Growth, Nutrient Digestibility and Nitrogen Retention of Growing Bucks Fed Gamba Grass Supplemented with Acacia Leaf Meal-Based Concentrates

Abstract

The study was conducted to evaluate the performance of growing bucks fed Gamba grass supplemented with different Acacia leaf meal-based concentrate in the semi-arid zone of Nigeria. Twenty (20) growing bucks with an average weight of 11.50 kg were assigned to four (4) dietary treatments (Acacia nolitica, Acacia albida, Acacia senegal and Acacia sieberina) in a completely randomized design. The results for chemical composition of different Acacia species revealed the dry matter (94.84 – 95.80 %), crude protein (12.42 – 17.78 %), ether extract (2.08 – 3.58 %), ash content (7.58 – 9.52 %), NFE (43.43 – 51.69 %), ADF (20.64 – 25.11 %), NDF (24.89 – 30.68 %) and lignin (7.36 – 9.14 %) while Gamba grass recorded dry matter (91.24%), crude protein (9.89%), ether extract (2.09%), ash (7.31%), NFE (37.41%), ADF (35.64%), NDF (43.17%) and lignin (12.71%).The chemical composition of the experimental diets had  dry matter (89.25 – 94.74 %), crude protein (10.88 – 15.82  %), ether extract (2.73 – 2.99 %), ash (7.72 – 8.55 %), NFE (38.41 – 46.39 %), ADF (22.73 – 28.01 %), NDF (27.60 – 34.44 %) and lignin (8.13 – 10.10 %), respectively. There was significant (P<0.05) effect of different Acacia species on total feed intake, daily feed intake, weight gain and daily weight gain. While non-significant (P>0.05) effect was observed for initial weight, final weight and feed conversion ratio (FCR). The following ranges for initial weight (11.50 – 11.63 kg/buck), final weight (13.28 – 13.70 kg/buck) and FCR (12.26 – 14.26) were observed. Higher (P<0.05) total feed intake (23217.00 g/buck) and daily feed intake (331.68 g/buck/day) were recorded for bucks fed A. sieberina based diet while lower (P<0.05) total feed intake (20972.00 g/buck) and daily feed intake (299.60 g/buck/day) were recorded for bucks fed A. senegal based diet. Higher (P<0.05) weight gain (2.20 kg/buck) and daily weight gain (31.46 g/buck/day) were obtained for bucks fed A.nolitica based diet while lower (P<0.05) weight gain (1.78 kg/buck) and daily weight gain (25.36 g/buck/day) were recorded for bucks fed A. senegal and A. sieberina based diets, respectively. For apparent nutrient digestibility, higher (P<0.05) dry matter (60.70%), ADF (54.22%) and NDF (55.45%) digestibilities were recorded by bucks fed A. nolitica based diet while lower (P<0.05) dry matter (54.43%), ADF (52.10%) and NDF (52.00%) digestibilities were recorded by bucks fed A. sieberina based diet. Higher (P<0.05) crude protein (64.08%) digestibility was obtained by bucks fed A. senegal based diet while lower (P<0.05) crude protein (58.74%) digestibility was recorded by bucks fed A. nolitica based diet. Significant (P<0.05) effect of different Acacia species was obtained for nitrogen retention parameters except nitrogen intake which ranged from 51.26 to 53.38 g/buck/day.  Faecal nitrogen (15.43 g/buck/day) and urinary nitrogen (11.99 g/buck/day) were higher (P<0.05) in bucks fed A. senegal based diets while lower (P<0.05) faecal nitrogen (14.31 g/buck/day) and urinary nitrogen (10.16 g/buck/day) were recorded in bucks fed A. nolitica based diet. Higher (P<0.05) nitrogen retained (26.79 g/buck/day) and nitrogen retained as % intake (52.26%) were recorded in bucks fed A. nolitica based diet while lower (P<0.05) nitrogen retained (25.96 g/buck/day) and nitrogen retained as % intake (48.63%) were recorded in bucks fed A. senegal based diet. In conclusion, the supplementation of Gamba grass with Acacia species not only promotes enhanced growth performance in bucks but also offers a cost-effective feeding solution for small ruminant production in Nigeria's semi-arid regions. Based on these results, all the Acacia species can be recommended to farmers when they are well formulated in a balanced proportion.