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Small Ruminant Research, 3 (1990) 9-18 9 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands Growth Rate, Feed Intake and Feed Utilization of Small East African Goats Supplemented with Leucaena leucocephala L.A. MTENGA and R.A. SHOO Department of Animal Science and Production, Faculty of Agriculture, Sokoine University of Agriculture, P.O. Box 3004, Chuo Kikuu, Morogoro (Tanzania) (Accepted 17 October 1988 ) ABSTRACT Mtenga, L.A. and Shoo, R.A., 1990. Growth rate, feed intake and feed utilization of small East African goats supplemented with Leucaena leucocephala. Small Rumin. Res., 3: 9-18. Growth and digestibility studies with grazing indigenous Tanzanian goats used different levels of Leucaena leucocephala. Four treatments were hay only (H), hay and 100 g leucaena (HL1), hay and 200 g leucaena (HL2) and hay plus leucaena ad libitum (HL3) in the growth study; and hay only (H), hay and 100 g leucaena (HL1), hay and 200 g leucaena (HL2) and leucaena only (L) in the digestibility study. Supplemented goats had higher growth rates (P < 0.001 ). Daily gains were 20, 23, 29 and 30 g for animals on treatments H, HL1, HL2 and HLa, respectively. Leucaena leucocephala supplementation increased total dry matter intake from 42.3 g/kg W °v5 in the control group (H) to 77.9 g/kg W °'v5 in HL8 (P<0.001). Crude protein digestibility increased with higher levels of leucaena in the diet (P< 0.001 ). Ap- parent digestibility of crude fibre was depressed with increased leucaena supplementation. Diges- tibility coefficients for treatments H, HL~, HL2 and L were 23.1, 55.2, 55.1 and 62.3 in trial 1 and 35.2, 49.3, 58.9 and 62.0 in trial 2 for crude protein; and 61.4, 60.9, 55.9 and 54.7 in trial 1 and 69.5, 59.1, 62.9 and 40.3 in trial 2 for crude fibre, respectively. Water intake and daily nitrogen retention increased with leucaena levels. Supplemented goats in HL1, HL2 and L retained 1.8, 3.5 and 9.6 g/day nitrogen compared to goats in H which were in negative nitrogen balance. INTRODUCTION There are over 6 million goats in Tanzania. They are normally kept with cattle under extensive management systems. They depend exclusively on nat- ural herbage growing on the range for their nutrient requirements. The natural grasslands are deficient in protein for most of the year and do not meet main- tenance and production requirements for small ruminants. Several workers in Tanzania have suggested the use of protein concentrate to supplement existing pasture, especially in the dry season (Kitaly, 1982). It 0921-4488/90/$03.50 © 1990 Elsevier Science Publishers B.V.

Growth rate, feed intake and feed utilization of small East African goats supplemented with Leucaena leucocephala

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Small Ruminant Research, 3 (1990) 9-18 9 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands

Growth Rate, Feed Intake and Feed Utilization of Small East African Goats Supplemented with Leucaena leucocephala

L.A. MTENGA and R.A. SHOO

Department of Animal Science and Production, Faculty of Agriculture, Sokoine University of Agriculture, P.O. Box 3004, Chuo Kikuu, Morogoro (Tanzania)

(Accepted 17 October 1988 )

ABSTRACT

Mtenga, L.A. and Shoo, R.A., 1990. Growth rate, feed intake and feed utilization of small East African goats supplemented with Leucaena leucocephala. Small Rumin. Res., 3: 9-18.

Growth and digestibility studies with grazing indigenous Tanzanian goats used different levels of Leucaena leucocephala. Four treatments were hay only (H), hay and 100 g leucaena (HL1), hay and 200 g leucaena (HL2) and hay plus leucaena ad libitum (HL3) in the growth study; and hay only (H), hay and 100 g leucaena (HL1), hay and 200 g leucaena (HL2) and leucaena only (L) in the digestibility study. Supplemented goats had higher growth rates (P < 0.001 ). Daily gains were 20, 23, 29 and 30 g for animals on treatments H, HL1, HL2 and HLa, respectively. Leucaena leucocephala supplementation increased total dry matter intake from 42.3 g/kg W °v5 in the control group (H) to 77.9 g/kg W °'v5 in HL8 (P<0.001).

Crude protein digestibility increased with higher levels of leucaena in the diet (P< 0.001 ). Ap- parent digestibility of crude fibre was depressed with increased leucaena supplementation. Diges- tibility coefficients for treatments H, HL~, HL2 and L were 23.1, 55.2, 55.1 and 62.3 in trial 1 and 35.2, 49.3, 58.9 and 62.0 in trial 2 for crude protein; and 61.4, 60.9, 55.9 and 54.7 in trial 1 and 69.5, 59.1, 62.9 and 40.3 in trial 2 for crude fibre, respectively. Water intake and daily nitrogen retention increased with leucaena levels. Supplemented goats in HL1, HL2 and L retained 1.8, 3.5 and 9.6 g/day nitrogen compared to goats in H which were in negative nitrogen balance.

INTRODUCTION

There are over 6 million goats in Tanzania. They are normally kept with cattle under extensive management systems. They depend exclusively on nat- ural herbage growing on the range for their nutrient requirements. The natural grasslands are deficient in protein for most of the year and do not meet main- tenance and production requirements for small ruminants.

Several workers in Tanzania have suggested the use of protein concentrate to supplement existing pasture, especially in the dry season (Kitaly, 1982). It

0921-4488/90/$03.50 © 1990 Elsevier Science Publishers B.V.

I0 L.A. MTENGA AND R.A. SHOO

is unlikely that peasants will respond to this recommendation because concen- trates are expensive and not easily available where the majority of goats and sheep are kept. There is therefore a need to look for cheaper alternative sources of protein. The leguminous plant Leucaena leucocephala could offer better prospects of acceptance by farmers and can supply protein needs of grazing sheep and goats (Jones, 1979; Uter Meulen et al., 1979). This study was to investigate responses of grazing goats fed low quality hay (Chloris gayana) and supplemented with different levels of Leucaena leucocephala. A similar study was started with sheep.

MATERIALS AND METHODS

Growth study Twenty-four Tanzanian indigenous goats of the small East African type were

used in an experiment to test effects of feeding Leucaena leucocephala on growth performance. Animals were divided into equal numbers of females and cas- trated males. All animals were 6-7 months of age. Initial liveweight ranged from 9.2 to 16.0 kg (mean = 12.6 kg ). All animals were grazed on the University Farm (longitude 37°39'E and latitude 6°51'5) from 08.00 a.m. to 01.00 p.m. and were supplemented with hay ad libitum. Animals were randomly allocated to four treatments. In treatment H, animals were not given leucaena while in treatments HL1, HL2 and HLa animals were offered 100 g, 200 g and ad libitum sun-dried leucaena leaves, respectively. Animals were fed in pairs consisting of a castrate and a female. Thus there were three replications per treatment. Hay (Chloris gayana) and leucaena were offered after grazing.

All animals were dewormed with Panacur (Fenbendazole, Hoechst) 14 days before the experiment and thereafter at monthly intervals. They were also subject to routine controls against external parasites. Common salt was offered to all animals and water was available all the time in the pens.

The experiment lasted 90 days. During this period, hay and leucaena intake was recorded. No attempt was made to estimate the amount of pasture con- sumed during grazing. Animals were weighed weekly. Samples of pastures grazed, hay and leucaena were collected by hand picking for chemical analysis.

Digestibility study Twelve castrated male goats from the previous study were used in the diges-

tibility experiment consisting of two trials. Goats had mean liveweight of 14.93 + 1.59 kg and 14.48 + 1.75 kg during the first and second trials. A com- pletely randomized design was used and in each trial the animals were allocated to four treatments: Rhodesgrass (Chloris gayana ) hay ad libitum (H), hay and 100 g leucaena (HL1), hay and 200 g leucaena (HL2) and leucaena only fed ad libitum (L).

Animals were drenched using Panacur 14 days before starting the experi-

GROWTH AND FEED UTILIZATION OF TANZANIAN GOATS GIVEN LEUCAENA LEUCOCEPHALA 11

ment. They were also given injections of a vitamin mixture consisting of vita- mins A, D and E (1 ml contained 50 000 I.U. vitamin A, 25 000 I.U. vitamin Dz and 20 mg vitamin E). Common salt (5 g/animal per day) and water ad libitum were provided to animals. All animals were individually penned in me- tabolism crates.

In both trials there was a 10-day preliminary period followed by a 7-day collection period. During the collection period, daily intakes of hay, leucaena and water were measured. Faecal and urine outputs in kg were also recorded. Samples of hay, leucaena, faeces and urine were collected for chemical analysis. Faeces and urine were preserved according to Schneider and Flatt (1975). Chemical components of all samples were analysed on a dry matter basis using standard methods of AOAC (1975).

There were no serious disease problems in the animals during the study. There were, however, mild cases of diarrhoea in the eighth and ninth weeks of the growth study. All animals were treated with sulphurmidine injectable so- lution and they showed no further symptoms of diarrhoea.

Statistical analyses. Growth and digestibility studies were subjected to analysis of variance (Steel

and Torrie, 1980). Duncan's New Multiple Range Test was used to test differ- ences between means.

RESULTS

Chemical composition of Chloris gayana hay, sun-dried leucaena and pasture used in the growth and digestibility studies are shown in Tables 1 and 2. Hay was of low nutritive value as shown by the low crude protein and high crude

T A B L E 1

Composition of Chloris gayana hay, Leucaena leucocephala and pasture fed to goats for growth {means ± standard deviation)

Hay L. leucocephala Pasture

Number of samples 8 8 10 Dry matter (g/kg ADW 1 ) 917.6 ± 80.4 896.6 _+ 15.6 936.7 ± 75.0 Composition o f D M (g/kg)

Crude protein 52.2 _+ 17.8 230.0__+ 20.5 142.7 ± 18.5 Crude fibre 386.5 +__ 22.7 151.8 _+ 11.5 248.3 ± 15.6 Ether extract 15.5 + 1.7 45.0__+ 5.8 27.0 ± 4.3 Ash 96.9 ± 12.3 89.2 + 6.7 85.0_+ 7.5 Nitrogen-free extract 443.9 + 48.2 484.0 ± 25.1 497.0 ± 30.3 Organic matter 903.1 _+ 75.6 910.8 _+ 30.5 915.0 _+ 45.9

~ADW = air-dry weight.

12 L.A. MTENGA AND R.A. SHOO

TABLE 2

Composition of Chloris gayana hay and Leucaena leucocephala fed to goats in the digestibility study (means +- standard deviation)

Trial 1 Trial 2

Hay Leucaena Hay Leucaena

Number of samples 8 8 8 8 Dry matter (g/kg ADW 1 ) 939.6 _+ 103.6 946.9 +- 27.5 946.1 +_ 94.8 821.4 + 28.0 Composition o f D M (g/kg)

Crude protein 44.6+ 2.9 247.8 + _ 4.9 39.4+- 1.8 269.7+- 4.0 Crudefibre 372.6+- 8.1 174.9+-16.1 411.5+- 14.1 149.4+- 6.6 Ash 81.5+- 3.6 87.7+- 8.0 105.1+- 4.0 93.0+- 5.0 Ether extract 16.4 +_ 1.5 41.7 +- 0.2 14.7 +- 1.0 42.5 +- 0.7 Nitrogen-freeextract 424.5+-123.7 394.8+_ 2.4 375.4+_104.5 266.8+- 3.6 Organic matter 858.1 +- 51.0 859.2 +- 51.3 841.0 +_ 56.0 728.4 +- 33.0

~ADW = air-dry weight.

TABLE 3

Effects of level of Leucaena leucocephala supplementation on feed intake and growth performance of Tanzanian indigenous goats during the growth study I

Trea tments

H HL1 HL2 HL3 s.e.d. 2

Number of animals 6 6 6 6 Initial liveweight (kg) 12.10 13.23 12.87 12.37 1.20 Ns Final liveweight (kg) 13.93 15.33 15.47 15.07 1.26 Ns Total weight gain (kg) 1.83 a 2.10 ~ 2.60 b 2.70 b 0.25** Growth rate (g/day) 20 a 23 ~ 29 ab 30 b 2.8** Dry matter intake (g/day)

Hay 108.2 a 89.4 b 95.1 b 82.2 ¢ 2.98*** Leucaena 69.1 a 120.6 b 116.7 b 15.69" Total intake of supplements 108.2 ~ 158.5 b 215.6 ¢ 198.8 c 14.88"**

Organic matter intake g/day 97.7 a 143.7 b 195.7 c 180.5 c 13.56"** g/kg W °'75 14.4 ~ 19.9 b 27.2 c 26.0 ~ 2.51"**

Crude protein intake g/day 6.2 ~ 21.0 b 29.2 c 31.5 ¢ 3.55*** g/kg W °'75 0.9 ~ 2.9 b 4.6 ¢ 4.6 ¢ 0.53***

IThere was no statistical evidence of sex and treatment interaction on growth rate, so the data for sex were pooled. For feed intake, values are averages for each pair consisting of a male and a female and the pair was treated as an experimental unit. 2In this and subsequent tables, means within the same row bearing different superscripts are different: *P < 0.05, **P < 0.01, ***P < 0.001 and Ns (not significant) P > 0.05.

GROWTH AND FEED UTILIZATION OF TANZANIAN GOATS GIVEN LEUCAENA LEUCOCEPHALA 13

TABLE 4

Effects of Leucaena leucocephala supplementation of Tanzanian indigenous goats on nutrient intake and apparent digestion coefficients in the digestibility study

Treatments

H HL, HL2 L s.e.d.

Trial 1 Daily intake

Dry matter (g) 319 386 415 584 87.3 Ns Dry matter (g/kg W °'v~) 43.20 a 49.83 a 53.90 b 77.13 b 9.4* Crude protein (g) 14 ~ 36 ~ 57 ~b 144 c 18.5"** Crude protein (g/kg W °vS) 1.93 ~ 4.73 a 7.43 ~b 19.10 c 21.97"** Organic matter (g) 293 354 380 533 79.8 Ns

Digestibility coefficients ( % ) Dry matter 55.0 56.7 55.5 66.1 4.52 Ns Crude protein 23.1 ~ 55.2 b 55.1 b 62.3 b 7.08** Crude fibre 61.4 60.9 55.9 54.7 8.74 Ns Organic matter 56.8 58.4 56.7 66.6 4.45 Ns DOMD 52.1 53.5 51.9 60.8 4.08 Ns

Digestibility concentrations Digestible energy' ( M J / k g DM ) 9.9 10.2 9.9 11.6 - Metabolizable energy 2 (MJ) 7.8 8.0 7.8 9.1 -

Trial 2 Daily intake

Dry matter (g) 354 318 438 516 99.9 Ns Dry matter (g/kg W °'vS) 58.43 a 41.80 a 58.80 ~ 67.80 ac 6.73* Crude protein (g) 14 ~ 31 ~ 55 ab 139 ¢ 16.1"** Crude protein (g/kg W0.75) 1.93 ~ 4.20 a 7.47 b 18.30 ¢ 1.35"** Organic matter (g) 317 286 394 468 89.8 s s

Digestibility coefficients (%) Dry matter 55.9 50.7 57.9 57.6 8.01Ns Crude protein 35.2 ~ 49.3 b 58.9 b 62.0 ~ 4.23*** Crude fibre 69.6 ~ 59.1 a 62.9 ~ 40.3 b 5.94 Ns Organic matter 57.3 51.8 58.8 58.5 7.77 Ns DOMD 51.3 46.5 52.9 53.1 6.95 Ns

Digestibility concentrations Digestible energy 1 ( M J / k g DM) 9.7 8.8 10.0 10.0 Metabolizable energy 2 (M J ) 7.7 7.0 7.9 8.0

1DE=0.19 DOMD To and ~ME=0.15 DOMD (MAFF, 1975).

f i b r e c o n t e n t . L e u c a e n a u s e d i n t h e g r o w t h e x p e r i m e n t w a s o b t a i n e d f r o m m a -

t u r e p l a n t s w h i l e t h a t f e d t o g o a t s i n t h e d i g e s t i b i l i t y s t u d y w a s c u t f r o m re -

g r o w t h , h e n c e d i f f e r e n c e s i n p r o t e i n c o n t e n t .

Growth s tudy L e u c a e n a s u p p l e m e n t a t i o n h a d a s i g n i f i c a n t e f f e c t o n d a i l y g a i n s . S u p p l e -

m e n t e d g o a t s i n t r e a t m e n t s H L 1 , H L 2 a n d H L 3 g a i n e d 3, 9 a n d 10 g / d a y m o r e

14 L.A. MTENGA AND R.A. SHOO

than animals in treatment H. Growth rates of 30 g/day observed in treatment HL3 were higher than those in treatments H and HL1 ( P < 0.05) but not dif- ferent from those in treatment HL2. There was a tendency for growth rate to increase with higher leucaena levels.

Table 3 shows that hay intake for goats in treatment HL3 was reduced ( P < 0.05). When total intake of supplements was expressed as g/kg W °Ts, intake increased with levels of leucaena although there was a slight depression of intake in treatment HL3. Organic matter intake and nitrogen intake also increased with increasing level of sun-dried leucaena on offer.

Unfortunately, dry matter intake from grazing was not measured in this

T A B L E 5

Effects of Leucaena leucocephala s u p p l e m e n t a t i o n of T a n z a n i a n i n d i g e n o u s goa ts on nitrogen utilization in the digestibility study

Treatments

H HL1 HL2 L s.e.d.

Trial 1

N i t r o g e n i n t a k e

g / d a y 2.28 ~ 5.83 ~

g / k g W °'75 pe r day 0.31 ~ 0.76

N i t r o g e n e x c r e t i o n ( g / d a y )

Faecal 2 a 3 ~

U r i n a r y 1 2

Total 3 ~ 5 ~

N i t r o g e n retention g / d a y - 0.74 1.3 ~

g / k g W °'v5 pe r day - 0 . 0 9 4 0.16 ~

as percent of nitrogen i n t a k e - 29.84 22.1 b

as percent of nitrogen d i g e s t e d - 60.4" 39.9 b

Trial 2

N i t r o g e n i n t a k e

g / d a y 2.2 ~ 5.0 a g / k g W O'75 pe r day 0.31 ~ 0.67 ~

N i t r o g e n e x c r e t i o n ( g / d a y )

Faeca l 1.6 ~ 2.6 ~

U r i n a r y 1.6 a 1.8 a

T o t a l 3.2 ~ 4.3 a

N i t r o g e n retention g / d a y 1.0 ~ 0.7 ~ g / k g W °-75 pe r da y - 0 . 1 4 a 0.09 ~

as percent of nitrogen i n t a k e - 4 3 . 5 ~ 14.3 b

as percent of nitrogen d i g e s t e d - 90.7 ~ 29.0 b

9.12 ab 23.17 ¢ 2.96***

1.19 ab 3.06 ¢ 0.32***

4 b 9 ¢ 0.8***

2 5 0.6*** 6 ab 15 ¢ 1.1"**

2.84 9.6 b 2.21"*

0.37 a 1.26 b 0.27***

30.9 b 41.5 b 10.34"**

56.3 b 65.5 b 100.37'**

8.8 b 22.3 ¢ 2.57***

1.20 b 2.92 ¢ 0.22***

3.6 ab 8.8 c 0.73***

2.6 a 5.9 ¢ 0.65*** 6.2 ab 14.3 c 1.32"**

2.6 ab 8.0 c 1.48"**

0.35 ab 1.05 ¢ 0.16"**

29.2 ~ 36.0 ~b¢ 20.77**

49.7 ab 57.54h¢ 85.30***

GROWTH AND FEED UTILIZATION OF TANZANIAN GOATS GIVEN LEUCAENA LEUCOCEPHALA 15

study. Crude protein and organic matter intake in the growth and digestibility studies tended to increase with leucaena levels.

Digestibility study Apparent digestibility coefficients under the influence of leucaena supple-

mentation are shown in Table 4. Crude protein intake (g/day and g/kg W °'75) increased with leucaena levels in the diet ( P < 0.05).

Leucaena inclusion did not have a significant influence on dry matter diges- tibility. Differences between H and other treatments in crude protein digesti- bility were highly significant (Table 4) in both trials. It was surprising that crude fibre digestibility decreased with increased levels of leucaena supple- mentation in both trials although differences between treatments were not significant. Organic matter digestibility was not significantly affected by treat- ment but was highest in treatment HL1 in both trials. Goats fed leucaena only ad libitum (treatment L) remained healthy throughout the experiment.

Nitrogen utilization data for both trials in the digestibility study are shown in Table 5. In both trials, leucaena supplementation had a highly significant (P < 0.001 ) effect on nitrogen utilization by goats. N intake (g/day and g/kg W o.Ts ) increased with increasing leucaena levels in the diet. Faecal and urinary nitrogen increased with leucaena levels. Nitrogen retention was negative for unsupplemented goats but positive for those on leucaena. Highest nitrogen retention in both trials was in treatment L. Data on nitrogen utilization were

T A B L E 6

Water intake by goats as influenced by Leucaena leucocephala supplementation in the digestibil- ity study

Treatments s.e.d.

H HL1 HL2 L

Trial 1

Water i n t a k e

kg/day 0.54 a 0.58 °

% l i v e w e i g h t 3.8 a 3.8"

k g / k g dry matter i n t a k e 1.70 1.49

Ash intake (g/day) 26" 32"

0.67 a 1.11 b 0.11"*

4.4 a 7.6 b 0.62***

1.61 1.98 0.19 Ns

35 a 51 b 7.5*

Trial 2

Water i n t a k e

kg/day 0.48 a 0.51 a 0.67 a 1.12 b 0.14"*

% l i vewe igh t 3.4 a 3.5 a 4.7 a 7.5 b 0.64***

k g / k g dry matter intake 1.41 a 1.66 ° 1.55 a 2.18 b 0.22*

Ash intake (g/day) 37 32 44 48 10.08 Ns

16 L.A. MTENGA AND R.A. SHOO

analysed for information on nitrogen requirements for maintenance. The regression was:

Y = 0.697X- 0.249 (residual s.d. = 0.126, r 2 = 0.95 )

where X is true digestible nitrogen and Y is nitrogen retention. This gives a daily maintenance requirement for goats of 0.357 g N/kg W °75. A factorial method (Reynolds, 1981) was also used to obtain nitrogen requirement for maintenance as: 0.463 g N/kg W °75.

Table 6 shows mean t reatment effects on water intake in the digestibility study. There was a tendency for water intake (expressed as g/day, and % of liveweight) to increase with increasing levels of leucaena in the diet; the high- est significant value was recorded for goats in t reatment L. When intake was expressed as g/kg dry matter intake, differences between treatment L and other treatments were reduced and were non significant in trial 1.

DISCUSSION

Crude protein content of sun-dried leucaena was 230 +_ 20.5 g/kg DM and within the range reported by other workers, ranging from 210 (Upadhyay et al., 1974) to 340 g/kg DM (Uter Meulen et al., 1979). Dried leucaena was used in this study because of uniformity in quality compared to fresh leucaena whose chemical composition is likely to change with weather changes (Jones, 1979). Chloris gayana hay used in this experiment was low of quality and its crude protein most likely did not meet requirements for nitrogen (Kitaly et al., 1985). Pastures grazed had a crude protein value of 143 + 18 g/kg DM, which is higher than 88 +_ 6 reported by Nyakyi (1981) from the same area. This is likely due to time differences in sampling.

Leucaena supplementation tended in general to reduce voluntary hay con- sumption. Supplemented animals (treatments HLI, HL2 and HL3) had high daily dry matter intake of supplements compared with unsupplemented ani- mals, similar to reports by Adeneye and Oyenuga (1976) and Massae (1984). Growth rate of goats increased with levels of leucaena probably because of increased intake of protein, similar to the report by Rukanda and Lwoga (1981) with sheep. Growth of 20 g/kg for goats in the control treatment H was similar to previous studies (Nyakyi, 1981; Massae, 1984; Kitaly et al., 1985).

Total intakes of supplements were influenced by pasture consumed during grazing as these values are very low (108 to 216 g DM/day). The amount of dry matter consumed from pastures was not measured. Values obtained in the digestibility study when goats did not graze (Table 4) ranged from 319 (43.3 g/kg W °7~) to 584 (77.9 g/kg W °75) g DM/day equivalent to 2.2 to 4.0% of body weight, similar to findings of Devendra and Burns (1970).

Digestibility coefficients for dry matter in t reatment L (leucaena only) ranged from 58 to 68%, while the digestibility coefficient for crude protein was 62%. These values are similar to 51.3% and 61.9% for dry matter and crude protein, respectively, reported by Wahyuni et al. (1982). Nitrogen mainte-

GROWTH AND FEED UTILIZATION OF TANZANIAN GOATS GIVEN LEUCAENA LEUCOCEPHALA 17

nance requirements obtained in this study were similar to those of Reynolds (1981) with goats in Malawi.

With the exception of crude fibre, highest digestibility coefficients for other nutrients were observed in treatment L for leucaena only ad libitum. Wahyuni et al. (1982) had similar findings on Ongole bulls fed leucaena only ad libitum. Depression in crude fibre digestibility with increased dietary protein has also been reported by Adeneye and Oyenuga (1976) and Kitaly (1982). Increased protein intake is often associated with high dry matter intake, resulting in faster rates of passage of digesta through the gastro-intestinal tract. The time feed is exposed to digestive enzymes and the action of tureen microbes is shorter and this may result in low crude fibre digestibility (Van Soest, 1982).

Unsupplemented goats were in negative nitrogen balance, indicating that hay in the present study could not meet maintenance nitrogen requirements. Thus, protein supplementation of such low quality roughages is needed, as suggested by Reynolds (1981) and Kitaly (1982).

Water intake increased with levels of leucaena in the diet and was highest in treatment L. Massae (1984) reported that water requirements of growing ruminants depend on rate of growth, weight of animal and type of feed. Dry matter and ash content of a feed may also affect water needs of ruminants, which may have contributed to the increased water intake with increasing leu- caena supplementation in this study.

It can be concluded the sun-dried Leucaena leucocephala supplementation increased growth rate and feed utilization of indigenous Tanzanian goats. Un- der practical field conditions, farmers might be inclined to allow goats to browse leucaena rather than cut and feed it. Different responses in growth perform- ance could therefore be obtained if grazing goats are allowed to browse green leucaena shrubs. It would be interesting to verify this. Further studies are needed to determine optimum levels of leucaena in goat diets and the effect of leucaena concentrate mixture on feed utilization, growth rate, carcass composition, milk yield and composition of goats and other ruminant species.

REFERENCES

Adeneye, J.A. and Oyenuga, V.A., 1976. Energy and protein requirements of West African Dwarf sheep. I. Effect of feeding four levels of dietary energy to sheep. E. Aft. Agric. J., 42: 89-97.

AOAC, 1975. Official Methods of Analysis, 12th edn. Association of Official Agricultural Chem- ists, Washington, DC.

Devendra, C. and Burns, M., 1970. Goat Production in the Tropics. Tech. Commun. No. 19, Commonwealth Agricultural Bureaux, Farnham Royal, Great Britain, 182 pp.

Jones, R.J., 1979. The value ofLeucaena leucocephala as a feed for ruminants in the tropics. World Anita. Rev., 31: 13-23.

18 L.A. MTENGA AND R.A. SHOO

Kitaly, A.J., 1982. Effect of supplementing low quality hay with different levels of protein on growth performance of goats. M.Sc. Thesis, University of Dares Salaam, Tanzania, 157 pp.

Kitaly, A.J., Mtenga, L.A. and Goodchild, A.V., 1985. Feed utilization in Tanzania goats fed Chloris gayana hay with supplements containing different protein levels. Tanzania Soc. Anita. Prod., 10: 284-305.

MAFF, 1975. Energy allowances and composition of feeding stuff for ruminants. Tech. Bull. 33, Ministry of Agriculture, Fisheries and Food. HMSO, London.

Massae, E.E., 1984. A study on compensatory growth in Tanzania sheep. M.Sc. Thesis, University of Dares Salaam, Tanzania, 205 pp.

Nyakyi, F.P., 1981. Meat production from sheep. The effect of breed and concentrate supplemen- tation on the growth performance and carcass composition. M.Sc. Thesis, University of Dar es Salaam, Tanzania, 236 pp.

Reynolds, L., 1981. Nitrogen metabolism in indigenous Malawi goats. J. Agric. Sci., 96: 347-351. Rukanda, N.A.K. and Lwoga, A.B., 1981. The role of legumes in improving natural grasslands for

livestock production in Africa. In: J.A. Kategile, A.N. Said and F. Sundstel (Editors), Utili- zation of Low Quality Roughages in Africa. AUN, Agricultural Development Report, Aas, Nor- way, pp. 185-188.

Schneider, B.H. and Flatt, W.P., 1975. The Evaluation of Feeds through Digestibility Experi- ments. University of Georgia Press, Athens, GA, 423 pp.

Steel, R.G.D. and Torrie, J.H., 1980. Principles and Procedure of Statistics, 2nd edn. McGraw- Hill, New York, NY, 389 pp.

Upadhyay, V.S., Reikb, A. and Pathak, P.S., 1974. Nutritive value of Leucaena leucocephala (Lain.) de Wit. Indian Vet. J., 51: 543-537.

Uter Meulen, P., Struck, S., Schulke, E. and El Harith, E.A., 1979. A review on the nutritive value and toxic aspects ofLeucaena leucocephala. Trop. Anita. Prod., 4: 113-126.

Van Soest, P.J., 1982. Nutritional Ecology of the Ruminant. Cornell University Press, Ithaca, NY, 373 pp.

Wahyuni, S., Yulisanti, E.S., Komara, W., Yates, N.G., Obst, J.M. and Lowry, J.B., 1982. The performance of Ongole cattle offered either grass, sun-dried leucaena or varying proportions of each. Trop. Anita. Prod., 7: 257-282.