to increased cost of energy as a result of high
petroleum prices, El Niño effects, and increasing demand have resulted in a global
increase in fishmeal price (FAO, 2009c). In semi-intensive farming system, high cost of
these ingredients has restricted their use. The world price for fishmeal ranged between
US$ 500 and 700 per tonne during the period 2000–2005. In May 2008, the price of
fishmeal was US$ 1,210 per tonne (FAO, 2009c).
Replacing fish meal with plant by-products does not generally give desired growth
performances, however more research should emphasize on the proper utilization of
these ingredients as supplemental feed rather than as substitutes for fishmeal (De Silva,
1993). The replacement of fish meal with plant protein sources is limited by the fact that
plant proteins contain anti-nutritional factors (e.g. soya beans). Many plant and animal
protein sources have been identified by Tacon (FAO, 1994) as fishmeal replacers. These
include: invertebrate animal by-products (e.g., silkworm pupae, earthworms, and
zooplankton), vertebrate animal by-products (e.g., blood meal, liver meal, meat and bone
meal, poultry by-products), single-cell proteins (mainly from fungal and bacterial
sources), oilseeds (e.g., soybean, rapeseed, sunflower and cotton seed), legumes (e.g.,
beans, peas, lupins) and miscellaneous plant products (e.g., corn gluten meal and
concentrates made from potatoes and leaves). According to Tacon (2010), oil seed
production in 2008 was 427 MT with soybean being the largest and fastest growing oil
seed crop of 231 MT. Using different protein sources in various combinations is more
effective than that of a single source, thus preventing high inclusion level of any single
anti-nutrient in the diet (Hossain and Jauncey, 1990).
According to New (2001), poor digestibility, low availability of some essential amino
acids, palatability problems and presence of anti-nutritional factors have limited the
replacement of fishmeal by plant proteins. In addition, the inclusion of supplemental
10
(synthetic) amino acids and flavor enhancers has improved these factors. More recently,
the use of enzymes to enhance the nutritional value of diets based on plant proteins has
been suggested and according to Gerin (1999) ‘used on a commercial basis in aqua
feeds’.
The replacement of fish oils has been a more challenging task due to the difficulty in
finding alternative sources of omega-3 molecules. Fish oil has been replaced by
vegetable oils with preference to those with high omega-3 contents such as soya, canola,
palm and poultry oil (Tacon, 2010). Other alternatives include single cell proteins such
as algae, yeast and bacteria with high highly unsaturated fatty acid content. These
alternatives however, are expensive for most aquaculture feeds.
However, due to rising prices of both fish meal and fish oil, research in the feed industry
is being driven towards finding substitutes likely to shift feeding and feeding
compositions thus utilizing non-marine sourced feed ingredients (particularly
slaughterhouse wastes, brewery wastes and agriculture milling by-products). Rendered
animal proteins are very valuable for formulating cost effective, low fish meal
aquaculture feeds. The high digestible protein and energy contents of most rendered
animal protein ingredients makes them useful for formulation of low fishmeal, high
nutrient density fish feeds. A large number of studies have shown that the quality of
these ingredients had improved over the past two to three decades (Nates and Bureau,
2009).
1.5 Aqua feed and the environment
Generally, it is agreed that fish are to be fed more environmentally friendly diets,
developing better feeding strategies and proper farm management. The challenge for
developed countries using intensive farming systems where all species mainly depend on
nutritionally complete diets is to produce environmentally pleasant diets.
Potential pollutants from aqua feed are phosphorous, nitrogen and organic matter
(Alvarado, 1997). For example, the flux of nutrients from a gilthead sea bream farm
under intensive production fed commercially extruded diets released 180 kg of solid, 13
kg phosphorous and 105 kg nitrogen in the environment by uneaten feed to produce
11
1000 kg of fish (Alvarado, 1997). A Possible solution is to make diets with low Feed
Conversion Ratio (FCR) by improving palatability and digestibility of raw ingredients.
Producing fish meal and fish oil from marine fish in aquaculture can contribute to the
damaging of ecosystems due to conflict between uses for aqua feeds and for human
consumption (Glencross et. al., 2007). Furthermore, the use of agriculture by-products to
make feeds for aquatic farmed animals will have to compete with other users (i.e.
humans and/or farm livestock) for these feed resources.
1.6 Quality control of feeds
The quality of compound animal feeds is based on the quality of its constituents i.e. raw
materials used to formulate the feed (Uppal, 2002). Poor quality feeds results in poor
appetite, development of diseases, slow growth, high feed conversion ratio and low
survival (Cruz, 1994). Maintaining quality of raw materials must be ensured by
evaluation beginning with safe collection, processing, and use of efficient quality control
systems. For example, meat and bone meal are two animal by-products used as
substitutes for fish meal around the world, thus the sale and use must be based on proper
analysis to ensure food safety (Bates, 2010). Feed microscopy is a technique to assure
the quality of ingredients. The technique determines if an ingredient meal is derived
purely from a single source, fish for example, or if the meal is a mixture of various
ingredients and in what proportions (Bates, 2010).
According to the same author, other feed quality problems include rancidity, aflatoxin
contamination and nutrient loss. Further, rancidity in feeds is the perioxidation of lipids
in unsaturated form (Cruz, 1994). Fish meal, shrimp head meal, copra meal, rice bran
and marine oils are ingredients all prone to rancidity (Chow, 1980). Rancid lipids make
feed unattractable, less palatable, reduce nutritional value and produce toxic by-
products. High temperatures is one of the most improtant factors promoting rancidity
(Chow, 1980). Alfatoxin contamination is the most toxic natural contaminats in artificial
diets. The presence of molds in feeds suggest alfatoxin contamination; moreover, high
temperature and humidity favour growth of molds (Cruz, 1994).
12
Vitamin loss in feeds is caused by heat, moisture, light, high pH, presence of certain
minerals, lipid oxidation and transport under tropical conditions (Cruz, 1994). In
addition, leaching of water soluble vitamins in shrimp/prawn diets is a common
problem. Thus, to compensate for these losses, feeds are usually prepared with vitamins
and feed binders.
The safety of feed is important, and there have been reports of risks associated with the
use of contaminated aquaculture feeds either from feed ingredients used or from
contamination due to prolonged or improper storage (Tacon, 2010). Major potential feed
contaminants are: salmonellae, mycotoxins, veterinary drug residues, persistent organic
pollutants, agriculture and other chemicals, heavy metals (e.g., Cd, Pb, Ag) and excess
mineral salts (e.g., As, Se, F, Cr) (Tacon, 2010). In addition there is also the risk of these
contaminants passing along the food chain through contaminated aquaculture products
to the consumers.
1.7 Feeding trials in Fiji
In Fiji, the use of rice bran, mill mix and coconut mill in commercial stock feeds for
tilapia and prawn culture began in the early 1980’s (Gonzalez and Allan, 2007). In 1984,
research on aqua feed formulation and feeding trials began at Naduruloulou Research
Station (NRS). Following this research, a tilapia commercial pellet was produced in
1998 and is now produced and sold by Crest Feed Mill Ltd. Currently; this commercial
tilapia pellet is being used by some semi-commercial and commercial tilapia and prawns
farmers (Gonzalez and Allan, 2007).
All feed mills in Fiji are owned by the private sector with the exception of NRS feed
making plant which is used for experimental diets (Gonzalez and Allan, 2007). Crest
Feed Mill Ltd. is the largest feed producer and purchases most of its feed ingredients
such as fish meal, soybean mill, vitamin premix and mineral premix from New Zealand.
Flour Mill of Fiji Ltd produces mill mix and its subsidiary companies produce coconut
oil and coconut meal. A local producer of fishmeal is Pacific Fishing Company Limited
in Levuka, but its quality is very variable. Meat and bone meal is produced by Fiji Meat
13
Limited in Nasinu and rice by products such as broken whole grains, rice bran and rice
pollard can be obtained from numerous rice mills.
Farm–made aqua feeds for tilapia and prawn culture is rare but various combinations of
local ingredients have been used by successful farmers. In addition to purchasing the
current tilapia pellet from Crest Feed Mill, farmers prefer using a mash consisting of 40
percent coconut meal, 35 percent mill mix and 25 percent meat and bone meal which
was formulated at NRS in 1988 (Gonzalez and Allan, 2007).
Despite information available on the nutritional requirements of prawns, farmers do not
have access to this information nor knowledge on how to utilize such information. In
addition, the suitability of local ingredients available to farmers in Fiji, appropriate
inclusion levels in diets, methods of processing and economics of using such ingredients
is poorly understood. Since the cost of commercial tilapia or prawn pellet is too high
(FJ$ 1.52/kg), farmers are limited in the choice of alternatives since recommendations
on the use of locally available material is not available to the farmers.
1.8 Research objectives
General
To develop experimental feed formulations for freshwater prawns based on local low
cost feed ingredients
Specific Objectives:
1) To identify local ingredients with potential use in freshwater prawn feeds based on
availability, composition and cost.
2) To assess the utilisation of local feedstuff candidates.
3) To formulate experimental diets incorporating local ingredients
4) To conduct M. rosenbergii growth trial in ponds comparing the two experimental
diets against two local commercially-available feeds.
14
1.9 Thesis Overview
This thesis is organized into five chapters as outlined below:
Chapter 1 contains an introduction to the global production of giant freshwater prawn
M. rosenbergii. Additionally, this chapter presents a brief history of the development of
aquaculture and the introduction of M. rosenbergii in Fiji. As well as background
information of previous feeding studies carried out in Fiji, and the research objectives.
Chapter 2 includes a detailed literature review on dietary requirements of M.
rosenbergii, assessment of feed ingredients, feed ingredient analysis, feed formulation
and development, grow out feeds both farm- made feeds and commercial feeds and
water parameters.
Chapter 3 describes the materials and methodology that was followed for the assessment
of ingredients, comparison of two experimental formulations against two commercial
feeds, diet formulations, and analysis of data.
Chapter 4 presents the results and discussions of the results of growth performance,
survival rate and feed intake of freshwater prawns in two indoor experiments and grow-
out pond experiment.
The final section contains a general conclusion, which summarizes the total findings
from the research project as well as recommendations for future research. All the
additional tables and figures could be found in the Annex section.
15
2.0 LITERATURE REVIEW
2.1 Dietary requirements of M. rosenbergii
Nutrition studies for shrimp were initiated in the early 1970’s (Lim, 1996). Different
studies are based on differences in research methods, variation in species, size,
source, shrimp state, environmental conditions, experimental design and diet form,
composition and processing. Nutrition data for some species such as trout, salmon,
channel catfish and common carp are well established and efficient feeds have been
developed (Lim, 1996).
During the last decade, the knowledge of the nutritional requirement of M.
rosenbergii has increased dramatically. Some results indicate that this species and
species of penaeid shrimps have many requirements in common (D’Abramo, 1998).
Other results suggest that M. rosenbergii has unique dietary requirements that are
probably characteristic of its freshwater habitat and feeding habits. Most of the
information derived from classical nutrient requirement research has yet to be
applied to the development of practical commercial diets for pond grow-out culture
(New et. al., 2010).
Since freshwater prawns are omnivores, they can utilize a wide variety of locally
available feedstuff including commercial by- products as ingredients in formulated
feeds (Table 2). Protein sources such as mussel meat meal, squid meal, shrimp meal,
fish meal and earthworm meal support better growth, molting frequency and survival
in freshwater prawn as compared to plant protein sources such as oil seed cakes
(Leena et. al., 1997). Non–conventional ingredients such as leaf meals and single-
cell proteins such as Spirulina sp usually used as supplementary diets of post larvae
of freshwater prawn (James et. al., 1992). Freshwater prawn fed a 40 percent protein
diet with energy level of 400 kcal/100g attained higher fecundity over prawns fed 30
percent protein and 442 kcal/100g diet (Das et. al., 1996).
A study by Hari and Kurup (2003b) indicated an optimum protein level of 30
percent. In another study by Mitra et. al. (2005) found that diets with about 35-40
percent protein and gross energy level of about 3.2 kcal/g diet and protein energy
ratio of about 125-130 mg protein/kcal are suitable for growth of this species in clear
water systems that do not have natural food supply. Using different protein sources
16
in various combinations rather than singles source to substitute fishmeal is more
effective and reduces risk of high levels of single anti-nutrient in the diet (Hossain
and Jauncey, 1990).
Table 2. Nutrient requirements of the giant freshwater prawn M. rosenbergii
Nutrients Growth stages Requirements Protein (%) Brood stock 38-40 Juveniles (2nd 4th month) 35-37 Adult (5th 6th month) 28-30 Carbohydrates (%) For all stages 25-35 Lipid including phospholipids (%)
For all stages 3-7
HUFAs (%) >0.08 Cholesterol (%) For all stages 0.5-0.6 Vitamin C (mg/kg) Grow out 100 Calcium / phosphorous 1.5-2.0 : 1 Zinc (mg/kg) 90 Other materials Not yet known Energy Brood stock 3.7-4.0 kcal/g feed Other stages 2.9-3.2 kcal/g feed (Source: Mitra et. al., 2005).
On the other hand, plant proteins have been found to be relatively poorly-utilized in
crustaceans in terms of growth in comparison to protein of animal origin. However,
digestibility studies in freshwater prawn have indicated that the species can
efficiently digest both plant and animal protein sources (Ashmore et. al., 1985). The
omnivore nature of freshwater prawn permits the use of a wide variety of locally
available feedstuffs including commercial by-products as ingredients in formulated
diets.
There is also mounting evidence that low cost plant proteins are well utilized in
artificial diets formulation for this species (Sarma and Sahu, 2002; Hari and Kurup,
2003b). Tidwell et. al. (1993) have proven that soybean meal is a high quality protein
source well digested by M. rosenbergii. Efficient utilization of dietary ingredients is
dependent on the protein/energy ratio. Summerlin (1988) found that for M.
rosenbergii, the Protein: Energy (P: E) ratio between 127 to 143 mg protein/kcal
yielded the highest weights. In addition, three different diets containing protein levels
30, 35 and 40 percent in combination with two lipid levels 10 and 14 percent showed
narrow P: E ratio of 17 mg crude protein/kcal produced significantly higher growth
rate, survival and significantly lower feed conversion ratio for the species (Goda,
2008).
17
Studies to investigating soybean meal as substitute for fish meal have shown
promising results (Koshio et. al., 1992; Tidwell et al., 1993; Du et. al., 2003; Goda,
2008; Hasanuzzaman et. al., 2009). The effect of dietary rice bran levels on the
growth and maturation of M. rosenbergii has been investigated by Hari et. al. (2003),
and they determined that diets should contain from 300 to 350 g/kg feed of rice bran
to ensure good growth and survival, while no conclusive results can be drawn on its
effects on maturation. Potential terrestrial animal ingredient such as meat and bone
meal were studied by Hossain and Islam (2007) at 14 percent meat bone meal
inclusion showed no significant differences in growth performance of M. rosenbergii
while Yang et. al., (2004) reported no effect on growth for M. nipponense and L.
vannamei respectively fed diets where fish meal was replaced by meat bone meal.
Similarly, in Bangladesh low cost diets were formulated at 20 percent fish meal, 10
percent meat and bone meal, 15 percent mustard oilcake, 15 percent sesame meal, 35
percent rice bran, 4 percent molasses and 1 percent vitamin–mineral premixes and
recommended for monoculture of M. rosenbergii in ponds (Hossain and Paul, 2007).
Dietary lipids also give palatability to feed and aid absorption of fat soluble vitamins
and sterols. The required amount of dietary lipid for freshwater prawn is based upon
satisfaction of the requirements for essential fatty acids and its supply as a good
source of energy to reduce dietary protein requirements (New et. al., 2010). The
dietary lipid level in prawns can range from 5 -10 percent given the lipid source
contains enough levels of essential fatty acids (Mitra et. al., 2005).
Carbohydrates are considered the least expensive form of dietary energy for animals.
Cereal grains are the usual sources of carbohydrates in most of the aqua feeds and
these cannot be economically supplemented with other sources. The major
carbohydrates of feed ingredients for aquatic animals are oligo- and polysaccharides
(starch, cellulose) (New et. al., 2010). Cellulose may actually serve as a source of
energy (Briggs, 1991) rather than being nutritionally inert as once assumed. The
nutritional value for dietary fibre for M.rosenbergii may reside in an increase in
metabolic efficiency that is reflected in higher growth rates. Gonzalez -Pena et. al.
(2002) fed diets that contained 0, 5, 10 and 15% α – cellulose to large (37 g) and
small (13.5 g) M. rosenbergii. The mean rate gastric evacuation increased
significantly at 10 and 15% levels for the large prawns. Weight gain, FCR and
18
protein efficiency also significantly improved. Significant improvement in growth,
FCR and protein efficiency ratio only occurred at 10% level for smaller prawns.
Dietary crude fiber at 5 percent level may stimulate microbial gut flora, in
recommended level in commercial diets (Paulraj, 1995). In contrast, in laboratory
experiments, the growth of M. rosenbergii was unaffected at 30 percent dietary fiber
(Fair et. al., 1980). The total amount of dietary carbohydrate that can be utilized by
freshwater prawn depends on the digestive capability. The high production of
amylases found in M. rosenbergii is attributed to its omnivorous feeding habit. Corn
starch and dextrin are good sources of dietary energy (Querijero et. al., 1997c). Soya
bean meal is one alternative mostly studied to replace fish meal in marine fish and
crustaceans. These have been reported by Tacon and Akiyama (1997); Davis and
Arnold (2000); Webster and Lim (2002).
Vitamin requirements of freshwater prawns are probably similar to those determined
for other aquatic species because vitamin serves as a metabolic catalyst for the same
chemical reactions (New et. al., 2010). The only reported quantitative vitamin C
requirement is by D’Abramo et. al., (1994) using 100 mg/kg ascorbylpalmynate. In
an experiment, semi purified diets using ascorbyl-2-polyphsphate to determine
vitamin C levels at 135 mg/kg showed good response for M. rosenbergii juveniles
(Hari and Kurup, 2003a). Various types and levels of vitamin/mineral premixes have
been used in prawn studies.
The knowledge of the quantitative requirement of minerals for M. rosenbergii is
lacking, particularly to satisfy the calcium and phosphorus requirement for growth
for the freshwater phase is essential (New et. al., 2010). There is a relationship
between dietary calcium level and water hardness. In an experiment with 1.5:1 ratio
of calcium to phosphorous of dietary level 3 and 2 percent calcium and 23, 51 and 74
mg/L of calcium carbonate (CaCO3), best survival and weight gain was obtained for
dietary level 3 percent calcium and water concentration of 51 mg/L CaCO3 in water
whereas 2 percent calcium diet performed best at highest alkalinity level of 74 mg/L
CaCO3 (Zimmermann et. al., 1994).
Feed stimulation must be considered in formulating diets to be acceptable to aquatic
animals. The use of antioxidants as feed additives in feeds and feedstuffs prevent
losses of nutrients and increases the shelf life. (Santiago et. al., 1994). Mostly,
19
substances which have unsaturated carbon atoms (double bonds) in the molecular
structure are susceptible to autoxidation (Santiago et. al., 1994). Ingredients usually
affected are fats, oils, vitamins and pigments. Rancidity causes palatability problems
in feeds, loss in vitamin strength and color effectiveness in pigments (De Silva,
1989).
2.2 Assessment of Feed Ingredients
The evaluation of feed ingredients is important to nutritional research and feed
development for any aquaculture species. In evaluating ingredients for use in
aquaculture feeds, there are several important knowledge components to be
understood to enable judicious use of particular ingredients in fed formulation
(Glencross et. al, 2007). This includes information on ingredient digestibility,
ingredient palatability and nutrient utilization and interference. The choice of
ingredients also depends on various factors such as availability, cost, gross chemical
and digestible composition, physical properties and market demands (De Silva,
1989). Provided a diet is formulated on a digestible nutrient and energy basis, and it
satisfies the animal’s nutrient and energy requirements, most variability in
performance is then usually attributable to vagaries in feed intake.
Ingredient digestibility is the measurement of the proportion of energy and nutrients,
which an animal can obtain from a particular ingredient through its digestive and
absorptive processes (Glencross et. al, 2007). Several methods have been used to
determine diet and ingredient digestibility in aquaculture species. Many factors may
affect measurement of digestibility, but the most crucial is the leaching of nutrients
from the feed and faecal matter into the water (Glencross et. al., 2007). However,
this method to determine digestibility have not gained much popularity in
aquaculture due to the difficulty in approximating faecal output as total faecal
collection is hard to attain. Total collection has been attempted by several researchers
in many studies involving fish but results have not proven sufficient (Choubert et.
al., 1979; Vens-Cappell, 1985). Thus, faecal output can be estimated by the dilution
in faeces of an indigestible marker consumed by the fish in an exactly known
quantity. Digestibility studies in freshwater prawn have indicated that the species can
efficiently digest both plant and animal protein sources (Ashmore et. al., 1985). In
crustaceans, leaching is minimized by using a good feed binder, feed attractant, and
by frequent collection of the faeces. While chromic oxide (Cr2O3) is perhaps the
20
most commonly used marker, rare earth metal oxides such as ytterbium oxide,
yttrium oxide and other are earth metals are gaining favor (Austreng 1978; Ringo
1995; Austreng et. al. 2000). For studies focusing on lipid utilization, hydrocarbon
markers such as cholestane have proven useful (Carter et. al., 2003).
Ingredient palatability is the combination of both attractiveness and ingestion of a
diet (Glencross et. al, 2007). While it may be difficult to ascertain whether or not a
fish ‘likes’ some flavor or not, it is certainly possible to determine differences in
amounts of feed eaten (Glencross et. al., 2007). Irrespective of how digestible and
available the nutrients and energy from an ingredient might be, if the ingredient
reduces feed intake, then it will have limited value. Feed preference studies are one
way of assessing effects on intake. The use of self-feeding through computer-
managed response mechanisms is another option that has been frequently used to
allow discrimination of feeds by fish and certainly assist in removing human error
from feed intake assessment process (Juell 1991; Boujard and Le Gouvello 1997;
Burel et. al. 1997).
The determination of nutrient utilization or interference with nutrient utilization
because of incorporation of any one ingredient is a complex step in ingredient
evaluation. The complexity is largely due to issues associated with metabolic
modifiers such as glucosinolates and effects of differences in amino acid composition
and availability (Glencross et. al, 2007). With most nutrient utilization studies, the
response variable is growth. This is often simply defined as the difference between
initial and final live weights (weight gain). For an assessment to be made on the
nutrient utilization of a diet, and by reference an ingredient, there is a need to
measure feed intake (Glencross et. al, 2007). The efficiency by which nutrients and
energy are retained from feeds provides a useful assessment of the efficiency of
nutrient utilization from diets (Cho and Kaushik 1990; Booth and Allan 2003;
Glencross et. al. 2004).
Effects of dietary treatments on whole somatic or organ-specific composition are
another means of assessment of potential ingredient effects (Ruyter et. al. 2000;
Booth and Allan 2003). Evaluations of immune responses and parameters associated
with an immune challenge have also been effectively used in recent times (Hardy
1999; Krogdhal et. al., 2000; Montero et. al., 2003).
21
Utilization can be measured in several ways. One of the most obvious ways is to
assess the weight gain achieved when fish are fed certain diets. In this regard,
animals are fed a particular diet for a certain period of time and their weight gain
measured between two time points after being fed on a diet. According to results
obtained, comparisons can be made among treatments and conclusions drawn
(Glencross et. al., 2007). Further detail can be added to this style of assessment by
examining the changes in composition of the animal, for example protein and/or
energy (or indeed any nutrient) as a function of the intake of protein or energy (Cho
and Kaushik, 1990). This is referred to as the protein or energy retention efficiency.
In order to define the maximum inclusion levels of the ingredients in the
experimental diets, before negative effects are observed, we will conduct feed intake
trials using diets with incremental inclusion of the tested ingredients.
Ingredient inclusion trials are probably the simplest way to examine effects on feed
intake. An ingredient can be included in a reference diet to create a test diet and then
the reference and test diets are fed to apparent satiety to replicate groups of animals
for each diet (Glencross et. al., 2007). Significant differences in feed intake between
the reference and test diets reflect the apparent palatability because of the test
ingredient. The issue of how much ingredient to include in the test diets is somewhat
subjective. Ideally, a range of test ingredient inclusion levels that cover what would
be the practical inclusion levels should be used, as this also allows examination of
critical palatability levels or break points (Sheer, 2000). The final assessment of feed
intake effects can be examined either on a pair-wise time-series basis or simply as a
comparison of differences in absolute intake over a period of time (Glencross et. al.,
2007).
An ingredient can be incorporated in a reference diet to create a test diet whereby
both diets are fed to the animals. Significant differences in feed intake between the
reference diet and test diets indicate the clear palatability of the test ingredients
(Glencross et. al., 2007). However, palatability assessments for aquatic animals to
demonstrate feed intake responses are not essentially easy. For an animal to
demonstrate a feed intake response, it must be given the opportunity to refuse feed,
therefore feeding beyond apparent satiety is imperative. Regardless of whether an
ingredient affects attractiveness in palatability, its effects on feed intake must be
22
assured independently of effects on utilization of energy and nutrients. Feed
preference studies are one way of assessing effects on intake (Glencross et.al., 2007).
In 2004-2005 a mini-project funded by Australian Centre for International
Agriculture Research (ACIAR) with Secretariat of the Pacific Community (SPC)
partnership, Fiji Fisheries Department and Papua New Guinea (PNG) conducted a
survey of potential feed ingredients for both countries. A few simple feeds were
formulated of which some were tested with tilapia in Fiji (Gonzalez and Allan,
2007). These ingredients included rice, broken rice, rice bran, rice husk, mill mix,
pea mills, local fish meal and fish oil, meat mill, tallow, chicken manure and copra
meal. However, the digestibility determination of these ingredients, simple
measurements of protein/energy requirements and formulation and trials of new
formulations for prawns was not undertaken.
In Fiji, the grow-out of freshwater prawn from PL to adult stage uses commercial
tilapia pellet or agricultural by-products such as mill mix and copra without the
provision of specific formulated feeds. In NRS, the commercial feeds for freshwater
prawns and tilapia are supplied by Goodman Fielders International (Fiji) Ltd. Crest
Feed Mill which produces 2 tons (80 x 25 kg bags) of both feeds per week (R.
Daulako, pers. Comm., 2010). Due to the high demand for other poultry feeds, the
Crest Ltd had ceased the production of prawn and tilapia pellets at the beginning of
2010. Ninety five per cent of the ingredients used in producing stock feed are
imported from overseas (i.e., meat and bone meal from New Zealand, soybean meal,
offal and wheat from United States of America).
Increasing costs have resulted in the increase in price of feed. Currently, a 25 kg bag
of prawn and tilapia feed sold at Crest Feed Mill cost FJ$ 40.20 and 31.32
respectively. Pacific Feeds Ltd is also a producer of tilapia and prawn pellets costing
FJ$ 25.00 and 37.00 respectively (R. Daulako, pers. comm., 2010). As part of the Fiji
Islands Freshwater Aquaculture Sector Plan 2005-2010, the Government has
recognized the potential that freshwater prawn farming can have in Fiji, and thus
emphasized the development to improve and expand production in the coming years.
23
2.3 Feed Ingredient Analysis
The chemical composition of feed ingredients is usually defined by the standard
proximate composition methods published by the Association of Analytical
Communities International (AOAC, 2005) following the analysis of diets and
feedstuff by the Weende System. This analysis is only a crude estimate of the major
classes of nutrients present and should be used as a general guide to assessing
potential ingredients for a diet. The materials are divided into six portions which
undergo various chemical tests determining moisture, crude protein, crude fiber,
crude fat (ether extract), mineral matter (ash) and nitrogen–free extract (FAO,
2009a).
Table 3. Reported proximate analysis for selected ingredients used in compound aqua feeds. Values
expressed as % as- fed basis.
Moisture Crude protein Lipid Crude fibre Ash
Fishmeal (Tuna) 8.2 62.2 7.4 0.8 19.4
Meat Bone meal
(rendered)
7.5 50.1 10.6 2.4 28.8
Wheat (germ meal) 9.7 26.6 7.3 3.3 4.7
Copra meal 4.0 7.2 64.6 3.8 1.9
Pea meal 11.3 23.1 1.5 6.2 3.2
Values extracted from FAO, 2009a.
The feed value of meals derived from fishery or terrestrial by-products depends on
numerous factors including (1) origin and source of the fish or crustacean species
processed; (2) the freshness and condition of the raw material prior to processing; (3)
the cooking and /or drying process used for the manufacture of the meal (time and
temperature); (4) the grinding and storage of the processed meal prior to usage and
(5) the biological availability of the nutrients present within the finished processed
meal (FAO, 2009a).
In general fishery products are good sources of essential dietary nutrients for most
farmed finfish and crustaceans with the nutrient profile of whole processed meals
approximately close to the known dietary nutrient requirement of the species. In
common with fishery by-products, terrestrial livestock products are also rich sources
of cholesterol, vitamins and minerals. In general, the major carbohydrate usually
present in cereal by-products is in the form of starch granules with linoleic and oleic
24
acid. Compared with the cereal grain, the oilseeds and their oil extraction products
are rich sources of protein (20-50 % by weight: Medale and Kaushik, 2009) and
relatively poor sources of digestible carbohydrate. Grain legumes are good sources of
protein energy and several B vitamins.
2.4 Feed Formulation and Development
Diet formulation means to interpret nutrients and energy requirements into a
balanced mixture of ingredients for certain animals (De Silva, 1989). Nutritionally
complete feeds are used whenever natural foods are absent or only contribute in
small quantity to nutrition.
Firstly, a reliable updated database on the chemical, physical characteristics and the
local availability of the nutrients and ingredients is needed (Kaushik, 2000). The
formulation will depend on the cost and availability of the raw materials. There are
various methods to formulate a diet. Linear programming is used with different
levels of complexity and is based on mean ingredient data. A number of commercial
software is available for feed formulation, for example WinFeed, Feedmania and
Agridata (Kaushik, 2000). The computerized least cost formulation approach has
been used within the commercial aquaculture sector. There are many factors to
consider when formulating a good diet (Cho et. al., 1985). These include:
1. Age and species being cultured.
2. Acceptability to the animal - the feed must be palatable enough to encourage feed
intake.
3. Digestibility - the nutrients in the feed must be easily digestible to be utilized by
the animal.
4. Cost – several combinations of feed ingredients can be made to meet the nutrient
requirement of the animal. However, the least cost formulation meeting this
requirement is desired.
5. The presence of anti-nutritional factors - when present in the feeds and given in
excess amounts to the animal can have harmful effects.
In addition, the type of feed required, processing methods, and type of culture
system, all of these factors influence formulation.
25
The basic process of feed making is the diets are often made with purified
ingredients that are blended with water, pelleted through a selected die, dried and
kept frozen or crumbled before use. Currently, extrusion technology has become
more common in aquaculture feed industry. Extrusion, improves water stability,
improves the digestibility of starch and decreases levels of anti-nutritional factors
and bacterial counts in the finished feeds (De Silva, 1989).
2.5 Grow out feeds
While feed represents the largest operating cost item, attention on development of
research and farming strategies seeking to reduce feed costs by improving on farm
feed management techniques must be emphasized (Tacon, 2010). The preparation of
farm-made feeds in semi-intensive farming system by farmers using locally available
products is less expensive for farmers than commercial feeds.
Formulated aquaculture feeds are often high in protein and fat and the bulk of those
generally provided by fish meal and fish oil. Due to the high cost and foreseeable
long term supply problems, progressive increase in the use of economical protein and
lipid sources in aquaculture feeds is inevitable. Feed manufacturers therefore, require
information on the nutritive value of various economical protein and lipid sources.
Crustacean researchers have been able to reduce feed cost by substituting low cost
protein with no loss in growth and feed efficiency. However, almost all of the
commercially available aqua feeds produced for small intensive farming system is
usually over formulated. Inadequate knowledge by small scale and medium scale
entrepreneurs is the main constraint when it comes to farm made feeds (FAO,
2009c). Knowledge on the acceptable inclusion levels of ingredients is known but
farm economics knowledge is scarce. In addition, the sharing of information on the
seasonality and availability of ingredients is lacking (Tacon, 1995). With the increase
in feed and farm production costs, coupled with increasing degradation to the
environment and often static/decreasing market value of many farmed species,
attention on development of research and farming strategies seeking to reduce
feed/fertilizer costs by improving on farm feed management techniques must be
emphasized (Tacon, 1995).
26
According to Tacon (2010), if aquaculture is to continue its role in food security in
developing countries, production of herbivorous or omnivorous finfish/crustacean
species should be targeted for production in semi-intensive low cost systems rather
than high value carnivorous species cultured in intensive system requiring
nutritionally complete high cost diet. Furthermore, feed survey studies reveal that
many aquaculture producing countries are still highly dependent on imports for
providing feed ingredients. The availability and usage of feed ingredients in these
countries favors energy-rich rather than protein-rich ingredient sources with most
local ingredients being used for domestic consumption and farm made aqua feeds.
Ingredients selected should be based on the sustainability, nutrient density and
nutrient digestibility (Tacon, 2010).
In semi-intensive pond –based culture, the productivity of the pond can contribute to
satisfying the nutrient requirements. However, as biomass of freshwater prawns in a
pond increase, normal levels of secondary productivity cannot sustain the nutritional
needs for maximum growth, therefore supplementary feed resources are needed. To
balance the nutritional deficiencies, farm- made or commercially manufactured diets
are used. These diets serve as either direct supplemental source of nutrients or as
indirect source by improving the natural productivity of the pond.
Freshwater prawn production in ponds depends on the ability of the environment to
produce natural food. Natural productivity in ponds depends on various factors such
as water temperature, soil and water fertility, and intensity of solar radiation affect
(Moriarity, 1997). Fertilization of ponds can be achieved with inorganic fertilizers, or
locally available organic fertilizers such as compost made with plant and animal
wastes, animal manure, or plant material. The overall nutritional budget of pond
culture will be highest at low stocking density and at the start of the pond production
cycle when total animal biomass or standing crop is lowest (Tidwell et. al., 1997).
While prawns can receive considerable nutritional gain from natural foods at
relatively low biomass densities (< 1,000 kg/ha) (Tidwell et. al., 1997), at higher
stocking densities individuals may be more dependent on prepared diets (Tidwell et.
al., 1999). The prawns are fed with farm made or commercial feeds to improve
production level. Feeding and management are great considerations in a successful
prawn culture. Fish meal contributes majorly to the formulated feed as a protein
27
source. Due to the scarcity and increasing prices of fish meal, alternative sources of
protein have been investigated.
In addition, maximum performances can be achieved through supplementary feeding.
In Fiji, majority of local farmers use Crest Tilapia feed as prawn feed thus is used as
a comparison in this study. Reducing costs may be achieved by increasing stocking
densities in ponds and raceways. To obtain maximum growth feeds must contain
proper balance of energy, protein, vitamins and minerals while preserving cost
efficiencies. Hence, it is important that the knowledge of nutrient requirements, feed
preparation from local ingredients, feeding strategies and cost effectiveness of
prepared feeds is understood in achieving commercial success.
2.5.1 Farm- made feeds
Farm-made feeds is defined as ‘feeds in pellet or other form, consisting of one or
more artificial and/or natural feedstuff producing the exclusive use of a particular
farming activity, not for commercial sale or profit (New et. al., 1993). Small scale
farmers mainly in Asia use farm made aqua feeds. New and Csavas (1993) noted that
10 percent of fish production in Asia use commercial feeds, the other 90 percent use
farm made feeds.
Farm-made feeds consist of trash fish, soy bean meal, corn meal, vitamin and
minerals, piglet and chicken feed (New, 2002). The process of making farm-made
feeds for prawns have been described by various authors such as New and Singholka
(1985); New (1987); New et. al., (1993); and New (2002). Work on farm-made feeds
for M. rosenbergii remains thin because it is difficult and expensive to measure the
composition of local ingredients. However, Kunda et. al. (2008) stated that due to
scarcity and high cost of commercial feed, the development of freshwater prawn feed
made from local ingredients was popular in Bangladesh. In Fiji, some established
farmers prepare on farm feed of a diet containing 50 percent fish meal and 50 percent
rice bran or broken rice during the first two months and a diet containg 25 percent
fish meal or meat bone meal, 40 percent copra mill and 35 percent mill mix which a
tilapia feed combination for the third through to the fifth month of grow out (J.
Vasuca pers.comm, 2010).
28
However, statistical information on the size and extent of this sector is unreliable and
little or no guidance is usually given to help these farmers formulate and mange their
feeds (De Silva, 1989). Government agencies and feed manufacturers have driven
this sector away from the use of farm- made feeds to the purchase of commercial
aqua feeds.
2.5.2 Commercial feeds
Commercial giant freshwater prawn feeds have been reported to contain protein
levels ranging from 24 to 39 percent in Hawaii (Corbin et. al., 1983), 28-36 percent
in Taiwan (Hsieh et. al., 1989) and 22-30 percent in Thailand (New, 1990). A wide
range of commercial feeds are available with varying levels of nutrients and
ingredients.
Commercially manufactured feeds have been used in experimental ponds and FCRs
usually range from 2.5: 1 to 3.5:1 (New et. al., 1993). Hossain et. al. (2000) reported
FCR value of 3.1-4.9 for prawns. Similarly, William et al. (1995) reported FCR
value of 2.2-2.4 and Sarma and Sahu (2002) recorded an FCR of 2.4 with a diet
containing 37 percent protein for freshwater prawn M. rosenbergii. For semi-
intensive culture, FCR values of 2.5-3.5 are considered good (Hossain et. al., 2000).
In intensive systems higher FCR such as 3.0–3.5 are accepted as there is limited
natural food in the pond. If growth is slow and FCR is low, it indicated that more
food is needed to speed up growth. If FCR value is very high, it means that not all
feed in being eaten thus it is being wasted.
Since freshwater prawns are omnivorous, this provides an excellent opportunity of
using locally available feedstuffs. However, due to the low amounts available and
unreliability of supply of these feedstuffs, large feed manufacturing companies are
not interested in using them as ingredients in commercial feed manufacturing (New
et. al., 2010).
2.6 Water Parameters
Much variation in growth performance of prawn is noticed under different
management practices. Most important is the management of suitable water quality
variables and proper feeding practices. Dissolved oxygen is particularly important
and a good oxygen monitoring program is necessary because prawns live on the
29
bottom levels thus should be monitored within the bottom of water. A high pH can
cause mortality either directly by means of creating a pH imbalance relative to the
prawn tissue or indirectly by causing a larger proportion of ammonia to exist in the
toxic unionized form (Costa-Pieroe et. al., 1984). Water temperature is probably
most important in prawn culture as it directly affects metabolism, oxygen
consumption, growth, molting and survival (Soundarapandian et. al., 2008).
30
3.0 MATERIALS AND METHODS
3.1 Experiments in aquarium- Assessment of ingredient inclusion levels
3.1.1 Experimental set up
The experimental system was conducted at the Sea Water Wet Laboratory of the
University of the South Pacific (USP) between September and December, 2010.
Eighteen 100 L aquaria (58.5 x 38.5 x 44.5 cm) were connected to a temperature
controlled recirculation system. All aquaria were kept on a wooden bench to assist
better observation and accessibility. Water was supplied from a 300 L sump tank
with a constant water flow rate (0.3 L/min) into each aquarium. Water was
circulated through a common biological filter system. The water parameters were
checked daily with to maintain within limits as follows: temperature 29.0±0.5 ºC, pH
6.5 – 7.5, DO > 6.0 mg/L, ammonia <0.2 mg/L, nitrate <1.0 mg/L and nitrite <0.1
mg/L. A natural photoperiod of 12 h light and 12 h darkness was maintained through
the experimental period.
3.1.2 Local ingredients
The local ingredients available in Fiji with costs and sources are shown in Table 4.
The feed ingredients were purchased in 35 kg bags and stored in the freezer at the
Wet-lab. Feed stuff was analyzed at the QDPI laboratory in Brisbane, Australia. Not
all the ingredients were used in the formulations as it was not available in supply at
the time of experiment and obtaining these ingredients was not economical due to
shipment expenditure.
Table 4. Raw ingredients and suppliers in Fiji.
Price/Ton Ingredient Source FJD$ AUS$
Copra meal Rewa Dairy Fiji Ltd, Suva 580 480 Fish meal Pacific Fishing Company, Ltd, Suva 800 662 *Meat bone meal Fiji Meat Industry Board, Suva 760 629 *Meat fish meal Pacific Fishing Company, Ltd, Suva 800 662 Mill mix Flour Mills of Fiji, Suva 350 289 Pea meal Flour Mills of Fiji, Suva 550 455 Rice bran meal Evergreen Rice Ltd, Navua 560 463 Wheat Flour Mills of Fiji Ltd, Suva 825 682
* Meat bone meal and meat fish meal ingredients have no fixed proportions of its combination.
31
The ingredient inclusion levels were assessed in two separate experiments using diets
with incremental inclusions of the tested ingredients. Experiment 1 tested fish meal,
meat fish meal and meat bone meal. Experiment 2 tested mill mix, copra meal, wheat
and pea meal.
3.1.3 Formulation and feed preparation
Six experimental diets were formulated to be isoenergetic, isoproteic and isolipidic.
Diets for both experiments were prepared at the Physicochemical Laboratory
facilities at the School of Marine Studies (USP). All dry ingredients (except the
Premix) were sieved on 1.0 & 0.5 mm diameter mesh dies to remove any irregular
sizes of impurities such as small pieces of scales, hairs, grains, husk and large
fragments before weighing out the quantities required. The dry ingredients were
weighed out as per formulae (Tables 5 and 6), mixed manually and fish oil added
until a homogeneous mixture was obtained.
Table 5. Formulation (%) of the diets based on different inclusion levels (fish meal, meat bone meal and meat fish meal) tested on M. rosenbergii juveniles (Experiment 1).
Ingredients Control MBM1 MBM2 MBM3 MFM1 MFM2 Fish meal 41.2 16.5 8.2 0.0 8.2 0.0 Wheat 53.8 55.6 56.2 56.8 58.2 59.3 Premixa 2.0 2.0 2.0 2.0 2.0 2.0 Meat-bone meal 0.0 24.7 33.0 41.2 0.0 0.0 Meat-fish meal 0.0 0.0 0.0 0.0 30.2 37.7 Fish oil 3.0 1.2 0.6 0.0 1.4 1.0 TOTAL 100 100 100 100 100 100
a Vitamin-mineral premix obtained from Port Stephens Fisheries Institute and supplied by Ridley Aquafeed Pty Ltd, Australia.
Water was added in quantity enough to get a wet consistency to obtain dough.
Following this, the mixture was then pressed through an electrical meat mincer of 2
mm diameter die pellets. The pellets were then dried in an electrical oven at 50 ºC for
24 h. The resulting pellets were then stored in labelled polyethylene plastic bags at -
10 ºC.
32
Table 6. Formulation (%) of the diets based on different inclusion levels (wheat, mill mix, copra meal, and pea meal) tested on M. rosenbergii juveniles (Experiment 2).
Ingredients WHT MM1 MM2 CP PM CTP Fish meal 44.0 44.0 35.0 30.0 40.0
Crest Tilapia pellet
Wheat 54.0 0.0 0.0 0.0 26.0 Mill mix 0.0 54.0 38.0 23.0 2.0 Copra meal 0.0 0.0 25.0 45.0 0.0 Pea meal 0.0 0.0 0.0 0.0 30.0 aPremix 2.0 2.0 2.0 2.0 2.0 TOTAL 100 100 100 100 100
a Vitamin-mineral premix obtained from Port Stephens Fisheries Institute and supplied by Ridley Aquafeed Pty Ltd, Australia.
Similarly, the above procedure was done for Experiment 2 diets preparation;
however fish oil was not used in the second experiment to keep lipid levels
homogenous. A few of the ingredients of Experiment 2 like pea meal and wheat had
to be finely grinded using an electric blender due to the coarse nature of the
ingredients. The commercial tilapia pellet of Experiment 2 was obtained from Crest
Feed Mill in pellet form and used as a reference diet because it is widely used by
Fijian farmers (Table 7).
Table 7. Formulation of Crest Tilapia Pellet (Experiment 2).
(Source: Crest Feed Mill, Nausori, Fiji).
Every ingredient and experimental diet was analyzed at the Queensland Department
of Primary Industry in Brisbane (Australia). The proximate composition of both
experiment of the ingredients and the formulated diets were analyzed according to
AOAC (2005) standards for moisture, ash, nitrogen, gross energy, fat, crude fiber,
and crude protein. Moisture was determined by the loss of weight sample dried to
constant weight no longer than 24 hr at 105 ºC. Ash was determined by taking the
ash portion of remains of burnt organic material in a muffle furnace above 550-600
Ingredients Quantity/Batch (kg) RPAN Fish Premix 8 Salt 4 Lysine 1 Choline 4 Wheat 310 Soya 218 Mill mix 490 Fish meal 320 Copra 240 Molasses 100 Pea meal 300 TOTAL 1995
33
ºC and calculated as percentage ash. The crude protein was calculated based on the
assumption that protein contains about 16 percent nitrogen by weight (6.25 x 16 =
100). Crude fat was determined by extracting ground samples continuously for a few
hours with ether. Nitrogen-free extract was determined on a dry weight basis by
subtracting the percentage of crude protein, lipids, fibre and ash from 100 %. Gross
energy content was determined by using a bomb calorimeter.
3.1.4 Stocking in aquaria
The 250 M. rosenbergii juveniles for Experiment 1 of were obtained from Dairy
Farm Fiji Ltd., located in Navua. Animals were acclimated for 10 d. Mean total body
weights and lengths were recorded with an initial weight of 3.45 ± 0.99 g using an
analytical balance (A&D®, model EK 600H) and a length of 50.27 ± 1.34 mm using
a electronic digital caliper (Lufkin®). The stocking density for Experiment 1 was of
10 juvenile prawns per each of 18 aquaria (3 replicates x 6 treatments-diets). The
stocking density for Experiment 2, was lower at 8 juvenile prawns per each of 18
aquaria (3 replicates x 6 treatments-diets, initial weight 6.85 ± 0.65 g and length
64.33 ± 1.15 mm) were obtained from NRS. Pieces of hollow PVC were placed in
each aquarium as prawns hide outs to reduce stress.
3.1.5 Feeding and Data collection
Prawns were fed ad libitum, twice a day (8:00 am and 4:00 pm) for a period of three
weeks in Experiment 1 and four weeks in Experiment 2. At each feeding, prawns
were given one hour to consume their feed ration after which uneaten feed was
removed by siphoning from each aquarium twice daily using a filtration apparatus to
collect the uneaten feed. Water replacement was made by pumping from a reserved
tank to fill up the loss due to evaporation and account for water loss during siphoning
of uneaten feed daily. This daily collection of uneaten feed was filtered onto a filter
paper which was then rolled into a foil and stored in the fridge until drying and re-
weighing the next day. The difference in weight was interpreted as feed consumed.
The water parameters temperature, dissolved oxygen (YSI® model 85) and pH
(YSI® model pH 100) were measured daily. After each experiment, the animals
were re-weighed and lengths measured. The ammonia, nitrate and nitrite were
measured using a freshwater quality test kit.
34
3.2 Experiment in grow out ponds- comparing two experimental formulations
against two commercial feeds
3.2.1 Experimental set up
Twelve rectangular earthen ponds of different size were selected and prepared for
stocking. Four treatments were assigned with three replicates per treatment diet
(Table 8).
Table 8. Pond dimensions and stocking density for the M. rosenbergii pond nutrition experiment conducted for 124 d. (ponds 1, 5, 9: Diet 1, ponds 2, 6, 10: Diet 2, ponds 3, 7, 11: CTP and ponds 4, 8,12: PPP)
Pond Pond area (m2) Stocking density Stocking number 1 113 7 791 2 116 7 812 3 105 7 735 4 105 7 735 5 121 7 847 6 100 7 700 7 126 9 1134 8 138 9 1242 9 138 9 1242 10 149 9 1341 11 140 7 980 12 157 7 1099
3.2.2 Formulation and feed preparation
Two experimental diets were formulated in this study. Diet 1 used premium local
ingredients (fish meal and wheat) of highest quality in the feed in order to achieve
the best growth performance regardless of cost while Diet 2 was formulated from
cheaper ingredients (meat bone meal, mill mix and copra) while meeting the basic
prawn nutritional requirements. The experimental diets were formulated to be iso-
nitrogenous (32 percent) CP and iso-energetic (19 MJ/Kg) on a dry matter basis. In
order to evaluate their relative performance, the two experimental formulations were
tested against two commercially available feeds (Crest Tilapia Feed and Pacific
Prawn Feed). Crest Feed Mill sells tilapia pellets at $31.32 per 25 kg bag and
freshwater prawn pellets at $40.20 per 25 kg bag. Pacific Feeds Limited sells the
same pellets at $25.00 and $37.00 respectively per 25 kg bag.
35
Table 9. Formulation (%) of experimental grow-out diets for M. rosenbergii pond grow-out trial for 124 d. (Experiment 3).
Ingredient Diet 1 Diet 2 CTP PPP FM 44.5 10.00
Crest Tilapia Pellet
Pacific Prawn Pellet
MBM 0.00 32.95 Mill mix 0.00 55.05 Copra meal 5.00 0.00 Pea meal 5.00 0.00 Wheat 43.50 0.00 Premix 2.00 2.00
The experimental diets were prepared by grinding some of the ingredients using a
crumbler to obtain fine powder. Ingredients were then weighed as per formulae using
a scale and placed in a mixer. While mixing, water was gradually added to obtain a
wet consistency forming dough. Once ingredients were thoroughly mixed, this was
screw pressed through a pelletizer using a 4 mm size pellet die. The two commercial
diets were crumbled, mixed with water and re-pelletized with the same size as the
experimental diets. Fifty kilograms of each diet was prepared using the same
process. The resulting pellets were dried for 4hours in a kerosene operated oven at 60
º C. Once dried, the pellets were placed in 25 kg bags and placed in an air-
conditioned room for storage. Samples of each diet were sent to QDPI laboratories
for analytical composition soon after manufacture.
3.2.3 Pond preparation and stocking
The experimental ponds were drained, overgrown grass removed; pests eradicated
eel nets placed at inlets and limed a week prior to filling with water. Each pond was
supplied with 2 aeration lines. The water turnover rate was about 5-10 % per day and
prawns were held under natural light (12 h light: 12 darkness) schedule.
According to a joint research associated with this ACIAR project, the GFP (Giant
freshwater prawn) Vietnam strain was identified as the best performing line thus was
used in this study. Once this strain had reached post larvae, 15,000 were transferred
from the hatchery to a quarantine facility for nursery culture in raceway tanks for
three weeks at NRS. Post larvae of freshwater prawn were kept in raceway tanks at a
density of 300 prawns/m2. The PLs were fed the commercial crest tilapia pellet.
The freshwater PL was counted and average initial weights and lengths of animals
taken. Animals of the same age of average initial body weight 0.083 g and average
36
length 19.03 mm were randomly selected and stocked into the experimental ponds at
stocking density of 7 and 9 PL/m2 of total area.
3.2.4 Feeding and data collection
Animals were initially fed 5 % body weight per day for the first month and this
decreased to 3 % body weight by the second through to fourth month. The daily feed
ration (DFR) was calculated using the formula provided by Jayachandran (2001):
DFR = stocking population x survival rate x average weight of prawn x % of feeding
rate. The daily ration of feed was divided equally and offered twice daily (9:00 am
and 4:00 pm). The feeds were dispersed by hand broadcasting over the water. No
fertilizer was used during the culture period. The growth performance indices during
the experimental period were conducted by netting out 100 animals per pond every
month and weighing individual animals using a Professional Scale® (GS-100.
accuracy of ±0.01g) electronic balance. The first sampling was done on the 28th of
April and 28 days consecutively for each month thereafter. Final harvest was
conducted on the fourth month after 124 d. The water level in each pond was reduced
to approximately 0.5m at the drain end. On the first day of harvest, each pond was
seined 2 times and then completely drained. The remaining prawns were then
manually harvested from the pond and placed in buckets of water and transported to
the hatchery for individual prawn weighing. The increase in length and weight were
used as measures of growth.
3.2.5 Water quality parameters
The water quality parameters such as temperature (°C), dissolved oxygen (mg/L) and
pH were monitored twice daily to ensure that water quality remained well within the
limits recommended for giant freshwater prawn. The temperature and dissolved
oxygen were measured using a Handy Polaris® (OxyGuard) meter and pH was
measured at 10cm below water surface using a YSI® pH meter (model pH 100).
3.2.6 Calculations
3.2.6.1 Growth performance, survival rate and feed intake
37
Weight gain (WG), total body length gain (BLG), specific growth rate (SGR; % per
day) feed conversion ratio (FCR), protein energy ratio (PER) and survival (%) were
all calculated as follows:
WG = Final body weight (g) – Initial body weight (g)
BLG = Final body length (g) - Initial body length (g)
SGR = (In FBW – In IBW) / t x 100; where FBW is final body weight; IBW is initial
body weight; In = natural logarithmic; t = time in days
FCR = Feed intake (g) / weight gain (g)
PER = live weight gain (g) / protein intake (g)
S (%) = (final number of prawns – initial number of prawns) x 100
Means and standard deviations were calculated and expressed as mean ± SD.
3.2.6.2 Production costs
The production costs were calculated as follows:
Initial Biomass = 0.08 g x initial number of prawns
Final Biomass = final weight (g) of prawns x final number of prawns
Product (g) = final biomass (g) – initial biomass (g)
Cost of feed (FJ$) = total feed (kg) x cost of diet (FJ$)
Cost of feed (AU$) = total feed (kg) x cost of diet (AU$)
Cost to produce 1kg prawn = FCR x cost of diet (FJ$)
3.2.7 Statistical analysis
The data obtained was statistically analyzed by performing analysis of variance
(ANOVA). The effect of different diets on FBW, WG, SGR, FCR, PER and S (%)
were carried out using to one way ANOVA assuming significant level (P ≤ 0.05).
Water parameters were also analyzed using one way ANOVA.
38
4.0 RESULTS AND DISCUSSIONS
4.1 Experiments in aquarium- Assessment of ingredients inclusion levels
4.1.1 Experiment 1
4.1.1.1 Proximate analysis
The proximate analyses of the experimental ingredients are shown in Tables 10. The
crude protein ranged from 13.91 to 57.69 % (dry weight) with meat fish meal
showing highest crude protein content and wheat showing the lowest. The crude fat
ranged from 4.40 to 26.50 % with meat fish meal showing highest crude fat content
and wheat showing the lowest. The gross energy ranged from 19.12 to 23.94 MJ/kg
with meat bone meal showing highest gross energy and wheat showing the lowest.
Table 10. Proximate composition of experimental ingredients (Winfeed Stochastic Formulation %
DM basis) (Experiment 1).
Components Fish meal Meat & Fish meal Meat Bone meal Wheat Dry matter 93.20 94.60 92.80 89.00 Protein 54.63 57.69 53.69 13.91 Lipid 20.50 26.10 26.50 4.40 Ash 24.50 17.30 16.90 5.40 Gross Energy (MJ/kg)
21.00 23.43 23.94 19.12
Cost (AU$/kg) 0.66 0.66 0.63 0.68 Cost (FJ$/kg) 0.80 0.08 0.76 0.83
The proximate analyses of the experimental diets are shown in Table 11. The crude
protein was 30 % for all the diets. The crude fat content was 10 % for all the diets.
The crude fibre ranged from 6.16 to 7.81 % with MFM2 showing higher level and
MBM3 showing the lowest. The gross energy ranged from 19.09 to 19.59 MJ/kg
with MBM3 showing highest gross energy content and MFM2 showing the lowest.
Table 11. Proximate composition of experimental diets (Winfeed Stochastic Formulation % DM
basis) (Experiment 1).
Components Control MBM1 MBM2 MBM3 MFM1 MFM2 Dry matter 93.82 93.67 92.40 91.40 93.24 94.19 Protein 30.00 30.00 30.00 30.00 30.00 30.00 Lipid 10.00 10.00 10.00 10.00 10.00 10.00 Ash 11.21 11.09 9.32 9.27 11.28 11.51 Crude Fibre 7.46 7.32 7.02 6.16 7.00 7.81 Gross Energy (MJ/kg)
19.12 19.14 19.53 19.59 19.17 19.09
Cost (AU$/kg) 0.55 0.54 0.54 0.53 0.55 0.57 Cost (FJ$/kg) 0.94 0.95 0.95 0.95 0.74 0.69
39
Note: MBM1, MBM2, MBM3 represent deferent meat bone meal inclusion levels. MFM1 and MFM2
represent different meat fish meal inclusion levels.
4.1.1.2 Growth performance, survival rate and feed intake
There was no difference (p ≤ 0.05) with regards to animal performance. Weight gain
ranged from 0.55 ± 0.43 to 1.27 ± 0.48 g. In terms of value, highest weight gain was
achieved by prawns fed the control diet. Total body length gain ranged from 7.06 ±
1.18 to 10.30 ± 2.03 mm with highest value amongst treatment shown for MFM1diet.
Survival ranged from 63.33 ± 3.33 to 86.66 ± 13.33 % with highest value of survival
seen in prawns fed MBM3 diet. The feed intake (Table 12; Annex 1 Fig. 7) among
all treatments presented no significant differences (p ≤ 0.05).
Figure 6. Mean weight gain, total body length gain and survival (%) (± s.d) for M. rosenbergii fed
six different diets for 21 d (Experiment 1).
Generally, the protein quality of dietary ingredients affects growth performance.
Protein quality of dietary protein sources depends on the amino acid composition and
their digestibility. Deficiency of an essential amino acid leads to poor utilization of
the dietary protein and thus reduces growth and decreases feed efficiency (Halver
and Hardy, 2002). Hossain and Islam (2007) found out that PL’s of M. rosenbergii
raised in a recirculation system for 60 days and fed a commercial shrimp nursery diet
(30 %) achieved survival of 76 % and SGR of 3.28 %/day. The use of different
protein sources in various combinations have been found to be more effective than
0
20
40
60
80
100
120
Control MBM1 MBM2 MBM3 MFM1 MFM2
Perc
enta
ge (%
)
Diets
% Weight gain % Total Body Length gain % Survival
40
that of a single source in the substitution of fishmeal in feeds by preventing the high
inclusion level of any single anti-nutrient in the diet (Hossain and Jauncey, 1990).
Yang et. al. (2004) on Macrobrachium nipponense and Zhu et. al. (2004) on
Liptopenaeus vannamei juveniles, both authors reported no significant differences in
growth when fed diets with varying inclusion levels (0-60 percent) of two protein
sources: fish and meat-bone meal. However, in separate studies conducted on
juveniles by Hossain et. al. (2007) on M. rosenbergii and Kureshy et. al. (2000) on
red drum fish, both reported that growth was negatively affected by meat-bone meal
when the fish meal replacement levels were above 14 and 17 percent, respectively.
Similarly, Forster et. al., (2003) reported that replacement of fish meal by meat-bone
meal above 25 percent reduced growth performance of Liptopenaeus vannamei.
The specific growth rate (SGR) for prawns in the different treatments ranged from
0.81 ± 0.36 to 1.45 ± 0.08 %/day. Hari and Kurup (2003a) obtained the highest SGR
(3.72 %/ day) of M. rosenbergii with diets containing 30% protein and varying
amounts of trash fishmeal and groundnut oilcake.
Figure 8. Experiment 1 specific growth rate (± s.d) of the M. rosenbergii fed six different diets for 21
d (Experiment 1).
0.000.200.400.600.801.001.201.401.601.802.00
Control MBM1 MBM2 MBM3 MFM1 MFM2
SGR
(%/d
ay)
Diets
41
Tab
le 1
2. M
ean
grow
th p
erfo
rman
ce, s
urvi
val a
nd fe
ed in
take
of M
. ros
enbe
rgii
fed
six
diff
eren
t die
ts o
f var
ying
incl
usio
n le
vels
of m
eat b
one
mea
l and
mea
t fis
h m
eal f
or 2
1 d
(n =
10)
. Val
ues (
Mea
n ±
SE) (
Expe
rim
ent 1
). Pa
ram
eter
s C
ontr
ol
MBM
1 M
BM2
MBM
3 M
FM1
MFM
2 F
P va
lue
Initi
al w
eigh
t (g)
4.
00 ±
0.2
0 4.
01 ±
0.0
7 3.
08 ±
0.2
4 3.
57 ±
0.1
1 3.
14 ±
0.5
5 2.
86 ±
0.1
9 3.
20
0.05
Fi
nal w
eigh
t (g)
5.
28 ±
0.3
0 4.
77 ±
0.2
8 3.
70 ±
0.2
4 4.
82 ±
0.3
5 4.
25 ±
0.7
1b
3.48
± 0
.20
3.26
0.
04
Wei
ght g
ain
(g)
1.27
± 0
.48
0.75
± 0
.35
0.55
± 0
.43
1.24
± 0
.26
1.11
± 0
.16
0.62
± 0
.03
0.91
0.
51
Car
apac
e le
ngth
gai
n (m
m)
3.65
± 0
.52
1.99
± 0
.37
2.61
± 0
.57
3.22
± 0
.14
3.58
± 1
.42
2.27
± 0
.11
1.04
0.
44
Abd
omen
leng
th g
ain
(mm
) 4.
42 ±
0.7
1 5.
06 ±
0.8
4 4.
85 ±
1.0
0 5.
45 ±
0.4
9 6.
72 ±
0.7
2 5.
21 ±
0.7
6 1.
04
0.44
To
tal B
ody
leng
th g
ain
(mm
) 8.
08 ±
1.0
6 7.
06 ±
1.1
8 7.
47 ±
1.5
4 8.
67 ±
0.5
2 10
.30
± 2.
03
7.49
± 0
.65
0.86
0.
53
Surv
ival
(%)
63.3
3 ±
8.82
63
.33
± 3.
33
86.6
6 ±
13.3
3 86
.66
± 6.
67
70.0
0 ±
10.0
0 80
.00
± 0.
00
1.74
0.
20
SGR
(%/d
ay)
1.31
± 0
.49
0.81
± 0
.36
0.88
± 0
.60
1.41
± 0
.23
1.45
± 0
.08
0.94
± 0
.06
0.64
0.
67
Feed
Inta
ke (g
/day
) 1.
09 ±
0.0
5 1.
08 ±
0.0
2 0.
78 ±
0.0
9 1.
19 ±
0.0
4 0.
91 ±
0.1
4 0.
79 ±
0.0
3 5.
377
0.07
FC
R
0.86
± 0
8 1.
44 ±
2.5
3 1.
42 ±
4.3
5 0.
96 ±
0.2
1 0.
82 ±
0.0
3 1.
27 ±
0.0
8 0.
84
0.55
42
4.1.1.3 Water quality parameters
In Experiment 1, there were no statistically significant differences in temperature and
D.O among treatments. The water temperature ranged from 27.80 ± 0.09 to 28.07±
0.03 ºC, D.O from 7.14 ± 0.04 to 7.24 ± 0.01 mg/L and pH from 7.4 to 7.5. All
nitrates, nitrites and ammonia levels were <0.2 mg/L (Table 13; Annex 1 Fig. 9). M.
rosenbergii can tolerate a wide range of temperature (14- 35 º C) and a wide range of salinity
levels (0-25 ppt). For growth, the optimal temperature is 29-31 º C, the optimal pH is
7.0-8.5, and the optimal salinity is 0-10 ppt (New, 1995). The effect of pH,
temperature and salinity on the oxygen consumption and nitrogen excretion on M.
rosenbergii has been studied by Nelson et. al., (1977) and by Chen and Kuo (1996).
Enterococcus infection in M. rosenbergii is exacerbated by high pH (8.8-9.5) and
high temperature (33-34 º C), but reduced by low salinity (5-10ppt) (Cheng and
Chen, 1998).
Table 13. Average water temperature and dissolved oxygen different diets for 21 d (Experiment 1).
4.1.2 Experiment 2
4.1.2.1 Proximate analysis
The proximate analyses of the experimental ingredients are shown in Tables 14. The
crude protein ranged from 16.47 to 23.19 % (dry weight) with copra meal showing
highest crude protein content and wheat showing lowest. The crude fat ranged from
4.10 to 13.20 % with copra meal showing highest crude fat content and mill mix
showing lowest. The gross energy ranged from 18.52 to 19.95 MJ/kg with copra
meal showing highest gross energy and wheat showing lowest.
Diets Temperature (ºC)
D.O (mg/L)
Control 27.80 ± 0.09 7.14 ± 0.04 MBM1 27.93 ± 0.02 7.18 ± 0.01 MBM2 27.87 ± 0.03 7.17 ± 0.01 MBM3 27.93 ± 0.03 7.20 ± 0.02 MFM1 27.98 ± 0.04 7.22 ± 0.01 MFM2 28.07 ± 0.03 7.24 ± 0.01 F-value 3.95 2.77 P value 0.20 0.07
43
Table 14. Proximate composition of ingredients (Winfeed Stochastic Formulation % DM basis.
(Experiment 2).
Components Wheat Copra meal Pea meal Mill mix Dry matter 89.00 97.30 90.00 87.50 Protein 16.47 23.19 18.50 17.63 Lipid 1.90 13.20 1.50 4.10 Ash 1.70 5.70 2.80 4.20 Gross Energy (MJ/kg)
18.52 19.95 18.76 19.28
Cost (AU$/kg) 0.68 0.48 0.46 0.29 Cost (FJ$/kg) 0.83 0.58 0.55 0.35
The proximate analyses of the experimental diets are shown in Table 15. The crude
protein was 30 % for all the diets. The crude fat content was 10 % for all the diets.
The crude fibre ranged from 3.49 to 17.98 % with Crest Tilapia Pellet (CTP)
showing higher level and Copra (CP) showing the lowest. The gross energy ranged
from 17.13 to 18.30 MJ/kg with CTP showing highest gross energy content and CP
showing the lowest.
Table 15. Proximate composition of experimental diets (Winfeed Stochastic Formulation % DM basis
(Experiment 2).
Components WHT MM1 MM2 CP PM CTP Dry matter 88.26 91.75 92.54 89.72 89.20 89.10 Protein 30.00 30.00 30.00 30.00 30.00 31.00 Lipid 10.00 10.00 10.00 10.00 10.00 4.60 Ash 12.03 11.98 12.13 13.55 11.38 11.20 Crude Fibre 4.16 5.94 6.25 3.49 9.18 17.98 Gross Energy (MJ/kg)
17.79 17.92 17.18 17.13 17.60 18.30
Cost (AU$/kg) 0.79 0.58 0.59 0.62 0.72 0.89 Cost (FJ$/kg) 0.96 0.71 0.72 0.75 0.87 1.08
Note: MM1 and MM2 represent different mill mix inclusion levels. CP and PM represent copra meal
and pea meal inclusion level respectively, CTP refers to Crest Tilapia Pellet.
44
4.1.2.2 Growth performance, survival rate and feed intake
There was no statistically significant difference (P≤ 0.05) with regard to growth
performance, survival rate and feed intake among the treatments. Weight gain ranged
from 2.16 ± 0.54 to 7.04 ± 2.96 g. Total body length gain ranged from 3.04 ± 1.21 to
10.25 ± 2.47 mm. Survival ranged from 54.16 ± 18.16 to 79.16 ± 8.33 %. Increasing
the carbohydrate in the diet enhances growth to a point. This is attributed to the
protein sparing effect of carbohydrate in which the higher level of carbohydrate in
the diet provided more energy required for the metabolic activities of the animal,
while sparing more protein for growth. According to Andrews et. al. (1972), for
Penaeus aztecus the protein sparing effect of carbohydrate in diets occurs at a 30
percent level. Similarly, Sick and Andrews (1973) found that 40 percent corn starch
in casein-based diets produced faster growth in P.duorarum. Further, at lower protein
levels, energy may be partly derived from protein, thus accounting for lower growth
even if protein and lipid levels in the diets at lower and higher carbohydrates were
the same.
Figure 10. Mean % (± s.d) weight gain, total body length gain and survival of M. rosenbergii fed six different diets for 28 d (Experiment 2).
0
20
40
60
80
100
WHT MM1 MM2 CP PM CTP
Perc
enta
ge (%
)
Diets
% Survival % Weight gain % Total Body length gain
45
Tab
le 1
6. M
ean
grow
th p
erfo
rman
ce, s
urvi
val a
nd fe
ed in
take
of M
. ros
enbe
rgii
fed
four
diff
eren
t die
ts o
f cop
ra m
eal,
mill
mix
and
pea
mea
l for
28
d.
Val
ues (
Mea
n ±
SE).(
Exp
erim
ent 2
).
Para
met
ers
WH
T
MM
1 M
M2
CP
PM
CT
P F
P va
lue
Initi
al w
eigh
t (g)
5.
30 ±
0.6
9 5.
40 ±
0.8
5 6.
46 ±
1.2
1 9.
15 ±
0.4
7 8.
43 ±
1.1
5 6.
73 ±
0.9
0 2.
98
0.05
Fi
nal w
eigh
t (g)
7.
46 ±
1.1
6 7.
63 ±
1.4
9 10
.73
± 1.
18
12.4
2 ±
0.52
11
.8 ±
0.9
8 13
.77
± 3.
70
2.01
0.
14
Wei
ght g
ain
(g)
2.16
± 0
.54
2.24
± 0
.66
4.26
± 2
.37
3.27
± 0
.06
3.37
± 0
.30
7.04
± 2
.96
1.28
0.
33
Car
apac
e le
ngth
gai
n (m
m)
0.47
± 0
.27
1.39
± 0
.53
2.60
± 1
.83
1.37
±0.
50
2.31
± 0
.59
4.74
±1.
94
1.48
0.
26
Abd
omen
leng
th g
ain
(mm
) 3.
46 ±
2.0
1 1.
64 ±
0.7
1 5.
03 ±
3.9
4 2.
39 ±
0.46
2.
97 ±
1.15
5.
51 ±
0.6
2 0.
66
0.65
To
tal B
ody
leng
th g
ain
(mm
) 4.
76 ±
2.2
4 3.
04 ±
1.2
1 7.
63 ±
5.7
3 3.
76 ±
0.5
8 5.
28 ±
1.4
5 10
.25
± 2.
47
0.85
0.
53
Surv
ival
(%)
58.3
3 ±
23.2
0 66
.66
± 8.
33
54.1
6 ±
22.0
5 79
.16
± 8.
33
54.1
6 ±
18.1
6 62
.50
± 25
.00
0.25
0.
92
SGR
(%/d
ay)
1.20
± 0
.16
1.20
± 0
.15
1.91
± 1
.12
1.09
± 0
.03
1.25
± 0
.24
2.38
± 0
.53
1.00
0.
46
Feed
inta
ke (g
/day
) 0.
53 ±
1.1
3 0.
67 ±
0.3
2 0.
70 ±
1.0
4 1.
75 ±
0.2
2 1.
09 ±
0.6
5 1.
31 ±
1.1
9 0.
32
0.88
FC
R
0.25
± 0
.04
0.30
± 0
.05
0.16
± 0
.14
0.54
± 0
.04
0.32
± 0
.11
0.19
± 0
.09
2.61
0.
08
46
The feed intake (Table 16; Annex 1 Fig 11) among all treatments did not present
statistically significant differences (p ≤ 0.05). Although in terms of value, higher feed
intake was seen for prawns fed diet CP diet. The specific growth rate (SGR) for
prawns in the different treatments ranged from 1.09 ± 0.03 to 2.38 ± 0.53 %/day.
Figure 12. Specific growth rate (± s.d) of M. rosenbergii fed six different diets for 28 d (Experiment
2).
4.1.2.3 Water quality parameters
In Experiment 2, all water parameters did not show statistically significant
differences (P ≤ 0.05) for temperature and dissolved oxygen among the treatments.
The water temperature ranged from 27.88 ± 0.04 to 27.99 ± 0.03 ºC, D.O. from 7.15
± 0.03 to 7.22 ± 0.01 mg/L and pH from 7.3 to 7.5. All nitrates, nitrites and
ammonia levels were <0.2 mg/L (Table 17; Annex 1 Fig. 13).
Table 17. Average temperature and dissolved oxygen for the
M. rosenbergii fed six diets for 28 d (Experiment 2).
Diets Temperature (ºC)
D.O. (mg/L)
WHT 27.93 ± 0.03 7.15 ± 0.03 MM1 27.91 ± 0.02 7.18 ± 0.003 MM2 27.94 ± 0.05 7.20 ± 0.01 CP 27.89 ± 0.02 7.22 ± 0.01 PM 27.88 ± 0.04 7.21 ± 0.01 CTP 27.99 ± 0.03 7.21 ± 0.02 F value 2.74 2.54 P value 0.07 0.08
Therefore, the findings of these two experiments indicate that the ingredient
inclusion level for selected local ingredients available in Fiji showed no significant
differences in the intake level for the two batches of selected local ingredients. The
0.00
1.00
2.00
3.00
4.00
WHT MM1 MM2 CP PM CTP
SGR
(%/d
ay)
Diets
47
omnivore nature of freshwater prawns permits the use of a wide variety of locally
available ingredients including commercial by-products as ingredients in formulated
feeds. This suggests that inclusion levels for feeds formulation of diets for freshwater
prawn M .rosenbergii could be quite flexible.
4.2 Experiment in grow out ponds- comparing two experimental formulations against two commercial feeds
4.2.1 Proximate analysis
The proximate analyses of the experimental and commercial diets are shown in Table
18. The crude protein was around 32 % for the experimental diets and 22.8 % for
Crest Tilapia Pellet (CTP) and 30.3 % for Pacific Prawn Pellet (PPP). The crude fat
content was 10.2 % for Diet 1 and 11.5 % for Diet 2. The gross energy ranged from
18.2 to 19.3 MJ/kg with Diet 1 showing highest gross energy content and CTP
showing the lowest.
Table 18. Proximate compositions of experimental diets and commercial diets (% DM basis)
(Experiment 3).
Components Diet 1 Diet 2 CTP PPP Dry matter 90.1 94.9 90.2 91.0 Ash 13.1 11.2 10.9 12.3 Crude protein 32.8 32.2 22.8 30.3 Lipids 10.2 11.5 5.3 8.7 GE MJ/kg 19.3 20.1 18.2 19.2 FJ$/kg 1.08 0.71 1.20 1.52 AU$/kg 0.58 0.38 0.64 0.81
4.2.2 Growth performance, survival rate and feed intake
The evaluation of M. rosenbergii growth performance, survival rate and feed intake
in the different diet treatments are summarized in Table 19. Growth performance,
survival rate and fed intake of prawns fed the four experimental diets were not
significantly different among treatments. This noticeable similarity can be explained
by the high variation within the experimental groups. From highest to lowest in
weight gain (g) order it was observed that Diet 1> Pacific prawn pellet > Crest tilapia
pellet >Diet 2. An FCR of 0.97± 0.01 was obtained for Diet 1, followed by the PPP
of 1.09 ± 0.12, CTP of 1.10 ±0.06 and Diet 2 of 1.14 ±0.02. The mean weight gain
values ranged between 6.06 ± 1.50 to 9.28 ± 0.42 g. The mean SGR values of prawns
48
in different treatments ranged between 1.94 ± 0.28 to 2.27 ± 0.07 %/day. The FCR
values ranged between 0.97 ± 0.02 to 1.16 ± 0.08. The PER values ranged between
2.79 ± 0.32 to 3.99 ± 0.20. Survival (%) of prawns varied between 83.05 ± 3.22 and
88.84 ± 0.48 %. New and Singholka (1985) suggested that a survival rate above 50
percent between stocking and harvesting is acceptable. According to D’ Abramo et.
al. (1989), survival rate of giant freshwater prawn in earthen ponds ranged from 54
to 89 percent. Daniels et. al. (1995) also reported the survival rate of prawns in
earthen ponds fed a specifically formulated diet to be 74 to 82 percent. Survival has
more to do with the cannibalistic nature of the prawns, the male hierarchy and
predation than feed. Different stocking densities used for all diets did not show any
difference in either growth performance or survival.
The protein content and quality of the feed eaten is an important factor for growth. In
terms of how fast prawns grow will depend not only on the amount eaten but the
quality of the ingredients providing the animal with the necessary nutrients and in the
right quantities. The growth of M. rosenbergii individuals within a population is
highly variable and this may be due to genetics, social structure and environmental
factors. Several authors (Wickins, 1972; Forster and Beard, 1974; Raanan, 1983;
Raanan, 1985) suggested that about half of the M. rosenbergii population grow
rapidly while the other half grows slowly and uniformly. However, more accurate
results in terms of growth performance can be obtained by more specific
measurements, such as individual stocking, i.e. individual weights recorded instead
of a random sampling assuming homogeneity of weight in the group taking into
consideration that M. rosenbergii has a territorial behavior and its population does
not grow in a uniform way.
49
Tab
le 1
9. M
ean
(± s.
e) g
row
th a
nd fe
ed u
tiliz
atio
n fo
r M. r
osen
berg
ii fe
d fo
ur d
iffer
ent e
xper
imen
tal d
iets
in a
pon
d ex
perim
ent c
ondu
cted
for 1
24 d
(Exp
erim
ent 3
).
D
iet 1
D
iet 2
C
TP
PPP
F P
valu
e
Initi
al w
eigh
t (g)
0.
083
0.08
3
0.08
3
0.08
3
- -
Fina
l wei
ght (
g)
9.36
± 0
.42
6.14
± 1
.50
7.24
± 1
.81
8.95
± 0
.65
1.47
0.
29
Wei
ght g
ain
(g)
9.28
± 0
.42
6.06
± 1
.50
7.15
± 1
.81
8.87
± 0
.65
1.47
0.
29
Fee
d in
take
124
d
7381
± 8
45.4
0 54
78 ±
106
3.30
62
11 ±
149
4.58
81
62 ±
123
9.95
1.
02
0.43
Feed
inta
ke 1
24 d
/ani
mal
8.
96 ±
0.3
5 6.
94 ±
1.9
6 7.
81 ±
1.8
2 9.
60 ±
0.3
9 0.
76
0.55
Prot
ein
inta
ke 1
24 d
24
16 ±
276
.78
1763
± 3
42.1
4 14
17 ±
341
.00
2469
± 3
75.3
3 2.
33
0.15
Prot
ein
inta
ke 1
24 d
/ani
mal
2.
93 ±
0.1
1 2.
23 ±
0.6
3 1.
78 ±
0.4
2 2.
90 ±
0.1
2 2.
10
0.18
SGR
(%/d
ay)
2.25
± 0
.01
1.78
± 0
.16
1.94
± 0
.16
2.21
± 0
.02
1.74
0.
24
FCR
0.
97 ±
0.0
1 1.
14 ±
0.1
2 1.
10 ±
0.0
6 1.
09 ±
0.0
2 0.
93
0.47
PER
3.
17 ±
0.0
4 2.
79 ±
0.3
2 3.
99 ±
0.2
0 3.
04 ±
0.2
2 5.
61
0.02
Surv
ival
(%)
86.6
8 ±
1.8
1 88
.84
± 0
.48
84.4
6 ±
2.2
2 83
.05
± 3
.22
1.37
0.
32
50
The increase in the stocking density of prawns in ponds from 5 PL/m2 which is the
usual practice to 7 and 9 PL/m2 did not seem to affect growth. Mires, 1987
successfully stocked M. rosenbergii juveniles at 5 to 7.5/m2 in polyculture with Nile
tilapia (Oreochromis niloticus).
Obtaining the best performing feed for the most economical price is a challenge.
Understanding the FCR is important. Growth studies and FCR vary according to
various factors including the nutritional and physical quality of feeds, environment
variants such as temperature, intensity of production (availability of natural feed) and
other factors including genetics and social structure. The average feed conversion in
the study was 1.08. Diet 1 obtained an FCR value of 0.97. Hossain et. al. (2000)
reported FCR value of 3.06-4.85 for prawns. Similarly, Daniels et. al. (1995)
reported FCR value of 2.18-2.43 and Sarma and Sahu (2002) recorded an FCR of
2.35 with a diet containing 37 percent protein for freshwater prawn M. rosenbergii.
Jayachandran (2001) stated that the rate of food consumption increases with
increasing prawn size up to a certain age. In addition, he reported a 10-18:1 FCR for
raw feeds and 2-3.5:1 for compound diets.
Figure 14. Feed conversion ratio (± s.d) for M. rosenbergii fed four different diets in the pond experiment conducted for 124 d (Experiment 3).
4.2.3 Pond Production: Experimental feed vs. Commercial feed
An average of 972 animals was stocked into each pond with a total weight of 83 g.
On average a total harvest of 6.5 kg of prawn was produced from each pond
therefore average feed conversion ratio was estimated at 1.08 kg of feed per kg of
prawns produced.
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
Diet 1 Diet 2 CTP PPP
FCR
Diets
51
There were 2484 prawns fed Diet 1 with this group having a total initial weight of
206 g. After 124 days of experiment using 22.14 kg of feed, a harvested value of
23.25 kg was achieved with an FCR value of 0.97 obtained.
A total of 2530 prawns were fed Diet 2 having an initial weight of 210 g. After 124
days, this group consumed 16.44 kg of feed. A harvest of 15.53 kg was obtained with
an FCR value of 1.14 achieved by this group.
The Crest tilapia diet was tested on 2849 prawns with a total biomass of 236 g.
Prawns in this group consumed a total of 18.63 kg of feed with a harvest of 20.63 kg
and an FCR value of 1.10.
The Pacific Prawn diet was tested on 3076 prawns having a total biomass of 255 g.
This group consumed 24.49 kg of feed and a harvest of 22.66 kg was achieved with
an FCR value of 1.09 obtained.
Animals fed with Diet 1, showed slightly better results in terms of value for all
growth parameters measured, having an average of 33% (9.28 g) better weight gain
than Diet 2 (6.06 g) and 22% better than Diet 3 (7.15 g) (Fig. 15). Diet 1 and
commercial Pacific prawn diet showed very similar weight gain results (9.28 g and
8.87 g) respectively.
Figure 15. Average weight M. rosenbergii fed four different diets in the pond experiment conducted for 124 d (CTP: Crest tilapia pellet and PPP: Pacific prawn pellet) (Experiment 3).
0
1
2
3
4
5
6
7
8
9
10
Initial 1 2 3 4
Ave
rage
Wei
ght (
g)
Time (months)
Diet 1 Diet 2 CTP PPP
52
Daniels et. al., 1995 reported a production of 1041-1662 kg/ ha for M. rosenbergii
fed with formulated diet for a 130 day experimental period. William et. al., 1995
reported 1024-1662 kg/ha for freshwater prawn fed with formulated diet. The prawn
production for the 124 d culture period was similar for Diet 1 and Pacific Prawn diet
at 0.06 kg/m2, while Diet 2 at 0.04 kg/ m2 and Crest tilapia diet at 0.05 kg/ m2. Chand
et. al. (2000) obtained similar production of 1483 kg/ha fed a commercial pelleted
feed. The lower production figure in this study may be due to the fact that no
fertilization was added to the pond to enhance pond productivity because this factor
was assumed constant.
4.2.4 Production cost: experimental vs commercial feed
The production cost analysis for each diet is summarized in Table 20. The economic
analysis of M. rosenbergii production in the study during a 124 d culture period show
that Diet 1 which is cheaper cost (FJ$1.05) to produce 1 kg of prawn as compared to
the commercial diets Pacific Prawn feed (FJ$1.66) and Crest Tilapia feed (FJ$1.34).
The development of diets for M. rosenbergii prawns requires the fulfillment of the
nutritional requirements. The omnivore nature of the freshwater prawn allows the use
of a wide variety of locally available feedstuffs including commercial by-products as
ingredients in formulated diets. To create a balanced diet, it is necessary to establish
the minimum protein level to provide essential amino acids (Guillaume 1997; Tacon
and Akiyama 1997). Based on growth, yield and feed cost it can be suggested that
the experimental Diet 1 may be recommended for semi-intensive farmers for
monoculture of M. rosenbergii in ponds being comparable to both commercial Diets
(Pacific Prawn and Crest Tilapia feed) in Fiji. It is also recommended that this
formula may be used to boost growth in the later stages, therefore more utilization of
primary productivity through efficient fertilization during the early stages to reduce
feed cost for farmers.
53
Tab
le 2
0. C
ompa
rison
of e
xper
imen
tal f
eed
and
com
mer
cial
feed
for M
. ros
enbe
rgii
pond
nut
ritio
n ex
perim
ent c
ondu
cted
for 1
24 d
(Exp
erim
ent 3
).
D
iet 1
D
iet 2
C
TP
PPP
F P
valu
e
Initi
al N
o.
2.8
80 ±
141
.92
2853
± 1
97.6
6 28
49 ±
116
.18
3076
± 1
50.9
2 0.
05
0.98
Fina
l No.
24
84 ±
108
.10
2530
± 1
71.0
9 28
49 ±
89.
31
2532
± 1
06.4
0 0.
03
0.99
Initi
al w
eigh
t (g)
23
9 ±
1.71
23
7 ±
3.68
23
6 ±
2.99
25
5 ±
8.82
1.
46
0.10
Fina
l wei
ght (
g)
2325
0 ±
448.
27
1553
4 ±
1228
.55
2062
7 ±
1992
.83
2266
1 ±
775.
38
1.99
0.
19
Prod
uct (
g)
2301
1 ±
446.
65
1529
7 ±
1224
.88
2039
0 ±
1990
.98
2240
6 ±
768.
66
1.96
0.
20
Tota
l Fee
d (k
g)
22.1
4 ±
8.45
16
.44
± 10
.63
18.6
3 ±
14.9
5 24
.49
± 12
.39
1.02
0.
43
FJ$
of d
iet
1.08
0.
71
1.21
1.
52
- -
AU
$ of
die
t 0.
58
0.38
0.
64
0.81
-
-
FJ$
tota
l fee
d
24.0
0 ±
17.6
4 11
.55
± 8.
56
22.5
4 ±
15.0
2 37
.22
± 28
.78
0.81
0.
52
AU
$ to
tal f
eed
12.7
7 ±
9.40
6.
17 ±
4.5
6 12
.00
± 8.
00
19.8
1 ±
15.3
2 0.
81
0.52
FJ$
prod
uce
1kg
praw
n 1.
05 ±
0.1
4 0.
80 ±
0.1
4 1.
34 ±
0.1
2 1.
66 ±
0.3
3 0.
83
0.51
AU
$ pr
oduc
e 1k
g pr
awn
0.56
± 0
.08
0.43
± 0
.08
0.71
± 0
.07
0.88
± 0
.09
0.80
0.
53
54
4.2.5 Water Quality Parameters
During the experimental period water temperature ranged from 28.23 ± 0.03 to 28.29
± 0.02 ºC (Table 21); dissolved oxygen varied between 8.97 ± 0.10 to 9.13 ± 0.16
mg/L and pH ranged between 7.75 ± 0.06 to 7.79 ± 0.02. The water parameters
showed no significant differences during the culture period and fall within the
suggested ranges for prawn culture having no negative effect on the growth of
prawns.
Table 21. Water quality values monitored during the M. rosenbergii pond nutrition experiment conducted for 124 d (Experiment 3).
Components Temp (ºC) D.O. (mg/L) pH Diet 1 28.3 ± 0.04 9.3 ± 0.14 7.74 ± 0.10 Diet 2 28.3 ± 0.02 9.2 ± 0.16 7.75 ± 0.00 CTP 28.3 ± 0.03 9.0 ± 0.16 7.80 ± 0.02 PPP 28.2 ± 0.03 9.2 ± 0.23 7.78 ± 0.00 F value 2.41 0.39 0.34 P value 0.21 0.77 0.80
55
5.0 CONCLUSIONS AND RECOMMENDATIONS
The current commercially available feeds are at present inconsistent in supply and
too costly for farmers to purchase. The idea was to produce a diet using locally
available ingredients to be easily prepared by farmers as “on farm- feeds” and in the
future suggested to commercial feed companies to produce and supply. Locally
available ingredients were identified such as fish meal, meat bone meal, meat fish
meal, copra meal, wheat, mill mix, rice meal and pea meal. The assessment of
selected ingredients locally available in Fiji showed that the inclusion of feed
ingredients for the formulation of diets for the giant freshwater prawn is flexible.
Commercially, the use of ingredients in formulated feed should be cost- effective and
should be available in large quantities in areas where culture operations occur. It is
not always necessary that the best diet will be the cheapest but it will produce better
growth and lower FCR values which will be more economical in the long- term. In
conclusion, the finding of this study is cost effective and efficient as a farm made
feed. A limited number of ingredients are used in the formulation of feeds in
aquaculture in Fiji. When formulating a diet for freshwater prawn, it is
recommended that ingredients be chosen based on nutritional value taking into
account the potential anti-nutritional factors rather than on basis of cost per unit
alone. Natural food in the pond may have satisfied part of the nutritional
requirements of the prawn. Thus, M. rosenbergii cultured in ponds can be fed a diet
containing a lower dietary protein levels and fish meal compared to prawns grown
indoors in tanks. It is recommended that future studies be conducted to determine the
extent in which natural foods contribute to the diet of M. rosenbergii and encourage
enhancing pond productivity to reduce feed costs. Understanding the bioenergetics of
the prawn and the interaction of dietary components is important in formulating
adequate diets. The ratio of protein to energy is important to consider in formulation
of cost effective environmentally friendly diets of prawns. Further research is needed
to determine the relevant dietary levels of P: E for all stages of prawns under
commercial culture conditions. It is recommended that this diet be further tested on
commercial prawn farms in Fiji and the region. There is also the need to further train
farmers on how to formulate and produce nutritionally balanced feeds. In addition,
Government should subsidize the cost of locally fabricated machines to make it
affordable to farmers so as to produce on farm made feeds.
56
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69
7.0 ANNEX
7.1 Annex 1
Plate 1. Experimental set up of recirculation system in the Seawater Wet Lab at USP. (Photo: Author)
Plate 2: Sieving ingredient (Photo: Author) Plate 3: Weighing ingredients (Photo: Author)
Plate 4: Combining ingredients Plate 5: Mixing ingredients with water
(Photo: Author) (Photo: Author)
70
Plate 6: Diet passes through Plate 7: Dried pellets (Photo: Author)
pellet machine (Photo: Author)
Plate 8: Diets stored in plastic bags Plate 9: Separated Diet rations
(Photo: Author) (Photo: Author)
Plate 10: Weighing out daily ration Plate 11: Vacuum Filtration apparatus
(Photo: Author) (Photo: Author)
71
Plate 12: Filtered uneaten feed Plate 13: Uneaten feed wrapped in foil
(Photo: Author) (Photo: Author)
Plate 14: Re-weighing prawn Plate 15: Measuring carapace length
(Photo: Author) (Photo: Author)
Plate 16: Measuring abdomen length
(Photo: Author)
72
Figure 7. Average food consumption of M. rosenbergii fed six different diets over
21 d (Experiment 1)
Figure 9. Average water quality parameter for feed intake over 21 d (Experiment 1).
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
3 6 9 12 15 18 21
Feed
con
sum
ed (g
/day
)
DaysControl MBM1 MBM2 MBM3 MFM1 MFM2
26.827.027.227.427.627.828.028.228.428.6
6.4
6.6
6.8
7.0
7.2
7.4
7.6
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
D.O
(mg/
L) a
nd p
H
Days
AM D.O. PM D.O. pH AM Temp PM Temp
Tem
perature (ºC)
73
Figure 11. Average food consumption of prawns fed six different diets over 28 d
(Experiment 2).
Figure 13. Average water quality parameters measured for the feed intake trial
over 28 d (Experiment 2).
0.00
0.50
1.00
1.50
2.00
2.50
3.00
4 8 12 16 20 24 28
Feed
con
sum
ed (g
/day
)
DaysWHT MM1 MM2 CP PM CTP
27
27.2
27.4
27.6
27.8
28
28.2
55.5
66.5
77.5
88.5
99.510
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Tem
perature ( ºC )
D.O
. (m
g/l)
and
pH
Time (days)
AM Temp AM D.O. PM D.O. pH PM Temp
74
Table 22. Experiment 1 single factor ANOVA of weight gain of M.rosenbergii
ANOVA- Weight Gain Source of Variation SS df MS F P-value F crit Between Groups 1.424 5 0.284 0.905 0.508 3.105 Within Groups 3.774 12 0.314 Total 5.198 17
Table 23. Experiment 1 single factor ANOVA of specific growth rate for M.rosenbergii
ANOVA- Specific Growth Rate Source of Variation SS df MS F P-value F crit Between Groups 1.256 5 0.251 0.640 0.673 3.105 Within Groups 4.707 12 0.392 Total 5.963 17
Table 24. Experiment 1 single factor ANOVA of carapace length gain for M. rosenbergii
ANOVA- Carapace Length Gain
Source of Variation SS df MS F P-value F crit Between Groups 7.244 5 1.448 1.041 0.437 3.105 Within Groups 16.699 12 1.391 Total 23.943 17
Table 25. Experiment 1 single factor ANOVA of abdomen length gain for M. rosenbergii
ANOVA- Abdomen Length Gain Source of Variation SS df MS F P-value F crit Between Groups 9.213 5 1.842 1.039 0.438 3.105 Within Groups 21.281 12 1.773 Total 30.495 17
Table 26. Experiment 1 single factor ANOVA of total body length gain for M .rosenbergii
ANOVA- Total Body Length Gain Source of Variation SS df MS F P-value F crit Between Groups 20.978 5 4.195 0.863 0.532 3.105 Within Groups 58.303 12 4.858 Total 79.282 17
Table 27. Experiment 1 single factor ANOVA of survival for M. rosenbergii
ANOVA- Survival Source of Variation SS df MS F P-value F crit Between Groups 1783.333 5 356.666 1.735 0.201 3.105 Within Groups 2466.666 12 205.555 Total 4250 17
75
Table 28. Experiment 1 single factor ANOVA of food consumed for M. rosenbergii
ANOVA- Food consumed
Source of Variation SS df MS F P-value F crit Between Groups 0.440309 5 0.088062 5.377 0.078 3.105 Within Groups 0.196518 12 0.016376 Total 0.636826 17
Table 29. Experiment 1 single factor ANOVA of temperature for M. rosenbergii
ANOVA- Temperature Source of Variation SS df MS F P-value F crit Between Groups 0.128 5 0.025 3.952 0.203 3.105 Within Groups 0.077 12 0.006 Total 0.205 17
Table 30. Experiment 1 single factor ANOVA of dissolved oxygen for M. rosenbergii
ANOVA- Dissolved Oxygen Source of Variation SS df MS F P-value F crit Between Groups 0.019 5 0.003 2.772 0.070 3.105 Within Groups 0.016 12 0.001 Total 0.036 17
Table 31. Experiment 2 single factor ANOVA of weight gain for M. rosenbergii
ANOVA- Weight Gain Source of Variation SS df MS F P-value F crit Between Groups 48.745 5 9.749 1.281 0.333 3.105 Within Groups 91.278 12 7.606 Total 140.024 17
Table 32. Experiment 2 single factor ANOVA of specific growth rate for M. rosenbergii
ANOVA- Specific Growth Rate Source of Variation SS df MS F P-value F crit Between Groups 4.075 5 0.815 0.995 0.460 3.105 Within Groups 9.829 12 0.819 Total 13.904 17
Table 33. Experiment 2 single factor ANOVA of carapace length gain for M .rosenbergii
ANOVA-Carapace Length Gain Source of Variation SS df MS F P-value F crit Between Groups 32.832 5 6.566 1.629 0.226 3.105 Within Groups 48.368 12 4.030 Total 81.201 17
76
Table 34. Experiment 2 single factor ANOVA of abdomen length gain for M .rosenbergii
ANOVA-Abdomen Length Gain Source of Variation SS df MS F P-value F crit Between Groups 35.559 5 7.111 0.646 0.669 3.105 Within Groups 132.027 12 11.002 Total 167.586 17
Table 35. Experiment 2 single factor ANOVA of total body length for M. rosenbergii
ANOVA-Total Body Length Gain Source of Variation SS df MS F P-value F crit Between Groups 108.891 5 21.778 0.910 0.506 3.105 Within Groups 287.080 12 23.923 Total 395.972 17
Table 36. Experiment 2 single factor ANOVA of Survival for M. rosenbergii
ANOVA-Survival Source of Variation SS df MS F P-value F crit Between Groups 1354.167 5 270.833 0.255 0.928 3.105 Within Groups 12708.33 12 1059.028 Total 14062.5 17
Table 37. Experiment 2 single factor ANOVA of food consumed for M. rosenbergii
ANOVA- Food consumed
Source of Variation SS df MS F P-value F crit Between Groups 3.565193 5 0.713039 0.329 0.88 3.10 Within Groups 25.96514 12 2.163761 Total 29.53033 17
Table 38. Experiment 2 single factor ANOVA of temperature for M. rosenbergii
ANOVA-Temperature Source of Variation SS df MS F P-value F crit Between Groups 0.048 5 0.009 2.745 0.070 3.105 Within Groups 0.042 12 0.003 Total 0.091 17
Table 39. Experiment 2 single factor ANOVA of dissolved oxygen for M. rosenbergii
ANOVA-Dissolved Oxygen Source of Variation SS df MS F P-value F crit Between Groups 0.010 5 0.002 2.544 0.085 3.105 Within Groups 0.009 12 0.000 Total 0.019 17
77
7.2 ANNEX 2
Plate 17: Grinding ingredients Plate 18: Weighing out ingredients
(Photo: Author) (Photo: Author)
Plate 19: Mixing ingredients Plate 20: Pelletizing diets
(Photo: Author) (Photo: Author)
Plate 21: Drying feeds in oven Plate 22: Packed feeds for storage
(Photo: Author) (Photo: Author)
78
Plate 23: Quarantine Facility Plate 24: Raceway used for stocking PL
(Photo: Author) (Photo: Author)
Plate 25: Post larvae at PL 14 Plate 26: Feed tray in raceway
(Photo: Author) (Photo: Author)
Plate 27: Complete pond draining Plate 28: Pond Liming
(Photo: Author) (Photo: Author)
79
Plate 29: Earthen ponds filled with water (Photo: Author)
Plate 30: Counting of PL (Photo: Author) Plate 31: PL stocking in pond (Photo: Author)
80
Table 40. Experiment 3 single factor ANOVA of weight gain for M. rosenbergii
ANOVA- Weight gain
Source of Variation SS df MS F P-value F crit Between Groups 20.27931 3 6.759771 1.473 0.293 4.066 Within Groups 36.71112 8 4.58889 Total 56.99043 11
Table 41. Experiment 3 single factor ANOVA of total feed intake for M. rosenbergii
ANOVA- Feed Intake 124 d
Source of Variation SS df MS F P-value F crit Between Groups 12857835 3 4285945 1.017 0.434 4.066 Within Groups 33699407 8 4212426 Total 46557242 11
Table 42. Experiment 3 single factor ANOVA of feed intake per animal for M .rosenbergii
ANOVA- Feed intake 124 d/animal
Source of Variation SS df MS F P-value F crit Between Groups 12.64969 3 4.216564 0.757 0.548 4.066 Within Groups 44.51653 8 5.564567 Total 57.16623 11
Table 43. Experiment 3 single factor ANOVA of protein intake for M. rosenbergii
ANOVA- Protein intake 124 d
Source of Variation SS df MS F P-value F crit Between Groups 2364749 3 788249.6 2.331 0.150 4.066 Within Groups 2704923 8 338115.4 Total 5069672 11
Table 44. Experiment 3 single factor ANOVA of protein intake per animal for M. rosenbergii
ANOVA- protein intake/ animal
Source of Variation SS df MS F P-value F crit
Between Groups 2.803025 3 0.9343417 2.102 0.178 4.066
Within Groups 3.555 8 0.444375
Total 6.358025 11
81
Table 45. Experiment 3 single factor ANOVA specific growth rate for M. rosenbergii
ANOVA-Specific growth rate
Source of Variation SS df MS F P-value F crit
Between Groups 0.452366667 3 0.1507889 1.739 0.236 4.066 Within Groups 0.693333333 8 0.0866667 Total 1.1457 11
Table 46. Experiment 3 single factor ANOVA of feed conversion ratio for M. rosenbergii
ANOVA- Feed conversion ratio
Source of Variation SS df MS F P-value F crit Between Groups 0.051292 3 0.0170972 0.933 0.468 4.066 Within Groups 0.1466 8 0.018325 Total 0.197892 11
Table 47. Experiment 3 single factor ANOVA of protein energy ratio for M.rosenbergii
ANOVA-protein energy ratio
Source of Variation SS df MS F P-value F crit Between Groups 2.417367 3 0.805789 5.609 0.022 4.066 Within Groups 1.1492 8 0.14365 Total 3.566567 11
Table 48. Experiment 3 single factor ANOVA of survival for M.rosenbergii
ANOVA- Survival
Source of Variation SS df MS F P-value F crit Between Groups 57.93691 3 19.3123 1.368 0.320 4.066 Within Groups 112.8742 8 14.10928 Total 170.8111 11
Table 49. Experiment 3 single factor ANOVA of temperature for M.rosenbergii
ANOVA-Temperature
Source of Variation SS df MS F P-value F crit Between Groups 0.005667 3 0.0019 0.798 0.528 4.066 Within Groups 0.018913 8 0.0024 Total 0.024579 11
82
Table 50. Experiment 3 single factor ANOVA of dissolved oxygen for M.rosenbergii
ANOVA-Dissolved Oxygen
Source of Variation SS df MS F P-value F crit Between Groups 0.045086 3 0.015028536 0.243 0.863 4.066 Within Groups 0.494555 8 0.061819375 Total 0.539641 11
Table 51. Experiment 3 single factor ANOVA of pH for M. rosenbergii
ANOVA-pH
Source of Variation SS df MS F P-value F crit Between Groups 0.003035 3 0.00101182 0.335 0.800 4.066 Within Groups 0.024095 8 0.00301182 Total 0.02713 11
Table 52. Crest Feed Mill Freshwater Prawn Formulation
Source: Crest Ltd, Nausori. Aquacubea is a type of binder used to maintain feed structure in water.
Table 53. Crest Feed Mill Proximate Composition of Tilapia Grower Pellet
Crude protein
Moisture Fat Fiber Ash
Stand. 24-26% 12-14% 3.5-5.5% 4.6-6.6% 4.6-6.6% Test 1 23.68 13.49 4.1 6.04 6.08 Test 2 25.06 13.56 4.88 5.13 5.9 Test 3 25.23 13.66 4.83 5.55 5.6 Average 24.66 13.57 4.60 5.57 5.86 Table 54. Crest Feed Mill Proximate Analysis of Freshwater Prawn Pellet
Infra Alyser analysis CP
(%) Moist %
Fat %
Fibre %
Ash %
Fines (%)
Hard 30s %
Hardness 60s %
Moist %
Stand. 31-33 12-14 5.2-7.2 2.3-4.3 7.2-9.2 <16 85-95 80-90 12-14 T1 32.23 12.26 7.17 2.67 8.67 0 88 78 13.1 T2 31.51 13.84 7.98 2.08 6.08 0 90 80 14.6 T3 31.89 14.45 6.95 2.66 7.85 0 94 88 14.5 Avg. 31.88 13.52 7.37 2.47 7.53 0 90.67 82 14.07
Ingredients Quantity/Batch (kg) RPAN Fish Premix 8 Salt 5 Aquacubea 5 Choline 3 Wheat 765 Soya 251 Mill mix 280 Fish meal 520 Offal 150 TOTAL 1966
83
