Abstract
An experiment was conducted in semi-arid Niger to determine the influence of supplementation with groundnut cake (GC) [0 g kg-1, 2.5 g kg-1, 5 g kg-1, and 7.5 g kg-1 live weight (LW)] and P (0 g day-1 and 3 g day-1 animal-1) on diet and millet stover intake and digestibility, sheep growth rate, and nutrient excretion. Total digestible organic matter intake (DOMI, g kg-1 LW0.75) increased 4.24 ± 1.26 g g-1 of GC and decreased -0.31 ± 0.16 g g-1 GC2, and increased (P = 0.10) with P supplementation. Millet stover intake (g kg-1 LW) was related to GC level by both linear (1.79 ± 0.53 g g-1 GC) and quadratic (-0.20 ± 0.07 g g-1 GC2) functions and to P supplementation by linear function (0.87 ± 0.46 g g-1 P). No effect of GC x P interaction was observed. At equal level of GC, P supplementation increased stover intake by 2-20%. Diet digestibility increased linearly (P < 0.01) with GC level, but no effect of P supplementation was observed. Digestibility of neutral detergent fibre was unaffected by either GC or P level. Animals supplemented with P had adequate P (0.24%) in their diet in contrast with those unsupplemented (0.05-0.18%). Live weight gain (g day-1) increased 22.10 ± 3.10 g g-1 GC and decreased -1.52 ± 0.39 g GC2. Live weight gain response to P supplementation (7.33 ± and 1.66 g g-1 of P) was independent of GC level. Nitrogen concentration in faeces [g kg-1 faeces dry matter (FDM)] increased linearly both by GC and P supplementation, whereas urinary N (g L-1) was only influenced by GC level. Faecal P (g kg-1 FDM) increased about three-fold with P supplementation. It is concluded that an adequate capture of the additional N and P that is voided following supplementation, could enhance the sustainability of mixed farming systems in the Sahel.
