The effect of supplementary concentrate on nutritive value of feed and nitrogen and energy balance in goats fed on forage rye (Secale cereale L.) silage

To determine the feeding value of rye (Secale cereale L.) silage, nutritive value of feed and nitrogen and energy balance were measure din goats fed on rye silage with or without supplementary concentrate. Rye silage was fed ad libitum to twelve goats grouped into tetrads. Concentrate was supplemented at 0, 0.1, 0.5 and 1% of initial liveweight for group I, II, III and IV respectively. Nitrogen intake (NI), digestible nitrogen (DN) and nitrogen lost in feces (FN) increased according to increasing supplementary level of concentrate and the figures were significantly higher (p0.05) in groups supplemented at 0.5 and 1% of liveweight. Nitrogen balance was 0.3, -0.1, 1.5 and 1.1 g/day for group I, II, III and IV respectively, and retained nitrogen (RN) of group III exhibited significant difference from group I and II. RN had significant correlation (p0.05) with NI, FN and DN and not with nitrogen lost in urine. There were no significant differences between groups in GE and DE but ME increased significantly (p0.05) with increasing supplementary level of concentrate. TDN and DCP exhibited similar patterns with ME. Intake of gross energy was statistically higher (p0.05) in group III and IV than in group I and II. But energy losses had no significant differences between groups except loss to methane. Heat production and fecal energy were main factors n energy loss. Means for energy balance subtracted energy losses from intake differed significantly (p0.05) except between group I and II, and the energy in group III and IV was retained at level of 4.2 and 80.2 KJ/kgW(0.75). It was concluded that supplementing concentrate to rye silage had an obvious effect on nutritive value of feed and nitrogen and energy balance in goats thus, up to 0.5% of body weight would be necessary for maintenance when goats fed rye silage