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Performance of rabbits on Guinea grass and Verano stylo hays in the dry season and effect of concentrate supplementation
Animal Feed Science and Technology 80 (1999) 67±74
Performance of rabbits on Guinea grass and Verano stylo hays in the dry season and effect of concentrate supplementation M.A. Bamikolea, I. Ezenwaa,b,* a
Department of Animal Science, University of Ibadan, Ibadan, Nigeria b Department of Agronomy, University of Ibadan, Ibadan, Nigeria
Received 20 October 1998; received in revised form 11 January 1999; accepted 22 February 1999
Abstract The feasibility of using Verano stylo (Stylosanthes hamata cv. Verano) and Guinea grass (Panicum maximum cv. Ntchisi) hays and their replacement values in concentrate diets for rabbits were determined. The intake and growth of the rabbits were monitored over a 7-week growth study following a 2-week adaptation period, while nutrient digestibility was determined over a 5-day period during the eighth week of the study. The DM intakes of the rabbits during the growth study were 53.1 g/day of the grass concentrate (50 : 50) diet, 56.0 g/day of the all-concentrate diet and 64.8 g/day for the Verano stylo concentrate (50 : 50) diet. The respective weight gains were 5.13, 8.44 and 8.35 g/day. Lower DM intake and consistent losses in weight of the animals were recorded on Verano stylo or Guinea grass alone. Verano stylo hay was better than Guinea grass hay. Thus, concentrate supplementation of forage diets is necessary for rabbits. Replacement of 0.50 of the concentrate with Verano stylo hay gave a similar performance to that for the all-concentrate diet. It is, therefore, possible to reduce the use of concentrates in the diets for growing rabbits in the dry season by replacing part of the diet with Verano stylo hay. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Supplementation; Guinea grass; Verano stylo; Concentrate; Rabbit; Hay
* Corresponding author. Present address: Department of Grassland Management, National Grassland Research Institute, Nishinasuno, Tochigi 329±2747, Japan. Tel.: +81-287-37-7209; fax: +81-287-36-6629; e-mail: [email protected] 0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 3 8 - 3
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M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
1. Introduction In recent times, attention has shifted to rabbits as meat animals. Rabbits are herbivores with post-gastric digestion and can effectively utilise fodders and serve as alternative sources of meat for city dwellers. Acceptable weight gains and overall performance on forages, crop residues and other high fibre agricultural byproducts, which can be obtained free, can be achieved with rabbits without cereal grain or concentrate supplementation (Bayler, 1978; Raharjo et al., 1986; Ridzwan et al., 1993). In southern Nigeria, forage of fair nutritive value is available in the rainy season (April±November) in excess of animal requirements, but scarce in the dry season (Crowder and Chheda, 1977). Possibility exists for conservation of the excess feed in the rainy season for use in the dry season. However, Adegbola et al. (1985), utilising fresh materials, reported that all-forage diets were not suitable for rabbits as they result in weight losses. Concentrate rations are expensive and can be a constraint to widespread exploitation of the potential of rabbits to meet the protein needs of rural and urban poor. The present study was aimed at determining the possibility of replacing part of concentrate diet with hays of productive and high quality Guinea grass and Verano stylo varieties now available (Ezenwa and Aken'Ova, 1998). 2. Materials and methods 2.1. Site of study The experiment was conducted in the Teaching and Research Farm of the University of Ibadan (78200 N, 38500 E, 200 m above sea level) in southern Nigeria. Average temperature and relative humidity during the period of study were 28±348C and 42±50%, respectively. 2.2. Preparation of Guinea grass and Verano stylo hays Fresh Guinea grass (Panicum maximum cv. Ntchisi) and Verano stylo (Stylosanthes hamata cv. Verano) were used. The materials were collected from the last harvest, i.e. the final 6-week regrowth of the rainy season (18 October±30th November, 1997), in order to facilitate hay-making which is preferably done in the dry season. The pastures had been on a regular 6-weekly cutting regime. The grass and legume herbages were chopped to 2 cm lengths and air-dried inside an empty group pen in the Goat Unit of the Farm, with the materials turned over in the mornings and evenings to facilitate uniform drying. After drying, the hays were packed in bags and taken to the rabbitry. 2.3. Animals and housing Thirty rabbits, aged between 8 and 9 weeks old, of mixed breeds purchased from homes in the neighbourhood of the University were used. The average initial weight of
M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
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the rabbits (16 males and 14 females) was 840 g (range 720±950 g). On arrival, the rabbits were given Aminovit, an anti-stress agent, in drinking water. They were treated against endo-parasites with coopane, a brand of piperazine, at the rate of 2 g per litre of water. The animals were housed in individual hutches raised inside the rabbit house that had a concrete floor with metallic roofing sheet. It was designed to ensure cross ventilation and to exclude rodent and other pests. Each rabbit was provided with a metallic feeder hung at a reasonable height in the cage to prevent feed wastage, and weighted clay bowls for water. 2.4. Experimental design The 30 rabbits were balanced for weight and randomly allocated to the five experimental treatments which were Guinea grass alone (Gg), 0.5 Guinea grass 0.5 concentrate (GgC), Verano stylo alone (Vs), 0.5 Verano stylo 0.5 concentrate (VsC) and the control diet of concentrate. Thus, six rabbits were allocated to each of the five treatments with each rabbit serving as a replicate in a completely randomised design. 2.5. Feeding trial This lasted for 8 weeks, but was preceded by a 2-week adaptation period. Each animal was served feed amounting to 50 g DM/kg liveweight (LW)/day during the adaptation period. The amounts of Gg and Vs in the supplemented diets (GgC and VsC) were determined as half of what was consumed by the animals on the all-forage diets (Gg and Vs) during the adaptation period, with daily allowance of 5% above the previous day's consumption. Left-over feed was weighed before next morning feeding to determine the intake for the previous day. Liveweights of the animals were recorded weekly. As indicated above, high mortality was recorded in the animals on Gg during the adaptation period and first week of the growth trial. This was attributable to inadequate nutrition. As a result, concentrate supplement equivalent to one-quarter of the daily feed offered or half of what was given to the animals on 0.5 concentrate supplemented diets was given to the animals. This was done in order to sustain the animals through the period of the growth study. The concentrate was, however, withdrawn a week before the digestibility trial was carried out. 2.6. Digestibility trial This was carried out during the 7 days following the growth trial. Four rabbits were randomly picked from each of the treatments and transferred to metabolic cages with facilities for separate collection of urine and faeces. During the collection period of 5 days, total faeces voided were weighed, wrapped in aluminum foil and dried in forced draught oven at 608C until constant weight. The dried faecal samples for each animal per day over the 5-day collection period were bulked. Representative samples were taken, ground and stored until required for analysis.
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M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
Table 1 Ingredient composition (g/kg) of the concentrate Ingredient
Composition
Maize Dried brewer's grain Palm kernel cake Groundnut cake Fish meal Bone meal Oyster shell Mineral and vitamin mixa Salt
290.0 450.0 130.0 75.0 20.0 15.0 10.0 2.5 2.5
a Composition of the mineral and vitamin mix per 2.5 kg: Vitamin A, 7,000,000 IU; Vitamin D3, 1,400,000 IU; Vitamin E, 5000 IU; Vitamin K, 2.0 g; Vitamin B1, 1.5 g: Vitamin B2, 4.0 g; Vitamin B6, 1.5 g; Vitamin B12, 10 mg; Niacin, 15 g; Pantothenic acid, 5.0 g; Folic acid, 0.5 g; Mn, 75 g; Zn, 45 g; Fe, 20 g; Cu, 5 g; I, 1 g; Se, 100 mg; Co, 200 mg; Choline chloride, 100 g.
2.7. Chemical and statistical analyses The proximate analyses of the feeds and faeces were carried out according to the method of AOAC (1990). Data were subjected to analysis of variance and the means separated by the Duncan multiple range test at 5% level of probability (Gomez and Gomez, 1983). 3. Results The composition of the concentrate diet is shown in Table 1. The concentrate was formulated to meet the basic nutrient requirements as indicated by proximate composition (Table 2). The proximate composition of Guinea grass and Verano stylo is also given in Table 2. The DM content and nitrogen free extract (NFE) of the forages were similar to those of the concentrate. The concentrate had higher contents of crude protein (CP) and ether extract than the forages, whereas the forages had higher contents of crude fibre and ash. The legume, Verano stylo, had higher contents of CP and NFE, but lower content of ash than grass. The forages had similar levels of ether extract. There were significant differences among the diets in their effects on feed intake (FI) and growth performance of the rabbits (Table 3). The highest DM intake was recorded Table 2 Proximate composition (g/kg DM) of the forages and concentrate Composition Dry matter Crude protein Ether extract Crude fibre Ash Nitrogen free extract
Verano stylo 921.1 106.7 16.0 328.0 73.0 476.3
Guinea grass 913.0 71.9 18.2 350.5 119.1 440.3
Concentrate 925.3 185.0 53.0 115.0 57.0 590.0
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Table 3 Feed intake and growth performance of rabbits on different dietary treatments Parameter
Verano stylo (Vs)
Verano stylo concentrate (VsC)
Guinea grass (Gg)
Guinea grass Concentrate concentrate (GgC)
SEm
Dry matter intake (g/day) Weight gain (g/day) Feed conversion efficiency
43.10ca ÿ3.17b ÿ0.07b
64.75a 8.35a 0.13a
43.30c ÿ1.74b ÿ0.04b
53.11b 5.13a 0.10a
2.905 1.346 0.021
a
55.99ab 8.44a 0.15a
Means in a row followed by the same letter are not significantly different at 0.05 level of probability.
with the VsC diet, but this was not significantly higher than that of the concentrate. There was also no significant difference in intake between the GgC and concentrate diets. The lowest DM intakes were recorded in the all-forage diets (VsC and Gg). Animals on VsC, GgC and concentrate diets gained weight while animals on Vs and Gg lost weight. There were no significant differences among the gains of the rabbits on the forage concentrate and concentrate diets, but the gain of rabbits on GgC was about 39% lower than the values of those on the VsC and concentrate diets. The forage concentrate and all-concentrate diets also gave positive feed conversion efficiency, i.e. gain/FI, and the values did not differ significantly among the treatments, while the allforage diets gave negative values. The nutrient intake determined during the 5-day digestibility trial and nutrient digestibility are shown in Table 4. The highest DM intakes were obtained with the VsC and concentrate diets. There was no significant difference between the DM intakes of the Table 4 Feed intakea and nutrient digestibility in rabbits fed different diets Verano stylo (Vs) Daily intake(g/day) Dry matter 47.22c Dry matter (%LW) 6.84a Crude protein 5.02ab Crude fibre 15.43a Organic matter 43.62bc Digestibility coefficients Dry matter 0.502bc Crude protein 0.614a Crude fibre 0.707a Organic matter 0.489b Digestible organic matter 0.464b Digestible energy (MJ/kg DM)b 8.82b 6.96b Metabolisable energy (MJ)c
Verano stylo concentrate (VsC)
Guinea grass (Gg)
Guinea grass concentrate (GgC)
Concentrate
SEm
72.87a 5.51b 10.99a 15.16a 68.21a
36.78d 4.70d 2.67b 13.04a 32.76c
58.79b 5.16bc 8.47ab 11.77ab 54.13ab
64.29ab 4.77cd 11.58a 7.19b 59.00a
2.814 0.127 1.393 1.023 7.318
0.446c 0.504a 0.405c 0.480b 0.405b 7.70b 6.08b
0.805a 0.731a 0.624ab 0.826a 0.656a 12.47a 9.85a
0.052 0.026 0.050 0.033 0.631 0.498
0.562b 0.639a 0.545b 0.584ab 0.521ab 9.91ab 7.82ab
0.528b 0.618a 0.512cd 0.538b 0.469b 8.91b 7.04b
Means in a row followed by the same letter are not significantly different at 0.05 level of probability. Measured during the digestibility trial. b DE 0.19 Digestible organic matter digestibility (DOMD) in g/100g. c Metabolisable energy 00.15 DOMD (MAFF, 1975). a
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rabbits on GgC and the concentrate diets. Intake of Gg was significantly lower than that of any of the other diets. Rabbits on concentrate and VsC diets consumed significantly higher quantities of CP than those that were fed on Gg. The differences among the VsC, concentrate, GgC and Vs in the intake of CP were not significant. CP digestibility, however, was not significantly different among all the diets despite the variations observed in the intake. Intake of CF was significantly higher in the forage and forage concentrate diets than in the concentrate diet, but the CF digestibility values of Vs and C were similar and superior to the other diets. Higher organic matter (OM) intakes were recorded with concentrate and forage concentrate diets. The highest OM digestibility values were recorded in concentrate and VsC diets, but the value obtained for VsC was not significantly higher than values obtained for Vs, Gg and Gc. Digestible energy (DE) and metabolisable energy (ME) followed similar trends as OM digestibility. 4. Discussion In nutrient composition the Guinea grass, Verano stylo and concentrate used in this study are comparable to those used by Adegbola et al. (1985). The CF values of the forages are higher than the values of 10±20% recommended for growing rabbits (Cheeke, 1984). This may explain the generally lower intake and digestibility of the forage diets than of the concentrate, which had a higher CP content and a CF level that is within the recommended range. Adegbola et al. (1985) also reported lower intake of forage diets by rabbits while Hechkman and Mehner (1970) reported lower DM digestibility of forage than of concentrate and concentrate-supplemented forage diets. It is therefore, evident that addition of concentrate improved the performance of rabbits on forage diets. De Blas et al. (1981) also reported that improvement in the value of forage diets was due to the contribution of the concentrate in their mixture. The better quality of the legume hay than the grass hay with or without supplementation was also evident. Legumes are known to be of better quality than grasses which is the reason why grass±legume mixtures are preferred to sole grass swards, fertilised or unfertilised (Ezenwa and Aken'Ova, 1998). The metabolisable energy of all the diets, except the all-concentrate diet fell below the 10 MJ/kg DM reported by Butcher et al. (1983) as being adequate to support growth in rabbits. Higher intake and digestibility were generally obtained in the present study than by Adegbola et al. (1985) who attributed the lower digestibility values obtained in their study to the highly lignified materials used. In the present study, young (6-week old regrowth) materials obtained in the rainy season were used. These materials, therefore, presented no physical limitation to intake. The DM intake of the diets fell within 4.6±7% of body weight reported as optimum for rabbits on dry feed (Prud'hon, 1968). The generally high digestibility values obtained in the present study are in agreement with the reported value of other workers and the fact that rabbits are able to efficiently digest fibrous materials (De Blas et al., 1978). Variations in the digestibility of the nutrients and their intake were explicable by the differences in the CP and CF contents of the diets. This is similar to the report of De Blas et al. (1981) which indicated that fibre content of the diet was the only factor that had a significant effect on intake while differences in CP digestibility were explained by the CP
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levels of the diets. However, the CF of the forage diets did not adversely affect their CP digestibility. Although high intake and digestibility were recorded with the all-forage diets, the CP contents of the forages were too low and probably could not provide adequate levels for growth. Crude protein requirements for rabbits are 110±120 g/kg diet (NRC, 1977) which was only met by the all-concentrate and forage concentrate diets. Consequently, the all-forage diets could not sustain the growth of the rabbits. Similarly, Adegbola et al. (1985) reported weight losses and negative N balances in rabbits on all-forage diets; only the all-concentrate diet gave a positive N balance of 0.7 g/day. In the present study, 50% supplementation was adequate to improve the performance of the rabbits on the forage diets to the level of the all-concentrate diet. The weight gains obtained are lower than those reported by Harris et al. (1981) who fed forages in dried meal form to weanling rabbits (about 4 weeks old). Besides the nature of the forages used, the lower values obtained in this study may be due to the high ambient temperature and low relative humidity prevailing during the period of the study (dry season). Our data are, however, comparable to those of Adegbola et al. (1985) and Adu et al. (1998). 5. Conclusion Guinea grass and Verano stylo hays made from excess growth in the rainy season can replace up to 0.50 of concentrate in the diets of rabbits in the dry season, and give similar performance to that of an all-concentrate diet. This will reduce the overall cost of feeding and be more profitable. References Adegbola, T.A., Tibi, E.U., Asugwa, D.C., 1985. Feed intake and digestibility of rabbits on all-forage, forage plus concentrate and all-concentrate diets. J. Anim. Prod. Res. 5, 185±191. Adu, O.A., Tewe, O.O., Iyayi, E.A., 1998. Effects of feeding sweet potato tuber and leaves and vines supplemented with minerals on the performance of rabbits. In: Oduguwa, O.O., Fanimo, A.O., Osinowo, O.A. (Eds.), Animal Agriculture in West Africa: The Sustainability Question. Proc. of the Silver Anniversary Conference of the Nigerian Society of Animal Production (NSAP), held at the University of Agriculture (UNAAB), Abeokuta, Nigeria, 21±26 March 1998, pp. 556±557. Association of Official Analytical Chemists (AOAC), 1990. Official Methods of Analysis, 15th ed., Association of Official Analytical Chemists, Washington, DC. Bayler, H.S., 1978. Comparative morphology of the hindgut and its nutritional significance. J. Anim. Sci. 46, 1800±1802. Butcher, C., Byrant, M.J., Owen, E., 1983. The effect of dietary metabolisable energy concentration upon the pre- and post-weaning performance of growing rabbits. Anim. Prod. 36, 229±236. Cheeke, P.R., 1984. Rabbit nutrition and feeding: recent advances and future perspective. J. Appl. Rabbit Res. 7, 31±37. Crowder, L.V., Chheda, H.R., 1977. Forage and fodder crops. In: Leakey, C.L.A., Willis, J.B. (Eds.), Food Crops of the Lowland Humid Tropics. Oxford University Press, London, pp. 127±159. De Blas, J.C., Torres, A., Perez, E., Cassado, M., 1978. La Alimentation del Conejo, 2nd ed. ETSIA, Madrid, Spain. De Blas, J.C., Perez, E., Fraga Maria, J., Rodrquez, M., Galvez, J.F., 1981. Effect of diet on feed intake and growth of rabbits from weaning to slaughter at different ages and weights. J. Anim. Sci. 52, 1225±1232.
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Ezenwa, I., Aken'Ova, M.E., 1998. Performance of mixtures of selected grasses and adapted herbaceous legumes in southwest Nigeria. Trop. Grassl. 32, 131±138. Gomez, A.K., Gomez, A.A., 1983. Statistical Procedures for Agricultural Research, 2nd ed. International Rice Research Institute, The Philippines. Harris, D.J., Cheeke, P.R., Telek, L., Patton, N.M., 1981. Utilization of alfalfa meal and tropical forages by weanling rabbits. J. Appl. Rabbit Res. 4, 4±9. Hechkman, F.W., Mehner, A., 1970. Experiments on protein and crude fibre levels in a complete diet for young fattening rabbits (German) (De). Archiv. Fur Geflugelzucht and Kletier Kunde 19, 29±43. Ministry of Agriculture, Forestry and Food (MAFF), 1975. Energy allowances and composition of feeding stuffs for ruminants. Tech. Bull. 33. Ministry of Agriculture, Fisheries and Food, HMSO, London. National Research Council (NRC), 1977. Nutrient requirements of rabbits, 2nd ed. National Academy of Sciences, Washington, DC. Prud'hon, M., 1968. Appetite in rabbits given dry feed (Italian). Coniglicoltura 5, 23±32. Raharjo, Y.C., Cheeke, P.R., Patton, N.M., 1986. Growth and reproductive performance of rabbits on a moderately low crude protein diet with or without methionine or urea supplementation. J. Anim. Sci. 63, 795±803. Ridzwan, B.H., Fadzli, M.K., Rozali, M.B.O., Daniel, F.F., Chin Ibrahim, B.M., Faridnordin, B.I., 1993. Evaluation of cocoa pod husks on the performance of rabbits. Anim. Feed Sci. Technol. 40, 267±272.
Performance of rabbits on Guinea grass and Verano stylo hays in the dry season and effect of concentrate supplementation M.A. Bamikolea, I. Ezenwaa,b,* a
Department of Animal Science, University of Ibadan, Ibadan, Nigeria b Department of Agronomy, University of Ibadan, Ibadan, Nigeria
Received 20 October 1998; received in revised form 11 January 1999; accepted 22 February 1999
Abstract The feasibility of using Verano stylo (Stylosanthes hamata cv. Verano) and Guinea grass (Panicum maximum cv. Ntchisi) hays and their replacement values in concentrate diets for rabbits were determined. The intake and growth of the rabbits were monitored over a 7-week growth study following a 2-week adaptation period, while nutrient digestibility was determined over a 5-day period during the eighth week of the study. The DM intakes of the rabbits during the growth study were 53.1 g/day of the grass concentrate (50 : 50) diet, 56.0 g/day of the all-concentrate diet and 64.8 g/day for the Verano stylo concentrate (50 : 50) diet. The respective weight gains were 5.13, 8.44 and 8.35 g/day. Lower DM intake and consistent losses in weight of the animals were recorded on Verano stylo or Guinea grass alone. Verano stylo hay was better than Guinea grass hay. Thus, concentrate supplementation of forage diets is necessary for rabbits. Replacement of 0.50 of the concentrate with Verano stylo hay gave a similar performance to that for the all-concentrate diet. It is, therefore, possible to reduce the use of concentrates in the diets for growing rabbits in the dry season by replacing part of the diet with Verano stylo hay. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Supplementation; Guinea grass; Verano stylo; Concentrate; Rabbit; Hay
* Corresponding author. Present address: Department of Grassland Management, National Grassland Research Institute, Nishinasuno, Tochigi 329±2747, Japan. Tel.: +81-287-37-7209; fax: +81-287-36-6629; e-mail: [email protected] 0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 3 8 - 3
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M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
1. Introduction In recent times, attention has shifted to rabbits as meat animals. Rabbits are herbivores with post-gastric digestion and can effectively utilise fodders and serve as alternative sources of meat for city dwellers. Acceptable weight gains and overall performance on forages, crop residues and other high fibre agricultural byproducts, which can be obtained free, can be achieved with rabbits without cereal grain or concentrate supplementation (Bayler, 1978; Raharjo et al., 1986; Ridzwan et al., 1993). In southern Nigeria, forage of fair nutritive value is available in the rainy season (April±November) in excess of animal requirements, but scarce in the dry season (Crowder and Chheda, 1977). Possibility exists for conservation of the excess feed in the rainy season for use in the dry season. However, Adegbola et al. (1985), utilising fresh materials, reported that all-forage diets were not suitable for rabbits as they result in weight losses. Concentrate rations are expensive and can be a constraint to widespread exploitation of the potential of rabbits to meet the protein needs of rural and urban poor. The present study was aimed at determining the possibility of replacing part of concentrate diet with hays of productive and high quality Guinea grass and Verano stylo varieties now available (Ezenwa and Aken'Ova, 1998). 2. Materials and methods 2.1. Site of study The experiment was conducted in the Teaching and Research Farm of the University of Ibadan (78200 N, 38500 E, 200 m above sea level) in southern Nigeria. Average temperature and relative humidity during the period of study were 28±348C and 42±50%, respectively. 2.2. Preparation of Guinea grass and Verano stylo hays Fresh Guinea grass (Panicum maximum cv. Ntchisi) and Verano stylo (Stylosanthes hamata cv. Verano) were used. The materials were collected from the last harvest, i.e. the final 6-week regrowth of the rainy season (18 October±30th November, 1997), in order to facilitate hay-making which is preferably done in the dry season. The pastures had been on a regular 6-weekly cutting regime. The grass and legume herbages were chopped to 2 cm lengths and air-dried inside an empty group pen in the Goat Unit of the Farm, with the materials turned over in the mornings and evenings to facilitate uniform drying. After drying, the hays were packed in bags and taken to the rabbitry. 2.3. Animals and housing Thirty rabbits, aged between 8 and 9 weeks old, of mixed breeds purchased from homes in the neighbourhood of the University were used. The average initial weight of
M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
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the rabbits (16 males and 14 females) was 840 g (range 720±950 g). On arrival, the rabbits were given Aminovit, an anti-stress agent, in drinking water. They were treated against endo-parasites with coopane, a brand of piperazine, at the rate of 2 g per litre of water. The animals were housed in individual hutches raised inside the rabbit house that had a concrete floor with metallic roofing sheet. It was designed to ensure cross ventilation and to exclude rodent and other pests. Each rabbit was provided with a metallic feeder hung at a reasonable height in the cage to prevent feed wastage, and weighted clay bowls for water. 2.4. Experimental design The 30 rabbits were balanced for weight and randomly allocated to the five experimental treatments which were Guinea grass alone (Gg), 0.5 Guinea grass 0.5 concentrate (GgC), Verano stylo alone (Vs), 0.5 Verano stylo 0.5 concentrate (VsC) and the control diet of concentrate. Thus, six rabbits were allocated to each of the five treatments with each rabbit serving as a replicate in a completely randomised design. 2.5. Feeding trial This lasted for 8 weeks, but was preceded by a 2-week adaptation period. Each animal was served feed amounting to 50 g DM/kg liveweight (LW)/day during the adaptation period. The amounts of Gg and Vs in the supplemented diets (GgC and VsC) were determined as half of what was consumed by the animals on the all-forage diets (Gg and Vs) during the adaptation period, with daily allowance of 5% above the previous day's consumption. Left-over feed was weighed before next morning feeding to determine the intake for the previous day. Liveweights of the animals were recorded weekly. As indicated above, high mortality was recorded in the animals on Gg during the adaptation period and first week of the growth trial. This was attributable to inadequate nutrition. As a result, concentrate supplement equivalent to one-quarter of the daily feed offered or half of what was given to the animals on 0.5 concentrate supplemented diets was given to the animals. This was done in order to sustain the animals through the period of the growth study. The concentrate was, however, withdrawn a week before the digestibility trial was carried out. 2.6. Digestibility trial This was carried out during the 7 days following the growth trial. Four rabbits were randomly picked from each of the treatments and transferred to metabolic cages with facilities for separate collection of urine and faeces. During the collection period of 5 days, total faeces voided were weighed, wrapped in aluminum foil and dried in forced draught oven at 608C until constant weight. The dried faecal samples for each animal per day over the 5-day collection period were bulked. Representative samples were taken, ground and stored until required for analysis.
70
M.A. Bamikole, I. Ezenwa / Animal Feed Science and Technology 80 (1999) 67±74
Table 1 Ingredient composition (g/kg) of the concentrate Ingredient
Composition
Maize Dried brewer's grain Palm kernel cake Groundnut cake Fish meal Bone meal Oyster shell Mineral and vitamin mixa Salt
290.0 450.0 130.0 75.0 20.0 15.0 10.0 2.5 2.5
a Composition of the mineral and vitamin mix per 2.5 kg: Vitamin A, 7,000,000 IU; Vitamin D3, 1,400,000 IU; Vitamin E, 5000 IU; Vitamin K, 2.0 g; Vitamin B1, 1.5 g: Vitamin B2, 4.0 g; Vitamin B6, 1.5 g; Vitamin B12, 10 mg; Niacin, 15 g; Pantothenic acid, 5.0 g; Folic acid, 0.5 g; Mn, 75 g; Zn, 45 g; Fe, 20 g; Cu, 5 g; I, 1 g; Se, 100 mg; Co, 200 mg; Choline chloride, 100 g.
2.7. Chemical and statistical analyses The proximate analyses of the feeds and faeces were carried out according to the method of AOAC (1990). Data were subjected to analysis of variance and the means separated by the Duncan multiple range test at 5% level of probability (Gomez and Gomez, 1983). 3. Results The composition of the concentrate diet is shown in Table 1. The concentrate was formulated to meet the basic nutrient requirements as indicated by proximate composition (Table 2). The proximate composition of Guinea grass and Verano stylo is also given in Table 2. The DM content and nitrogen free extract (NFE) of the forages were similar to those of the concentrate. The concentrate had higher contents of crude protein (CP) and ether extract than the forages, whereas the forages had higher contents of crude fibre and ash. The legume, Verano stylo, had higher contents of CP and NFE, but lower content of ash than grass. The forages had similar levels of ether extract. There were significant differences among the diets in their effects on feed intake (FI) and growth performance of the rabbits (Table 3). The highest DM intake was recorded Table 2 Proximate composition (g/kg DM) of the forages and concentrate Composition Dry matter Crude protein Ether extract Crude fibre Ash Nitrogen free extract
Verano stylo 921.1 106.7 16.0 328.0 73.0 476.3
Guinea grass 913.0 71.9 18.2 350.5 119.1 440.3
Concentrate 925.3 185.0 53.0 115.0 57.0 590.0
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Table 3 Feed intake and growth performance of rabbits on different dietary treatments Parameter
Verano stylo (Vs)
Verano stylo concentrate (VsC)
Guinea grass (Gg)
Guinea grass Concentrate concentrate (GgC)
SEm
Dry matter intake (g/day) Weight gain (g/day) Feed conversion efficiency
43.10ca ÿ3.17b ÿ0.07b
64.75a 8.35a 0.13a
43.30c ÿ1.74b ÿ0.04b
53.11b 5.13a 0.10a
2.905 1.346 0.021
a
55.99ab 8.44a 0.15a
Means in a row followed by the same letter are not significantly different at 0.05 level of probability.
with the VsC diet, but this was not significantly higher than that of the concentrate. There was also no significant difference in intake between the GgC and concentrate diets. The lowest DM intakes were recorded in the all-forage diets (VsC and Gg). Animals on VsC, GgC and concentrate diets gained weight while animals on Vs and Gg lost weight. There were no significant differences among the gains of the rabbits on the forage concentrate and concentrate diets, but the gain of rabbits on GgC was about 39% lower than the values of those on the VsC and concentrate diets. The forage concentrate and all-concentrate diets also gave positive feed conversion efficiency, i.e. gain/FI, and the values did not differ significantly among the treatments, while the allforage diets gave negative values. The nutrient intake determined during the 5-day digestibility trial and nutrient digestibility are shown in Table 4. The highest DM intakes were obtained with the VsC and concentrate diets. There was no significant difference between the DM intakes of the Table 4 Feed intakea and nutrient digestibility in rabbits fed different diets Verano stylo (Vs) Daily intake(g/day) Dry matter 47.22c Dry matter (%LW) 6.84a Crude protein 5.02ab Crude fibre 15.43a Organic matter 43.62bc Digestibility coefficients Dry matter 0.502bc Crude protein 0.614a Crude fibre 0.707a Organic matter 0.489b Digestible organic matter 0.464b Digestible energy (MJ/kg DM)b 8.82b 6.96b Metabolisable energy (MJ)c
Verano stylo concentrate (VsC)
Guinea grass (Gg)
Guinea grass concentrate (GgC)
Concentrate
SEm
72.87a 5.51b 10.99a 15.16a 68.21a
36.78d 4.70d 2.67b 13.04a 32.76c
58.79b 5.16bc 8.47ab 11.77ab 54.13ab
64.29ab 4.77cd 11.58a 7.19b 59.00a
2.814 0.127 1.393 1.023 7.318
0.446c 0.504a 0.405c 0.480b 0.405b 7.70b 6.08b
0.805a 0.731a 0.624ab 0.826a 0.656a 12.47a 9.85a
0.052 0.026 0.050 0.033 0.631 0.498
0.562b 0.639a 0.545b 0.584ab 0.521ab 9.91ab 7.82ab
0.528b 0.618a 0.512cd 0.538b 0.469b 8.91b 7.04b
Means in a row followed by the same letter are not significantly different at 0.05 level of probability. Measured during the digestibility trial. b DE 0.19 Digestible organic matter digestibility (DOMD) in g/100g. c Metabolisable energy 00.15 DOMD (MAFF, 1975). a
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rabbits on GgC and the concentrate diets. Intake of Gg was significantly lower than that of any of the other diets. Rabbits on concentrate and VsC diets consumed significantly higher quantities of CP than those that were fed on Gg. The differences among the VsC, concentrate, GgC and Vs in the intake of CP were not significant. CP digestibility, however, was not significantly different among all the diets despite the variations observed in the intake. Intake of CF was significantly higher in the forage and forage concentrate diets than in the concentrate diet, but the CF digestibility values of Vs and C were similar and superior to the other diets. Higher organic matter (OM) intakes were recorded with concentrate and forage concentrate diets. The highest OM digestibility values were recorded in concentrate and VsC diets, but the value obtained for VsC was not significantly higher than values obtained for Vs, Gg and Gc. Digestible energy (DE) and metabolisable energy (ME) followed similar trends as OM digestibility. 4. Discussion In nutrient composition the Guinea grass, Verano stylo and concentrate used in this study are comparable to those used by Adegbola et al. (1985). The CF values of the forages are higher than the values of 10±20% recommended for growing rabbits (Cheeke, 1984). This may explain the generally lower intake and digestibility of the forage diets than of the concentrate, which had a higher CP content and a CF level that is within the recommended range. Adegbola et al. (1985) also reported lower intake of forage diets by rabbits while Hechkman and Mehner (1970) reported lower DM digestibility of forage than of concentrate and concentrate-supplemented forage diets. It is therefore, evident that addition of concentrate improved the performance of rabbits on forage diets. De Blas et al. (1981) also reported that improvement in the value of forage diets was due to the contribution of the concentrate in their mixture. The better quality of the legume hay than the grass hay with or without supplementation was also evident. Legumes are known to be of better quality than grasses which is the reason why grass±legume mixtures are preferred to sole grass swards, fertilised or unfertilised (Ezenwa and Aken'Ova, 1998). The metabolisable energy of all the diets, except the all-concentrate diet fell below the 10 MJ/kg DM reported by Butcher et al. (1983) as being adequate to support growth in rabbits. Higher intake and digestibility were generally obtained in the present study than by Adegbola et al. (1985) who attributed the lower digestibility values obtained in their study to the highly lignified materials used. In the present study, young (6-week old regrowth) materials obtained in the rainy season were used. These materials, therefore, presented no physical limitation to intake. The DM intake of the diets fell within 4.6±7% of body weight reported as optimum for rabbits on dry feed (Prud'hon, 1968). The generally high digestibility values obtained in the present study are in agreement with the reported value of other workers and the fact that rabbits are able to efficiently digest fibrous materials (De Blas et al., 1978). Variations in the digestibility of the nutrients and their intake were explicable by the differences in the CP and CF contents of the diets. This is similar to the report of De Blas et al. (1981) which indicated that fibre content of the diet was the only factor that had a significant effect on intake while differences in CP digestibility were explained by the CP
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levels of the diets. However, the CF of the forage diets did not adversely affect their CP digestibility. Although high intake and digestibility were recorded with the all-forage diets, the CP contents of the forages were too low and probably could not provide adequate levels for growth. Crude protein requirements for rabbits are 110±120 g/kg diet (NRC, 1977) which was only met by the all-concentrate and forage concentrate diets. Consequently, the all-forage diets could not sustain the growth of the rabbits. Similarly, Adegbola et al. (1985) reported weight losses and negative N balances in rabbits on all-forage diets; only the all-concentrate diet gave a positive N balance of 0.7 g/day. In the present study, 50% supplementation was adequate to improve the performance of the rabbits on the forage diets to the level of the all-concentrate diet. The weight gains obtained are lower than those reported by Harris et al. (1981) who fed forages in dried meal form to weanling rabbits (about 4 weeks old). Besides the nature of the forages used, the lower values obtained in this study may be due to the high ambient temperature and low relative humidity prevailing during the period of the study (dry season). Our data are, however, comparable to those of Adegbola et al. (1985) and Adu et al. (1998). 5. Conclusion Guinea grass and Verano stylo hays made from excess growth in the rainy season can replace up to 0.50 of concentrate in the diets of rabbits in the dry season, and give similar performance to that of an all-concentrate diet. This will reduce the overall cost of feeding and be more profitable. References Adegbola, T.A., Tibi, E.U., Asugwa, D.C., 1985. Feed intake and digestibility of rabbits on all-forage, forage plus concentrate and all-concentrate diets. J. Anim. Prod. Res. 5, 185±191. Adu, O.A., Tewe, O.O., Iyayi, E.A., 1998. Effects of feeding sweet potato tuber and leaves and vines supplemented with minerals on the performance of rabbits. In: Oduguwa, O.O., Fanimo, A.O., Osinowo, O.A. (Eds.), Animal Agriculture in West Africa: The Sustainability Question. Proc. of the Silver Anniversary Conference of the Nigerian Society of Animal Production (NSAP), held at the University of Agriculture (UNAAB), Abeokuta, Nigeria, 21±26 March 1998, pp. 556±557. Association of Official Analytical Chemists (AOAC), 1990. Official Methods of Analysis, 15th ed., Association of Official Analytical Chemists, Washington, DC. Bayler, H.S., 1978. Comparative morphology of the hindgut and its nutritional significance. J. Anim. Sci. 46, 1800±1802. Butcher, C., Byrant, M.J., Owen, E., 1983. The effect of dietary metabolisable energy concentration upon the pre- and post-weaning performance of growing rabbits. Anim. Prod. 36, 229±236. Cheeke, P.R., 1984. Rabbit nutrition and feeding: recent advances and future perspective. J. Appl. Rabbit Res. 7, 31±37. Crowder, L.V., Chheda, H.R., 1977. Forage and fodder crops. In: Leakey, C.L.A., Willis, J.B. (Eds.), Food Crops of the Lowland Humid Tropics. Oxford University Press, London, pp. 127±159. De Blas, J.C., Torres, A., Perez, E., Cassado, M., 1978. La Alimentation del Conejo, 2nd ed. ETSIA, Madrid, Spain. De Blas, J.C., Perez, E., Fraga Maria, J., Rodrquez, M., Galvez, J.F., 1981. Effect of diet on feed intake and growth of rabbits from weaning to slaughter at different ages and weights. J. Anim. Sci. 52, 1225±1232.
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Ezenwa, I., Aken'Ova, M.E., 1998. Performance of mixtures of selected grasses and adapted herbaceous legumes in southwest Nigeria. Trop. Grassl. 32, 131±138. Gomez, A.K., Gomez, A.A., 1983. Statistical Procedures for Agricultural Research, 2nd ed. International Rice Research Institute, The Philippines. Harris, D.J., Cheeke, P.R., Telek, L., Patton, N.M., 1981. Utilization of alfalfa meal and tropical forages by weanling rabbits. J. Appl. Rabbit Res. 4, 4±9. Hechkman, F.W., Mehner, A., 1970. Experiments on protein and crude fibre levels in a complete diet for young fattening rabbits (German) (De). Archiv. Fur Geflugelzucht and Kletier Kunde 19, 29±43. Ministry of Agriculture, Forestry and Food (MAFF), 1975. Energy allowances and composition of feeding stuffs for ruminants. Tech. Bull. 33. Ministry of Agriculture, Fisheries and Food, HMSO, London. National Research Council (NRC), 1977. Nutrient requirements of rabbits, 2nd ed. National Academy of Sciences, Washington, DC. Prud'hon, M., 1968. Appetite in rabbits given dry feed (Italian). Coniglicoltura 5, 23±32. Raharjo, Y.C., Cheeke, P.R., Patton, N.M., 1986. Growth and reproductive performance of rabbits on a moderately low crude protein diet with or without methionine or urea supplementation. J. Anim. Sci. 63, 795±803. Ridzwan, B.H., Fadzli, M.K., Rozali, M.B.O., Daniel, F.F., Chin Ibrahim, B.M., Faridnordin, B.I., 1993. Evaluation of cocoa pod husks on the performance of rabbits. Anim. Feed Sci. Technol. 40, 267±272.