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Performance of young west African Dwart goats and sheep fed the aquatic macrophyte Echinochloa stagnina
Small Ruminant Research, 1 (1988) 167-173 Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
167
Performance of Young West African D w a r f Goats and Sheep Fed the Aquatic Macrophyte
Echinochloa stagnina E.A. ADEBOWALE
Institute of Agricultural Research and Training, University of Ife, Moor Plantation, Ibadan (Nigeria) (Accepted 25 March 1988 )
ABSTRACT
Adebowale, E.A., 1988. Performance of young West African Dwarf goats and sheep fed on the aquatic macrophyte Echinocloa stagnina. Small Rumin. Res., 1: 167-173. Voluntary intake, digestion coefficients and nitrogen balance were measured in 24 sheep and 24 goats fed Echinochloa stagnina (P. Beauv), an emergent and floating macrophyte on Nigeria's Lake Kainji. Animals were offered the forage ad libitum and allowed free access to water. Sheep consumed significantly more dry matter (57.4 vs. 51.3 g kg -1 W°7~) than goats. Also, water consumption by sheep was significantly higher than that by goats (2.3 vs. 2.1 mlg-' DM intake). With the exception of acid detergent fibre (ADF), goats and sheep exhibited similar patterns in their ability to digest the various nutrients in the forage. ADF digestibility was 50.4% for sheep and 54.3% for goats. Although both species were in positive nitrogen balance, this was low {0.081 g kg-1 WO75for sheep and 0.11 for goats). With daily digestible DM intake of 32.6 g kg-, WO.75 for goats and 36.1 for sheep, Echinochloa stagnina can maintain sheep and goats throughout the year. This indicates that this macrophyte could be of tremendous importance to livestock feeding, particularly during the dry season when forage is in short supply.
INTRODUCTION T h e g r o w t h of Echinochloa stagnina in a s s o c i a t i o n w i t h E. pyramidalis a n d o t h e r e m e r g e n t a n d f l o a t i n g m a c r o p h y t e s o n L a k e K a i n j i in N i g e r i a h a s b e e n i d e n t i f i e d a n d d e s c r i b e d ( S t a n f i e l d , 1970 ). T h e lake r e s e r v o i r is l o c a t e d 9 ° 5 0 ' l l ° 0 0 ' N a n d 4 ° 2 5 ' E (Fig. 1). I t is a b o u t 136.9 k m m a x i m u m l e n g t h a n d 24.1 k m m a x i m u m w i d t h w i t h a s u r f a c e a r e a o f a p p r o x i m a t e l y 1300 k m 2. A t full v o l u m e , t h e w a t e r level is a t a l t i t u d e 142 m, m a x i m u m d e p t h 60 m a n d m e a n d e p t h 11 m (Obot, 1985 ). T h e c l i m a t e of t h e l o c a t i o n o f t h e lake, t h e h y d r o l o g y a n d c h e m i c a l c h a r a c t e r i s t i c s , a n d t h e geology o f t h e lake site h a v e b e e n rep o r t e d ( M o r t o n a n d O b o t , 1984). G r a s s is v i e w e d as a p r o b l e m to t h e lake h y d r o l o g y a n d to n a v i g a t i o n w i t h
0921-4488/88/$03.50
© 1988 Elsevier Science Publishers B.V.
168 i¢o 00'
N
KEY
7 Open water Savanna zone ~J Echinochloa Grass zone | Mimosa pigro zone
I Mud Communities"
0000 '
SCALE 0
Mono
i •
,
tOKm
~0'
Fig. 1. Vegetationmap of Lake Kainji. small crafts. Hydrologists at the Nigerian National Electricity Power Authority, which generates electricity through the lake, believe that the grass (which covers a total area of 92.4 km 2, about 7.1% of the lake's surface area), has blocked one of the major inflow channels of the reservoir. They also believe that this blockage, together with evapotranspiration from the grass, is responsible for the reduction of the effective lake volume by 15.1%. They have, therefore, advocated eradication of the grass with herbicides. The objective of this study is to assess the usefulness of this forage in terms of voluntary intake, digestibility and nitrogen utilization by some livestock. Since sheep and goats are some of the livestock reared around the lake, the study is also intended to improve their production and productivity, particu-
169 larly during the dry season when forage is scarce for livestock. Successful control of this plant will depend on its economic value to livestock farmers as well as economic benefits of preventing water losses through evapotranspiration. MATERIALSAND METHODS Twenty-four West African Dwarf wether sheep, weighing in average 14.1 kg and 24 West African Dwarf goats, weighing in average 13.2 kg were used. All were yearlings and dry. E. stagnina, about 82% moisture, was cut during the flowering stage using a small boat every morning, partially field-dried to 34.2 % DM, chopped into approximately 2.5 cm length and offered to the animals with a 50% refusal margin. E. stagnina is a perennial grass, occasionally behaving as an annual with straggling or procumbent stems up to about 1 m long under non-flooded conditions and elongating up to 7-9 m in flooded areas. Under flooded conditions, the stem trails on the surface of the water but the leaves and inflorescence are held in an upright position above the water. Leaves are ligulate. The blade is up to 60 cm in length, 2 cm broad at the widest point and hairless, although silicaceous to the touch, with tiny prickles along the margins. The composition of the forage is presented in Table 1. Goats and sheep were separated into groups of four depending on weight. Each group was paired, based mainly on comparable weights. Although animals were weighed weekly, only average weights at the beginning and end of the experiment were used to express voluntary dry matter intake and nitrogen utilization. Animals were confined in individual metabolism crates during the entire period of the experiment. They were fed twice daily and allowed free access to water. Voluntary dry matter intake and water consumption were determined for each animal during a 15-day preliminary period. Ninety percent of the daily voluntary intake was weighed into plastic buckets for each animal for a 10-day collection period and a bulk sample was kept for subsequent analyses. ProceTABLE1 Compositionof Echinochloa stagnina Gross energy (MJ kg-1DM)
19.5
Dry matter content (gkg-1 DM) Ash
Crude protein
ADF1
ADL2
Ether extract
NFE3
98.2
92.1
403.2
45.6
19.5
533.5
1ADF:Aciddetergentfibre; 2ADL:Aciddetergentlignin; ~NFE:Nitrogenfreeextract.
170 dures for s a m p l i n g of feed, collection, h a n d l i n g a n d s a m p l i n g o f faeces a n d u r i n e were similar to t h o s e d e s c r i b e d p r e v i o u s l y (Adebowale, 1983 ).
Chemical analyses P r o x i m a t e analysis o f samples was p e r f o r m e d using s t a n d a r d m e t h o d s (AOAC, 1975) while forage fibre was a n a l y z e d b y t h e m e t h o d of G o e r i n g a n d Van S o e s t (1970). Gross e n e r g y o f feed a n d faeces was d e t e r m i n e d in a Gallenk a m p ballistic b o m b c a l o r i m e t e r using benzoic acid as t h e s t a n d a r d .
Statistical analysis T h e results were c o m p a r e d b y analysis o f v a r i a n c e as described b y Steel a n d T o r r i e (1960). T h e p a i r e d t-test was e m p l o y e d to d e t e r m i n e possible differences b e t w e e n m e a n s for e a c h o f t h e variables b y e a c h species. TABLE 2 Intake, digestibility and nitrogen utilization of Echinochloastagninaby goats and sheep Variables Intake day-' Dry matter gkg- 1BW gkg- 1W°V5 Digestible dry matter gkg- 1BW gkg- 1W°'V5 Digestible energy MJkg- lW°'V5 Water a mlg- 1DM Nutrient digestibility (%) Dry matter Organic matter Crude protein Acid detergent fibre Ether extract Gross energy Utilization of N, gday- 1 N intake N excretion N retention NS: Not significant; *= P < 0.05; BW: Bodyweight. aVoluntary water intake + water intake from feed.
Goat
Sheep
t-value
26.9 51.3
29.6 57.4
0.8 NS 2.4*
17.1 32.6
18.6 36.1
0.5 NS 2.2*
0.58
0.64
0.34 NS
2.1
2.3
2.7*
63.5 67.4 52.4 54.3 61.4 58.3
62.9 68.6 55.5 50.4 60.1 57.5
5.24 4.50 0.74
6.16 5.57 0.59
0.5 NS 1.2 NS 1.5 NS 2.9* 0.6 NS 0.4 NS 1.9" 2.2* 2.7*
171 RESULTS
Table 2 shows intake, nutrient digestibility and nitrogen utilization. All variables were analysed without transformation since their distributions were approximately normal. The DM intake expressed on metabolic size was greater in sheep than goats but non-significant expressed on bodyweight. The ability of goats and sheep to digest the various nutrients present in the forage was similar but goats exhibited a superior ability to digest ADF. Nutritive evaluation of the grass by both species is also in Table 2. Digestible dry matter intake (DDMI) of sheep was significantly higher than goats. However, digestible energy intake of sheep was non-significantly higher than in goats. Nitrogen utilization data in Table 2 show that both goats and sheep were in positive nitrogen balance. However, the nitrogen retained was low (0.74 g or 0.107 gkg -1 W °'~5 for goats and 0.59 g or 0.081 gkg -1 W °'75 for sheep). After initial loss of weight within the first few days of the preliminary period, both species gained weight during the experiment, albeit slowly. DISCUSSION
Nutritive value of E. stagnina used in this investigation was comparable to that of Cynodon nlem[uensis var. nlemfuensis-Cynodon IB8 (Chheda, 1968), and better than that of most hays found in the tropics (Gihad, 1976). The carbohydrate content (both structural and non-structural) was fairly high and the sugar content higher than most forages, which might have accounted for its high palatability to the animals. We found a higher voluntary DM intake by sheep over goats, which, when expressed on metabolic size, conflicts with results of Devendra (1967) and Gihad (1976) but agrees with findings of Adebowale and Ademosun (1985). The water intake of the animals has been related to DM consumed (Koes and Pfander, 1975), which should account for the amount of water consumed to satisfy requirements. The relationship between the water consumption of sheep and goats was similar to that obtained by Adebowale (1983). Differences in digestive ability between goats and sheep for all other nutrients were not significant. Results are in agreement with conclusions of Pant et al. ( 1962 ), Jones et al. ( 1972 ) and Gihad (1976) but vary from those of Baumgardt et al. (1964) who found that goats digested crude protein of hays more extensively. This study showed that goats digested ADF better than did sheep. The explanation that goats pass larger particles through their alimentary tract than sheep, given by McCammon-Feldman et al. (1981) with the capacity of the digestive system of goats proportionately greater than that of steers and sheep, might have accounted for this difference. High water consumptions, which may have promoted faster rumen washout and hence a faster passage, may be
172
responsible for the lower digestibility in sheep (Koes and Pfander, 1975). Increased water intake may also have diluted bacterial populations, hindering substrate-enzyme contact (Baker and Harris, 1947). In this investigation, water intake by sheep was 9% higher than by goats. DDMI was 17.1 gkg -1 BW or 32.6 gkg - 1 W °'75 for goats, and 18.6 gkg - 1 B W or 36.1 gkg-1 WO.75for sheep, respectively. Zemmelink et al. (1984) estimated energy requirements for maintenance and growth of West African Dwarf goats at 26.0 gDOMkg- 1 WO.75and 2.4 gDOMg- 1 liveweight gain, respectively. With an ash content of nearly 10%, it will require 28.9 gDDMIkg -1 W °'75 day -1 of E. stagnina for maintenance alone. It shows that this forage can maintain goats or sheep. In this study, DDMI was 12.7% above maintenance for goats. Ademosun et al. (1985) obtained a 57% DDMI above maintenance when a combination of browse plants (notably Leucaena leucocephalaand Gliricidiasepium) was fed. Since nitrogen balance data in this study showed the animals to be in positive balance, it could be concluded that their nitrogen requirements for maintenance were also being met. This study showed that West African Dwarf sheep and Dwarf goats can be maintained on E. stagnina, although sheep performed better than goats in terms of intake while the reverse was the case for nitrogen utilization. Since seasons do not affect the growth of this floating macrophyte adversely, it is potentially of tremendous importance to the feeding of small ruminant livestock throughout the year. It will be necessary to study the economics of harvest and use by livestock farmers compared to the reduction in possible generation of electricity due to lakewater loss from evapotranspiration and cost of herbicide application against encroachment by E. stagnina. ACKNOWLEDGEMENTS
The author is indebted to Dr. J.S.O. Ayeni, Director, Kainji Lake Research Institute (Nigeria) for the opportunity to work on this macrophyte and the facilities placed at his disposal. Sincere gratitude also goes to Drs. E.A. Obot and T.I. Ibiwoye of the same Institute.
REFERENCES Adebowale, E.A., 1983. The performance of West African Dwarf goats and sheep fed silage and silage plus concentrate. World Rev. Anita. Prod., 19: 15-20. Adebowale, E.A. and Ademosun, A.A., 1985. Studies on the utilization of brewers dried grains by sheep and goats. II. Digestibility, metabolism and rumen studies. Bull. Anita. Health Prod. Afr., 33: 349-355. Ademosun, A.A., Bosman, H.G. and Roessen, P.L., 1985. Nutritional studies with West African Dwarf goats in the humid zone of Nigeria. In: R.T. Wilson and D. Bourzat (Editors), Small
173 Ruminants in African Agriculture. Proceedings Conference ILCA, Addis Ababa, Ethiopia, 30 Sept.-4 Oct., pp. 83-92. AOAC, 1975. Official Methods of Analysis of the Association of Official Agricultural Chemists, 12th edition. AOAC, Washington, DC., U.S.A. Baker, F. and Harris, S.T., 1947. Microbial digestion in the rumen (and caecum) with special reference to decomposition of structural cellulase. Nutr. Abstr. Rev., 17: 3. Baumgardt, B.R., Byer, W.J., Jumah, H.F. and Krueger, C.R., 1964. Digestion in the steer, goat and artificial rumen as measures of forage nutritive value. J. Dairy Sci., 47: 160-164. Chheda, H.R., 1968. Cynodon IB8: An improved variety of Cynodon suitable for pastures in Southern Nigeria. Proc. Agric. Soc. Niger., 5: 46-50. Devendra, C., 1967. Studies in the nutrition of the indigenous goat of Malaya. III. The requirements for liveweight gain. Malaysia Agric. J., 46: 98-118. Gihad, E.A., 1976. Intake, digestibility and nitrogen utilization of tropical natural grass hay by goats and sheep. J. Anim. Sci., 43: 879-883. Goering, H.K. and Van Soest, P.J., 1970. Forage fiber analyses. Agricultural Handbook No. 379, Agricultural Research Service, United States Department of Agriculture, Washington, DC, USA. Jones, G.M., Larsen, R.E., Javed, A.H., Donefer, E. and Gaudreau, J.M., 1972. Voluntary intake and nutrient digestibility of forages by goats and sheep. J. Anita. Sci., 34: 830-838. Koes, R.M. and Pfander, W.H., 1975. Heat load and supplemental effects on performance and nutrient utilization by lambs fed orchard-grass hay. J. Anita. Sci., 40: 313-319. McCammon-Feldman, B., Van Soest, P.J., Hor Vath, P. and McDowell, R.E., 1981. Feeding strategy of the goat. Cornell International Agricultural Mimeo, Cornell University, Ithaca, NY, U.S.A. Morton, A.J. and Obot, E.A., 1984. The control of Echinochloa stagnina by harvesting for dry season livestock fodder in Kainji Lake Basin, Nigeria. A modelling approach. J. Appl. Ecol., 21: 687-694. Obot, E.A., 1985. The management of aquatic macrophyte for livestock fodder: A case study on Echinochloa stagnina in Lake Kainji, Nigeria. Kainji Lake Research Institute, Technical Report Series No. 16. Pant, H.C., Rawat, J.S. and Roy, A., 1962. Studies on rumen physiology. I. Growth of fistulated animals and standardization of methods. Indian J. Dairy Sci., 15: 167-185. Stanfield, D.P., 1970. The flora of Nigeria. Ibadan University Press, Ibadan, Nigeria. Steel, R.G.D. and Torrie, J.H., 1960. Principles and Procedures of Statistics. McGraw-Hill, New York, NY, U.S.A. Zemmelink, G., Tolkamp, B.J. and Meinderts, J.H., 1984. Feed intake and weight gain of West African Dwarf goats. Sheep and goats in the humid zone of West Africa. Proc. Cont. ILCA, Ibadan, Nigeria, 23-26 Jan.
167
Performance of Young West African D w a r f Goats and Sheep Fed the Aquatic Macrophyte
Echinochloa stagnina E.A. ADEBOWALE
Institute of Agricultural Research and Training, University of Ife, Moor Plantation, Ibadan (Nigeria) (Accepted 25 March 1988 )
ABSTRACT
Adebowale, E.A., 1988. Performance of young West African Dwarf goats and sheep fed on the aquatic macrophyte Echinocloa stagnina. Small Rumin. Res., 1: 167-173. Voluntary intake, digestion coefficients and nitrogen balance were measured in 24 sheep and 24 goats fed Echinochloa stagnina (P. Beauv), an emergent and floating macrophyte on Nigeria's Lake Kainji. Animals were offered the forage ad libitum and allowed free access to water. Sheep consumed significantly more dry matter (57.4 vs. 51.3 g kg -1 W°7~) than goats. Also, water consumption by sheep was significantly higher than that by goats (2.3 vs. 2.1 mlg-' DM intake). With the exception of acid detergent fibre (ADF), goats and sheep exhibited similar patterns in their ability to digest the various nutrients in the forage. ADF digestibility was 50.4% for sheep and 54.3% for goats. Although both species were in positive nitrogen balance, this was low {0.081 g kg-1 WO75for sheep and 0.11 for goats). With daily digestible DM intake of 32.6 g kg-, WO.75 for goats and 36.1 for sheep, Echinochloa stagnina can maintain sheep and goats throughout the year. This indicates that this macrophyte could be of tremendous importance to livestock feeding, particularly during the dry season when forage is in short supply.
INTRODUCTION T h e g r o w t h of Echinochloa stagnina in a s s o c i a t i o n w i t h E. pyramidalis a n d o t h e r e m e r g e n t a n d f l o a t i n g m a c r o p h y t e s o n L a k e K a i n j i in N i g e r i a h a s b e e n i d e n t i f i e d a n d d e s c r i b e d ( S t a n f i e l d , 1970 ). T h e lake r e s e r v o i r is l o c a t e d 9 ° 5 0 ' l l ° 0 0 ' N a n d 4 ° 2 5 ' E (Fig. 1). I t is a b o u t 136.9 k m m a x i m u m l e n g t h a n d 24.1 k m m a x i m u m w i d t h w i t h a s u r f a c e a r e a o f a p p r o x i m a t e l y 1300 k m 2. A t full v o l u m e , t h e w a t e r level is a t a l t i t u d e 142 m, m a x i m u m d e p t h 60 m a n d m e a n d e p t h 11 m (Obot, 1985 ). T h e c l i m a t e of t h e l o c a t i o n o f t h e lake, t h e h y d r o l o g y a n d c h e m i c a l c h a r a c t e r i s t i c s , a n d t h e geology o f t h e lake site h a v e b e e n rep o r t e d ( M o r t o n a n d O b o t , 1984). G r a s s is v i e w e d as a p r o b l e m to t h e lake h y d r o l o g y a n d to n a v i g a t i o n w i t h
0921-4488/88/$03.50
© 1988 Elsevier Science Publishers B.V.
168 i¢o 00'
N
KEY
7 Open water Savanna zone ~J Echinochloa Grass zone | Mimosa pigro zone
I Mud Communities"
0000 '
SCALE 0
Mono
i •
,
tOKm
~0'
Fig. 1. Vegetationmap of Lake Kainji. small crafts. Hydrologists at the Nigerian National Electricity Power Authority, which generates electricity through the lake, believe that the grass (which covers a total area of 92.4 km 2, about 7.1% of the lake's surface area), has blocked one of the major inflow channels of the reservoir. They also believe that this blockage, together with evapotranspiration from the grass, is responsible for the reduction of the effective lake volume by 15.1%. They have, therefore, advocated eradication of the grass with herbicides. The objective of this study is to assess the usefulness of this forage in terms of voluntary intake, digestibility and nitrogen utilization by some livestock. Since sheep and goats are some of the livestock reared around the lake, the study is also intended to improve their production and productivity, particu-
169 larly during the dry season when forage is scarce for livestock. Successful control of this plant will depend on its economic value to livestock farmers as well as economic benefits of preventing water losses through evapotranspiration. MATERIALSAND METHODS Twenty-four West African Dwarf wether sheep, weighing in average 14.1 kg and 24 West African Dwarf goats, weighing in average 13.2 kg were used. All were yearlings and dry. E. stagnina, about 82% moisture, was cut during the flowering stage using a small boat every morning, partially field-dried to 34.2 % DM, chopped into approximately 2.5 cm length and offered to the animals with a 50% refusal margin. E. stagnina is a perennial grass, occasionally behaving as an annual with straggling or procumbent stems up to about 1 m long under non-flooded conditions and elongating up to 7-9 m in flooded areas. Under flooded conditions, the stem trails on the surface of the water but the leaves and inflorescence are held in an upright position above the water. Leaves are ligulate. The blade is up to 60 cm in length, 2 cm broad at the widest point and hairless, although silicaceous to the touch, with tiny prickles along the margins. The composition of the forage is presented in Table 1. Goats and sheep were separated into groups of four depending on weight. Each group was paired, based mainly on comparable weights. Although animals were weighed weekly, only average weights at the beginning and end of the experiment were used to express voluntary dry matter intake and nitrogen utilization. Animals were confined in individual metabolism crates during the entire period of the experiment. They were fed twice daily and allowed free access to water. Voluntary dry matter intake and water consumption were determined for each animal during a 15-day preliminary period. Ninety percent of the daily voluntary intake was weighed into plastic buckets for each animal for a 10-day collection period and a bulk sample was kept for subsequent analyses. ProceTABLE1 Compositionof Echinochloa stagnina Gross energy (MJ kg-1DM)
19.5
Dry matter content (gkg-1 DM) Ash
Crude protein
ADF1
ADL2
Ether extract
NFE3
98.2
92.1
403.2
45.6
19.5
533.5
1ADF:Aciddetergentfibre; 2ADL:Aciddetergentlignin; ~NFE:Nitrogenfreeextract.
170 dures for s a m p l i n g of feed, collection, h a n d l i n g a n d s a m p l i n g o f faeces a n d u r i n e were similar to t h o s e d e s c r i b e d p r e v i o u s l y (Adebowale, 1983 ).
Chemical analyses P r o x i m a t e analysis o f samples was p e r f o r m e d using s t a n d a r d m e t h o d s (AOAC, 1975) while forage fibre was a n a l y z e d b y t h e m e t h o d of G o e r i n g a n d Van S o e s t (1970). Gross e n e r g y o f feed a n d faeces was d e t e r m i n e d in a Gallenk a m p ballistic b o m b c a l o r i m e t e r using benzoic acid as t h e s t a n d a r d .
Statistical analysis T h e results were c o m p a r e d b y analysis o f v a r i a n c e as described b y Steel a n d T o r r i e (1960). T h e p a i r e d t-test was e m p l o y e d to d e t e r m i n e possible differences b e t w e e n m e a n s for e a c h o f t h e variables b y e a c h species. TABLE 2 Intake, digestibility and nitrogen utilization of Echinochloastagninaby goats and sheep Variables Intake day-' Dry matter gkg- 1BW gkg- 1W°V5 Digestible dry matter gkg- 1BW gkg- 1W°'V5 Digestible energy MJkg- lW°'V5 Water a mlg- 1DM Nutrient digestibility (%) Dry matter Organic matter Crude protein Acid detergent fibre Ether extract Gross energy Utilization of N, gday- 1 N intake N excretion N retention NS: Not significant; *= P < 0.05; BW: Bodyweight. aVoluntary water intake + water intake from feed.
Goat
Sheep
t-value
26.9 51.3
29.6 57.4
0.8 NS 2.4*
17.1 32.6
18.6 36.1
0.5 NS 2.2*
0.58
0.64
0.34 NS
2.1
2.3
2.7*
63.5 67.4 52.4 54.3 61.4 58.3
62.9 68.6 55.5 50.4 60.1 57.5
5.24 4.50 0.74
6.16 5.57 0.59
0.5 NS 1.2 NS 1.5 NS 2.9* 0.6 NS 0.4 NS 1.9" 2.2* 2.7*
171 RESULTS
Table 2 shows intake, nutrient digestibility and nitrogen utilization. All variables were analysed without transformation since their distributions were approximately normal. The DM intake expressed on metabolic size was greater in sheep than goats but non-significant expressed on bodyweight. The ability of goats and sheep to digest the various nutrients present in the forage was similar but goats exhibited a superior ability to digest ADF. Nutritive evaluation of the grass by both species is also in Table 2. Digestible dry matter intake (DDMI) of sheep was significantly higher than goats. However, digestible energy intake of sheep was non-significantly higher than in goats. Nitrogen utilization data in Table 2 show that both goats and sheep were in positive nitrogen balance. However, the nitrogen retained was low (0.74 g or 0.107 gkg -1 W °'~5 for goats and 0.59 g or 0.081 gkg -1 W °'75 for sheep). After initial loss of weight within the first few days of the preliminary period, both species gained weight during the experiment, albeit slowly. DISCUSSION
Nutritive value of E. stagnina used in this investigation was comparable to that of Cynodon nlem[uensis var. nlemfuensis-Cynodon IB8 (Chheda, 1968), and better than that of most hays found in the tropics (Gihad, 1976). The carbohydrate content (both structural and non-structural) was fairly high and the sugar content higher than most forages, which might have accounted for its high palatability to the animals. We found a higher voluntary DM intake by sheep over goats, which, when expressed on metabolic size, conflicts with results of Devendra (1967) and Gihad (1976) but agrees with findings of Adebowale and Ademosun (1985). The water intake of the animals has been related to DM consumed (Koes and Pfander, 1975), which should account for the amount of water consumed to satisfy requirements. The relationship between the water consumption of sheep and goats was similar to that obtained by Adebowale (1983). Differences in digestive ability between goats and sheep for all other nutrients were not significant. Results are in agreement with conclusions of Pant et al. ( 1962 ), Jones et al. ( 1972 ) and Gihad (1976) but vary from those of Baumgardt et al. (1964) who found that goats digested crude protein of hays more extensively. This study showed that goats digested ADF better than did sheep. The explanation that goats pass larger particles through their alimentary tract than sheep, given by McCammon-Feldman et al. (1981) with the capacity of the digestive system of goats proportionately greater than that of steers and sheep, might have accounted for this difference. High water consumptions, which may have promoted faster rumen washout and hence a faster passage, may be
172
responsible for the lower digestibility in sheep (Koes and Pfander, 1975). Increased water intake may also have diluted bacterial populations, hindering substrate-enzyme contact (Baker and Harris, 1947). In this investigation, water intake by sheep was 9% higher than by goats. DDMI was 17.1 gkg -1 BW or 32.6 gkg - 1 W °'75 for goats, and 18.6 gkg - 1 B W or 36.1 gkg-1 WO.75for sheep, respectively. Zemmelink et al. (1984) estimated energy requirements for maintenance and growth of West African Dwarf goats at 26.0 gDOMkg- 1 WO.75and 2.4 gDOMg- 1 liveweight gain, respectively. With an ash content of nearly 10%, it will require 28.9 gDDMIkg -1 W °'75 day -1 of E. stagnina for maintenance alone. It shows that this forage can maintain goats or sheep. In this study, DDMI was 12.7% above maintenance for goats. Ademosun et al. (1985) obtained a 57% DDMI above maintenance when a combination of browse plants (notably Leucaena leucocephalaand Gliricidiasepium) was fed. Since nitrogen balance data in this study showed the animals to be in positive balance, it could be concluded that their nitrogen requirements for maintenance were also being met. This study showed that West African Dwarf sheep and Dwarf goats can be maintained on E. stagnina, although sheep performed better than goats in terms of intake while the reverse was the case for nitrogen utilization. Since seasons do not affect the growth of this floating macrophyte adversely, it is potentially of tremendous importance to the feeding of small ruminant livestock throughout the year. It will be necessary to study the economics of harvest and use by livestock farmers compared to the reduction in possible generation of electricity due to lakewater loss from evapotranspiration and cost of herbicide application against encroachment by E. stagnina. ACKNOWLEDGEMENTS
The author is indebted to Dr. J.S.O. Ayeni, Director, Kainji Lake Research Institute (Nigeria) for the opportunity to work on this macrophyte and the facilities placed at his disposal. Sincere gratitude also goes to Drs. E.A. Obot and T.I. Ibiwoye of the same Institute.
REFERENCES Adebowale, E.A., 1983. The performance of West African Dwarf goats and sheep fed silage and silage plus concentrate. World Rev. Anita. Prod., 19: 15-20. Adebowale, E.A. and Ademosun, A.A., 1985. Studies on the utilization of brewers dried grains by sheep and goats. II. Digestibility, metabolism and rumen studies. Bull. Anita. Health Prod. Afr., 33: 349-355. Ademosun, A.A., Bosman, H.G. and Roessen, P.L., 1985. Nutritional studies with West African Dwarf goats in the humid zone of Nigeria. In: R.T. Wilson and D. Bourzat (Editors), Small
173 Ruminants in African Agriculture. Proceedings Conference ILCA, Addis Ababa, Ethiopia, 30 Sept.-4 Oct., pp. 83-92. AOAC, 1975. Official Methods of Analysis of the Association of Official Agricultural Chemists, 12th edition. AOAC, Washington, DC., U.S.A. Baker, F. and Harris, S.T., 1947. Microbial digestion in the rumen (and caecum) with special reference to decomposition of structural cellulase. Nutr. Abstr. Rev., 17: 3. Baumgardt, B.R., Byer, W.J., Jumah, H.F. and Krueger, C.R., 1964. Digestion in the steer, goat and artificial rumen as measures of forage nutritive value. J. Dairy Sci., 47: 160-164. Chheda, H.R., 1968. Cynodon IB8: An improved variety of Cynodon suitable for pastures in Southern Nigeria. Proc. Agric. Soc. Niger., 5: 46-50. Devendra, C., 1967. Studies in the nutrition of the indigenous goat of Malaya. III. The requirements for liveweight gain. Malaysia Agric. J., 46: 98-118. Gihad, E.A., 1976. Intake, digestibility and nitrogen utilization of tropical natural grass hay by goats and sheep. J. Anim. Sci., 43: 879-883. Goering, H.K. and Van Soest, P.J., 1970. Forage fiber analyses. Agricultural Handbook No. 379, Agricultural Research Service, United States Department of Agriculture, Washington, DC, USA. Jones, G.M., Larsen, R.E., Javed, A.H., Donefer, E. and Gaudreau, J.M., 1972. Voluntary intake and nutrient digestibility of forages by goats and sheep. J. Anita. Sci., 34: 830-838. Koes, R.M. and Pfander, W.H., 1975. Heat load and supplemental effects on performance and nutrient utilization by lambs fed orchard-grass hay. J. Anita. Sci., 40: 313-319. McCammon-Feldman, B., Van Soest, P.J., Hor Vath, P. and McDowell, R.E., 1981. Feeding strategy of the goat. Cornell International Agricultural Mimeo, Cornell University, Ithaca, NY, U.S.A. Morton, A.J. and Obot, E.A., 1984. The control of Echinochloa stagnina by harvesting for dry season livestock fodder in Kainji Lake Basin, Nigeria. A modelling approach. J. Appl. Ecol., 21: 687-694. Obot, E.A., 1985. The management of aquatic macrophyte for livestock fodder: A case study on Echinochloa stagnina in Lake Kainji, Nigeria. Kainji Lake Research Institute, Technical Report Series No. 16. Pant, H.C., Rawat, J.S. and Roy, A., 1962. Studies on rumen physiology. I. Growth of fistulated animals and standardization of methods. Indian J. Dairy Sci., 15: 167-185. Stanfield, D.P., 1970. The flora of Nigeria. Ibadan University Press, Ibadan, Nigeria. Steel, R.G.D. and Torrie, J.H., 1960. Principles and Procedures of Statistics. McGraw-Hill, New York, NY, U.S.A. Zemmelink, G., Tolkamp, B.J. and Meinderts, J.H., 1984. Feed intake and weight gain of West African Dwarf goats. Sheep and goats in the humid zone of West Africa. Proc. Cont. ILCA, Ibadan, Nigeria, 23-26 Jan.