Performance of growing goats fed Gliricidia maculata

Small Ruminant Research 39 (2001) 113±119

Performance of growing goats fed Gliricidia maculata Nguyen van Haoa,b,*, Inger Ledinb a

b

Department of Animal Nutrition, University of Agriculture and Forestry, Thu Duc, Ho Chi Minh City, Viet Nam Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Box 7024, 750 07 Uppsala, Sweden Accepted 29 May 2000

Abstract Sixteen female crossbred (local  Anglo-Nubian) goats raised from 20±30 kg were fed a basal diet of cassava chips, cotton seed cake, rice bran and rice straw, where 0, 30, 40 or 50% of the diet dry matter was replaced with leaves from Gliricidia maculata. All the diets containing Gliricidia resulted in a higher intake than the diet without Gliricidia, but the diet with 30% Gliricidia gave the best intake and the highest growth rate, 105 g per day. Total intake was 2.8% of the body weight (BW). Five male goats of the same breed and size were used to study the effect of supplementing rice straw with different levels of Gliricidia leaves on intake and apparent digestibility of the diets. Increasing the amount of Gliricidia leaves decreased the rice straw intake but increased intake of total dry matter (DM), organic matter (OM), neutral detergent ®bre (NDF), acid detergent ®bre (ADF) and crude protein (CP). Supplementing with Gliricidia leaves improved the dry matter digestibility (DMD), the OM digestibility and the CP digestibility in the mixed Gliricidia and rice straw diet, compared to pure rice straw, but the values were somewhat lower than could be expected by calculations from the pure rice straw and Gliricidia diets. The DMD of Gliricidia was 64.1%. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Goats; Cassava; Rice straw; Gliricidia; Growth; Intake; Digestibility

1. Introduction In the tropical wet zone of south east Asia, most of the arable land has been utilised for high value food crops and industrial crop production (Chen et al., 1991). The ruminant livestock production in these areas plays a complementary role in utilising the by-products of crops and getting some income from land unsuited to crop production. The ®brous crop byproducts are the major potential feed resources, and the by-products from rice are most abundant, followed by those from cassava, maize, cotton seed and banana. However, the ®brous crop by-products are characterised by extensive ligni®cation of the cellulose * Corresponding author. Fax: ‡46-18-672996. E-mail address: [email protected] (N. van Hao).

and the hemicellulose, and by low levels of protein, soluble carbohydrates and minerals. As a consequence, the intake and digestibility of these feeds are not suf®cient to sustain satisfactory levels of production. Supplementation with protein, but also with soluble carbohydrates, is very important for obtaining a good production (Chen et al., 1991). The leaves from leguminous trees and shrubs are cheap and readily available sources of protein. One of the possible species that can be used is Gliricidia maculata. Ella (1988) reported that the annual dry matter (DM) leaf yield of Gliricidia was around 23 t/ha. The chemical composition and nutritive value of Gliricidia place it among the high quality forages from tropical areas. NFTA (1987) reported that the evaluations of Gliricidia as an animal feed for beef and dairy cattle, sheep and goats have shown promising results.

0921-4488/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 0 0 ) 0 0 1 7 7 - 2

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The range of nutritive values found, as percent of DM were according to NFTA (1987) dry matter digestibility (DMD) 48±77%, crude protein (CP) 18±30%, acid detergent ®bre (ADF) 18±34%, neutral detergent ®bre (NDF) 27±50%, crude ®bre (CF) 13±30%, ether extract 4±8%, ash 6±10% and calcium 1±2%. The utilisation of Gliricidia as a fodder for farm animals has been tested in Central America, Africa and Asia (Devendra, 1990) and according to Wiersum and Nitis (1992) and Stewart and Simons (1994) Gliricidia has the potential to become a major source of feed for goats and cattle in dry land farming areas. The objectives of the present experiment were to evaluate the effect of feeding different levels of Gliricidia leaves as a protein source in diets based on locally available crop by-products on the growth of goats and to see if the digestibility of rice straw could be improved by supplementation with Gliricidia. 2. Materials and methods 2.1. Location and climate of the study area The experiment was conducted at the experimental farm of the National University in Ho Chi Minh City. The climate in the area is tropical monsoon, with a dry season between November and April and a wet season from May to October with an average of 1600 mm rainfall. The mean annual temperature is 288C. The experiment was conducted between April and June 1998, a year when the wet season started very late (June). 2.2. Experimental animals and feeds The animals were selected from a ¯ock of goats raised in a con®nement system. For the growth experiment 16 females, 6 months old (local female  AngloNubian male; mature weight 35 kg) were selected. In the digestibility study, 5 male 8 months old goats were used. All goats weighed between 19 and 21 kg, when the experiments started. The goats were vaccinated against foot and mouth disease and treated against gastrointestinal parasites using Albendazole tablets before the commencement of the experiment. Rice straw was harvested at the university farm and baled in February and March, 1998. The rice straw

was chopped (10±15 cm) before feeding. Fresh leaves of Gliricidia maculata, from shrubs planted in 1992 at the university farm, were harvested every day at 6 a.m. for the growth experiment. The leaves and small twigs were included in the feed. Cassava chips, rice bran and cottonseed cake were bought from local feed mills. 2.3. Experimental design The diets in the growth experiment (90 days) were calculated using table values for energy (NIAH, 1995) and a preliminary chemical analysis of the experimental feeds. The animals were fed DM at a level of 3% of their body weight (BW) and energy and protein to meet the requirements for maintenance and 100 g of growth per day according to Peacock (1996). The goats were randomly assigned to four treatments of four animals. The Gliricidia contents were 0 (control), 30, 40 or 50% of the offered DM. The intention was to feed the same amount of DM with the same content of energy and digestible CP in all diets. Since the Gliricidia contained around 25% of CP in DM this meant that the protein sources used could be decreased when the level of Gliricidia in the DM increased. The actual amounts and feeds offered are shown in Table 2. In the digestibility experiment the animals were allocated to ®ve dietary treatments with different levels of Gliricidia according to a Latin Square arrangement (5  5) (Mead et al., 1986) (Table 3). The digestibility experiment lasted 17 weeks in total, 2 weeks of adaptation and ®ve periods consisting of 3 weeks per period (1 week of adaptation, 1 week of collection and 1 week for releasing the animals on an open ground for exercise). During the period of exercise the animals were fed on the experimental feed stuffs supplemented with rice bran and cotton seed cake. 2.4. Feeding and management The goats in the growth experiment were individually housed and fed. In the digestibility experiment the animals were kept in simple metabolism cages, that allowed separation of faeces and urine. The feeding troughs were divided into sections, making it possible to feed each feed stuff separately. Drinking water, salt and mineral lick blocks were available at all times. The animals were fed twice per day at 08.00 and 14.00 h.

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2.5. Data collection and analyses The animals in the growth experiment were weighed when the experiment started and then once per week always at 07.00 h. The feed consumption was recorded and the feed refusals were collected from individual animals and weighed every day in the morning before feeding. Samples of feeds, rice straw, rice bran, cotton seed cake and cassava chips were taken once per week. Since it can be expected that these feed stuffs were relatively constant in their composition (the feed stuffs were bought as one lot at the same time) the samples were pooled to two samples per month. Samples of Gliricidia leaves were taken every day and pooled weekly. DM content was, however, determined daily before feeding. The refusals were collected every day and pooled together to a weekly sample. During the collection period of the digestibility experiment, samples of rice straw were taken once per week, while samples of Gliricidia leaves were taken every day and pooled weekly. DM content was, however, determined daily. Feed refusals were collected from individual animals and weighed every day. Samples of faeces and urine were collected every morning (urine into a solution with sulphuric acid), weighed and kept in a deep freeze. The animals were weighed before the commencement of the adaptation period and before feeding on the ®rst and last days of each collection period. The feeds and refusals in the growth experiment and the digestibility study were analysed for ash, organic matter (OM), nitrogen (N), NDF and ADF. Samples for the chemical analysis were taken from previously

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bulked feed, refusals and faeces and pre-dried at 608C before grinding using a 1 mm screen and a hammer mill. DM content in the samples was determined by drying to constant weight at 1058C. N was determined using the Macro Kjeldahl method (AOAC, 1985). Ash content was determined by incinerating the samples at 5008C. NDF and ADF were determined using procedures described by Goering and Van Soest (1970). 2.6. Statistical analysis The data from the experiment was statistically analysed with a variance analysis using the general linear model (GLM) of Minitab Software (Minitab, 1998). The following model was used for the growth experiment: Yi ˆ m ‡ Ai ‡ ei where Yi is the growth or feed consumption, m the overall mean, Ai the effect of diet, and ei random error. For the digestibility experiment the model below was used: Yijk ˆ m ‡ Ai ‡ Bj ‡ Ck ‡ eijk where Yijk is the dependent variable, m the overall mean, Ai the effect of diets, Bj the effect of animals, Ck the effect of periods, and eijk random error. 3. Results The chemical composition of the feeds used in the experiments is shown in Table 1. Cassava chips and rice straw had low contents of CP while Gliricidia

Table 1 Chemical composition of the diet components, means and S.E. Growth experiment

Digestibility experiment

Gliricidia leaves

Cotton seed cake

Cassava chips

Rice bran

Rice straw

Gliricidia leaves

Rice straw

Samples DM (%)

12 23.0  1.0

6 90.4  0.4

6 90.0  0.3

6 89.0  0.2

6 90.0  0.5

5 22.0  0.3

5 90.0  0.5

Percent in DM Ash OM CP ADF NDF

11.3 88.6 24.8 32.1 43.5

5.0 95.0 37.0 30.8 43.7

1.8 98.0 3.8 5.5 7.9

8.3 91.0 16.3 9.5 16.0

16.1 83.9 4.0 51.4 79.2

11.2 88.7 24.9 31.6 43.7

16.0 83.0 4.0 51.0 79.0

    

0.7 0.7 0.8 2.1 1.8

    

0.3 0.3 0.5 1.5 0.6

    

0.1 0.1 0.2 0.3 0.1

    

0.1 0.1 0.3 0.2 0.3

    

0.3 0.2 0.4 0.9 0.8

    

0.4 0.4 0.6 2.3 0.8

    

0.3 0.3 0.4 0.9 0.9

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Table 2 Growth experiment: amounts of feed offered and ingested, composition of feed intake and BW changes of the goats, means and S.E. Experimental diets GL0

GL30

GL40

GL50

Feed offered (g DM per day) Cotton seed cake Rice bran Cassava chips Rice straw Gliricidia Total

200 90 250 135 ± 675

60 ± 250 163 202 675

10 ± 250 145 270 675

± ± 225 112 338 675

Feed intake (g DM per day) Cotton seed cake Rice bran Cassava chips Rice straw Gliricidia

158a 90 250a 108a ±

   

1.5 0.8 0.0 0.5

59b  0.8 ± 250a  0.0 145b  1.0 201a  1.0

10c  0.5 ± 250a  0.0 118c  1.4 264b  0.9

± ± 225b  0.0 95d  1.0 301c  0.5

Total intake (g per day) DM OM CP ADF NDF

604a 565a 83a 125a 188a

    

2.6 2.9 0.9 1.0 0.9

658b  0.8 603b  1.0 91b  0.6 172b  1.0 249b  0.6

643c 588c 88c 165c 237c

622d 572d 86d 155d 224d

Initial weight (kg) Final weight (kg) LWG (g per day)

19.4  0.3 27.3  0.9 88.3  8.2

19.9  1.0 28.8  0.8 98.6  6.9

19.6  0.6 28.1  0.4 94.4  6.5

a,b,c,d

    

1.5 2.7 1.0 0.9 1.0

    

1.3 1.3 0.6 0.9 0.9

20.3  0.7 28.4  0.6 90.2  7.9

Different superscripts within rows indicate signi®cant differences, P < 0:05; GL: Gliricidia.

leaves, cotton seed cake and rice bran contained high amounts of CP. Gliricidia, cotton seed cake and rice straw had a high content of NDF and ADF. In the growth experiment there were signi®cant differences among the treatments in the total intake of DM, OM, CP, ADF and NDF (Table 2). Total DM intakes were higher for the diets containing Gliricidia. The total DM intake were highest on the diet containing 30% Gliricidia. There were, however, no signi®cant differences in intake as percent of BW between goats fed Gliricidia compared to those given no Gliricidia. The mean intake was 2.83% of BW. The effects of Gliricidia supply on BW changes are shown in Table 2. The mean daily gains were highest in the treatment with 30% Gliricidia, but differences were not signi®cant (P > 0:05). In the digestibility experiment (Table 3), supplementation with different levels of Gliricidia leaves to rice straw resulted in a signi®cant increase of the total intake of DM. The digestibility of DM and OM was

highest in the diet consisting of 100% Gliricidia, and Gliricidia supplementation increased (P < 0:05) apparent CP digestibility compared to the basal rice straw diet. Calculations of DM and CP digestibility for the mixed diets based on the intake and digestibility of straw and Gliricidia, respectively, showed that the expected values were somewhat higher than the values actually obtained. The age of the animals, in this analysis the effect of period, had no in¯uence on the digestibility values. All diets with Gliricidia supplementation resulted in a positive N balance, while the straw gave a negative N balance (Table 3). 4. Discussion Gliricidia has a strong, unpleasant odour and it is reported (Nitis et al., 1991) that cattle may go off feed when ®rstly introduced to a Gliricidia sepium diet,

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Table 3 Intake, apparent digestibility and nitrogen balance when feeding rice straw (RS) supplemented with Gliricidia leaves (GL) to goats, means and S.E. Experimental diets

Feed intake (g DM per day) Rice straw Gliricidia Total intake

600 g RS

420 g RS ‡ 180 g GL

360 g RS ‡ 240 g GL

300 g RS ‡ 300 g GL

600 g GL

S.E.

299.1a 0.0a 299.1a

247.6b 168.5b 416.1b

198.4c 224.7c 423.1b

187.5d 280.6d 468.1b

0.0e 507.4e 507.4c

9.1 9.6 13.4

58.2a,b 61.1a,b 63.3b

64.1b 66.3b 70.7b

1.5 1.5 4.4

12.36b 4.53b 4.79a,b 3.04a

20.32c 5.95c 7.21b 7.19b

0.5 0.2 0.6 0.9

Digestibility (%) DM OM CP

55.5 59.6 3.5a

58.4a,b 61.5a,b 58.4b

59.1a,b 62.1a,b 61.3b

Digestibility (%) calculated DM CP

59.0 58.4

60.1 62.8

60.7 64.2

Nitrogen balance (g per day) N-intake N in faeces N in urine N-balance

1.96d 1.89d 0.90c ÿ0.75a

a,b,c,d,e

8.22a 3.42a 3.38a,c 1.42a

10.21a,b 3.95a,b 3.86a 2.39a

Different superscripts within rows indicate signi®cant differences, P < 0:05.

while goats did not seem to be affected. The odour can be minimised by wilting, by harvesting the leaves in the evening and feeding to livestock the next day (Nitis et al., 1991). The goats in this experiment had been fed Gliricidia maculata earlier. The animals were adapted to eating the Gliricidia within the ®rst few days of the preliminary period and it only took 20±30 min for the animals to clear most of the feeds, except the rice straw, from the feeding troughs. The goats on all dietary treatments readily consumed the feeds, indicating no palatability problems. The goats on the diet containing no Gliricidia, however, were not able to consume all the cotton seed cake and the faeces were very dry and hard. According to Chadhokar and Kantharaju (1980) Gliricidia maculata was found to be palatable by both cattle and sheep even when fed in very large quantities over a long period. In the digestibility experiment the increasing levels of Gliricidia resulted in an increase in the total intake but a depression in intake of the basal rice straw diet. This was probably due to the substitution effect, as reported by Chadhokar and Kantharaju (1980), Ash (1990) and Kimambo et al. (1992). Leng (1987), also

reported that when roughages of low nitrogen concentration are given to ruminants, a supplementation with protein often results in an increase in voluntary feed intake, caused by increased availability of fermentable nitrogen. Supplementation of straw with Gliricidia leaves resulted in an increase in the digestibility of DM, OM, and CP in the total diet, which could be expected. These results are in agreement with those observed by Mosi and Butterworth (1985) and McMeniman et al. (1988), who reported an improvement in digestibility when sheep were fed a crop residue diet supplemented with legume straw and increasing levels of the legume Trifolium tembense (Clover). However, the increase of the digestibility of the diet seemed to be an effect of the higher level of Gliricidia and the digestibility of the straw DM was apparently not affected. The level of Gliricidia supplementation did not seem to be important for the digestibility of CP in spite of the fact that the CP intake increased signi®cantly. This could be due to the presence of large quantities of condensed tannins in the diets with high levels of Gliricidia leaves. This result agrees with the study of Jones (1979), and Reed et al.

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(1990), who reported that fodder tree leaves should constitute about 30% of the diet, because of the secondary compounds which inhibit the digestibility and reduce the acceptability to animals at higher levels of inclusion. Also Devendra (1993) and Stewart and Simons (1994) concluded that when used as supplements the optimum dietary level of fodder trees and shrubs should be about 30±50% of the ration on a DM basis. The Gliricidia leaves signi®cantly improved not only DMD and daily N intake but also N balance compared to the straw diet in the digestibility experiment. According to Crowder and Chheda (1982), low protein content in herbage results in low apparent protein digestibility, and the digestibility approaches a zero value when CP content declines to around 3%. Van Soest (1982) reported that apparent digestibility can be negative in the case where a small intake or low digestibility is associated with a relatively large metabolic loss of the constituent. All goats were however, in positive N balance on the diets containing Gliricidia, indicating that these rations can meet the N requirement of the goats. Similar results have been reported on the intake and digestibility by goats and sheep when rice straw was supplemented with Gliricidia (Richards et al., 1994; Senani et al., 1997; Srinivasulu et al., 1998). The CP content should have been enough according to the requirements for maintenance and 100 g of growth per day for all the diets (Peacock, 1996). The goats given Gliricidia had a somewhat higher daily weight gain than the goats given no Gliricidia, but the differences were not signi®cant. Since there were only four animals per treatment, the differences may have been too small to be signi®cant. In the digestibility experiment the animals fed only straw consumed about 2.2 MJ ME per day and the animals fed pure Gliricidia 5.5 MJ ME per day. This was below the energy requirements of the animals and increasing levels of Gliricidia resulted in an increased proportion of N in the urine, showing that the lack of energy lead to increased losses of degradable N via the urine. According to Van Eys et al. (1986), Nitis et al. (1991) and érskov (1992), better performance can be obtained by supplementing the diet with Gliricidia, and this may be associated with a greater supply of bypass protein from the Gliricidia leaves. This effect

was not looked into in this experiment. It may be that the effect of the tannins are optimal at some level and according to earlier mentioned authors (Jones, 1979; Reed et al., 1990; Devendra, 1993; Stewart and Simons, 1994; Devendra and D' Mello, 1995), that level seems to be around 30% of Gliricidia in the diet DM, which was also the case in this study. The use of Gliricidia or leaves from other leguminous feeds gives an opportunity to provide variety in the diet. Goats prefer to select from a variety of feeds, such as a combination of grasses, shrubs or tree leaves and are said not to thrive well when kept on a single type of feed for any length of time (Devendra and Burns, 1983). Using tree leaves as a fodder also decreases the dependency on concentrates. The actual amount of leaves fed will be a question of the relation between feed costs and production, a lower production with a higher level of leaves may give the best pro®t to the farmer. 5. Conclusions Replacing 30% of the DM in the diet with Gliricidia resulted in increased total intake of DM, OM and CP. There were no signi®cant differences in growth rate due to level of Gliricidia in the diet. DM digestibility for straw was 55.5%, and for pure Gliricidia, 64.1%. Combinations of straw and Gliricidia had intermediate digestibilities, somewhat lower than calculated values suggesting that there was no positive interaction between the straw and the Gliricidia. The results indicated that moderate levels (30±40% of diet DM) of Gliricidia can be used in diets for growing goats without any negative effects on intake and performance. Acknowledgements The authors would like to acknowledge the Swedish International Development Authority (SIDA) which sponsored this study. We also thank the Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, Uppsala and members of the staff of the Animal Nutrition Department of the University of Agriculture and Forestry, Ho Chi Minh City.

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