Nutritional physiology during developmentof Senegalese sole (Solea senegalensis)

L. Conceição, L. Ribeiro, S. Engrola, C. Aragão, S.Morais, M. Lacuisse, F. Soares and M.T. Dinis

Centre of Marine Sciences - CCMAR, University of Algarve, Faro, Portugal

• Senegalese sole (Solea senegalensis) is a species of high commercial interest in the South-Atlantic and Mediterranean areas

• Good model species to study larval nutritional physiology:

complex metamorphosisdifficulties in weaningoccasional problems of malpigmentationhigh incidence of skeletal deformities

Introduction

• Weaning - traditional bottleneck in sole culture

Late 90´s: • Improvement of zootechnical conditions • Technological improvements in inert diets

development of “soft” microagglomerate diets containing protein hydrolysates

• Weaning of Dover sole is no problem

• Reproducibility of good weaning results is still a problem in Senegalese sole (30 to 99% survival)

Introduction

Weaning problems in sole:

• Early metamorphosis

•Acquisition of a passive bottom-feeding behaviour

• Sole prefer “soft” dietary particles

Introduction

17 DAH

21 DAH

• Reviews recent findings in different aspects of nutritional physiology during the development of Senegalese sole

• How can we optimize the composition of sole weaning diets?

• Which are the limiting factors for weaning sole?

Objectives

Rearing sole

12 L:12 D

18-20°C

33-35‰

DAH0 403 18145 8

Rearing sole

12 L:12 D

18-20°C

33-35‰

DAH0 403 18145 8

Digestive capacity

0

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120

0 5 10 15 20 25 30 35

mU

/mg

prot

ein

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0.4

0.6

0.8

1

1.2

U/m

g pr

otei

n

Senegalese sole Sea bass Blackspot seabream Gilthead seabream

Trypsin specific activity

Ribeiro et al. (1999)

Digestive capacity

150 μl [U-14C] protein hydrolysate

- 40 ml seawater (34 ppt; 28ºC)

- ca. 10,000 Artemia metanauplii

- 14 h

* Morais et al. (2004) Aquaculture 231: 469-487

00,10,20,30,40,50,60,70,80,91

Air

0.5 M KOH

14CO2

H+

24h Incubation

Incubation water

Drawing: Sigurd Tonheim & Ivar Rønnestad

(Evacuation)

(Catabolism)

(Retention in tissues)

14C-AA

12, 22 e 35 DAH

(20-30 min.)

Artemia protein utilisation

Digestive capacityArtemia protein utilisation

12 DAH 22 DAH 35 DAH0

20

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Rad

iola

beli

nea

chco

mpa

rtm

ent(

% o

ftot

al r

adio

labe

lfed

)Body

Gut

Met. Trap

Watera b ab

ab

b

a

bab

Morais et al.(2004)

• Digestive enzymes activity and tracer studies using 14C-Artemia show that sole larvae, even at young stages, have a high capacity for digesting live preys

• This is reflected in a high growth potential and low mortality rates for this species during the larval stage compared to other marine fish species

• A major difference with other marine species, is the apparent absence of a true acidic digestion in the stomach

Digestive capacity

WeaningSudden weaning vs. co-feeding

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Artemia Co-Feeding Weaning 40DAH

Weaning 60DAH

Dry

wei

ght (

mg)

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Engrola et al. (2005)

10 mg 10 mg 13 mgSize at weaning

WeaningSudden weaning vs. co-feeding

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Artemia Co-Feeding Weaning 40DAH

Weaning 60DAH

Dry

wei

ght (

mg)

39 DAH60 DAH92 DAH

Survival rates over 90%

Engrola et al. (2005)

10 mg 10 mg 13 mgSize at weaning

Weaning

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1mg 2mg 4mg

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0102030405060708090

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rviv

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aa

• Sudden weaning

Engrola et al. (2005)

Weaning

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rviv

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• Sudden weaning • 5 days co-feeding

Engrola et al. (2005)

Weaning

• 5 to 10mg DW is a suitable window to start weaning Senegalese sole

• Sudden weaning of fish smaller than 5mg DW does not seem to work in Senegalese sole

• Early weaning (< 5mg DW) in co-feeding may improve survival rates but at the expense of lower growth rates and higher size dispersion

•There is probably variation in the adaptation capacity of individual larvae to inert microdiets.

Sampling: 24h

Incubation seawater

00,10,20,30,40,50,60,70,80,91

Airsupply

0.5 M KOH

14CO2 trap

H+

Drawing by Sigurd Tonheim & Ivar Rønnestad

(Evacuation)

(Catabolism)

(Tissue retention)

Drawing by Ivar Rønnestad

Absorption of 14C lipids

• TRI – Triolein• PC – Phosphatidylcholine-

1,2-dioleoyl• OA - Oleic Acid• SA - Stearic Acid• DHA

Lipids

Morais et al. (2005)

LipidsAbsorption of 14C lipids

Morais et al. (2005)

TRI PC OA SA DHA0

20

40

60

80

100

% A

bsor

bed

a

b

bx

y

xTRI – TrioleinPC – Posphatidylcholine

-1,2-dioleoylOA - Oleic AcidSA - Stearic AcidDHA

Drawing by Ivar Rønnestad

Lipids

• Fatty acid absorption efficiency increases with unsaturation and sole larvae spare DHA from catabolism

• Absorption efficiency in sole is highest for free FA, lowest for triacylglycerols and intermediate for phospholipids

• High dietary neutral lipid (soybean oil) results in reduced growth, and affects the capacity of Senegalese sole larvae to absorb and metabolize dietary fatty acids and amino acids

4 8 12 16 20Sole post-larvae (% IAA)

0

5

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25Artemia metanauplii (% IAA)

His

Cys

Lys

Leu

Phe

Arg

Met

Tyr

IleVal

Thr

Aragão et al. (2004)

Protein and amino acids

(30 min.)

32 DAH

14C-labels tube-fed with:

- Saline

- Saline + Phe + Leu

Sampling: 24h

Incubation seawater

00,10,20,30,40,50,60,70,80,91

Airsupply

0.5 M KOH

14CO2 trap

H+

Drawing by Sigurd Tonheim & Ivar Rønnestad

(Evacuation)

(Catabolism)

(Tissue retention)

Drawing by Ivar Rønnestad

Tube feeding trial

Protein and amino acidsAmino acid utilization

Control Leu + PheSupplement

0

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% o

f inj

ecte

d la

belle

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A

Post-larvae32 DAH

Retained Oxidised Faeces Aragão et al. (2004)

Protein and amino acidsAmino acid utilization

Lys Arg Glu Ala0

20

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% o

f inj

ecte

d la

belle

d A

ASole post-larvae

32 DAH

Retained Oxidised Faeces

11%

87%

65%

82%

15%

33%

41%

56%

Rønnestad et al. (2001)

Protein and amino acidsAmino acid utilization

0 1 2 3 4 5 6 7 8

FAA incl. 35S-met

0

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Rad

ioac

tivity

con

tent

in e

ach

com

partm

ent (

%)

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14C - methylated Protein

Fish

Water

Fish

Water

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Carcass

LiverGutGutLiver

Carcass

Rønnestad et al. (2000)

• Sole post-larvae use DAA preferentially to IAA for energy production

• A balanced dietary IAA profile may improve IAA retention.

• Protein hydrolysates are probably more available to sole post-larvae than intact proteins

• Supplementation of diets with AA in deficiency should consider that the absorption of free AA is faster than intact proteins

Protein and amino acids

• Sole larvae appear to have a good digestive capacity from the onset of exogenous feeding

• Sole have a good capacity to spare essential nutrients such as DHA and indispensable AA.

• Sole larvae may face difficulties in digesting diets with high levels of dietary neutral lipid and/or complex proteins

• A balanced dietary AA composition may improve growth and nitrogen utilization in sole larvae

Conclusions

Collaborations on sole research at CCMARIvar Rønnestad, H.J. Fyhn

Dep. Biology, University of Bergen, Norway

Pedro PousãoCRIP-SUL IPIMAR, Olhão, Portugal

Manuel Yúfera, Carmen SarasqueteICMAN-CSIC, Cadiz, Spain

J. Zambonino-Infante, Chantal CahuINRA-IFREMER, Brest, France

W. KovenNCM, Eilat, Israel

ThankThank YouYou!!