Effect of Replacement of Groundnut Cake with Urea-treated Neem (Azadirachta indica A. juss) Seed Kernel Cake on Nutrient Utilisation in Lambs

The effect of urea treatment on chemical composition of neem seed kernel cake (NSKC) was investigated by soaking the cake in 2.1% urea solution (1.2 l $kg^{-1}$ NSKC) for five days. The effect on utilisation of nutrients by replacing groundnut cake (GNC) (30%) with urea-treated neem seed kernel cake (UTNSKC) (33%) in a concentrate mixture fed to meet 70% of the protein requirements of lambs (8 males and 8 females), was monitored in a digestibility study. Following urea treatment of NSKC only 9.5% of urea was hydrolysed and the crude protein content of the cake was increased by 6.65%. The tannin content in depulped neem seeds was 37% catechin equivalent. Whereas feeding UTNSKC had no effect on intake of dry matter (72.5 vs 66.3 g/kg $BW^{0.75}day^{-1}$) and digestibility of crude fibre (41.3 vs 43.4%), the cake depressed (p<0.01) the percent digestibility of dry matter (63.7 vs 70.2), crude protein (63.2 vs 70.2), nitrogen free extract (73.8 vs 80.5) and gross energy (64.3 vs 69.1). Digestibility of ether extract (75.8 vs 70.9%) was higher (p<0.05) in animals offered UTNSKC. The nutritive value of the composite ration consumed by lambs offered UTNSKC was lower (p<0.01) in terms of total digestible nutrients (64.7 vs 70.2%) and digestible energy (2.8 vs 3.0 Kcal/g DM). Intake of digestible energy (199.8 vs 194.1 Kcal/kg $BW^{0.75}day^{-1}$) and retention of nitrogen (7.53 vs 8.23 g $day^{-1}$) and calcium (2.12 vs 1.84 g $day^{-1}$) were comparable on the 2 rations. Animals fed UTNSKC retained less (p<0.01) phosphorus (0.37 vs 1.05 g $day^{-1}$). The results indicate that urea treatment increased the protein level of NSKC whereas feeding the treated cake as a replacement of GNC, lowered the digestibility of nutrients and retention of phosphorus.