SUPPLEMENTATION OF MAIZE STOVER FOR ETHIOPIAN MENZ SHEEP - EFFECTS OFCOTTONSEED, NOUG (GUIZOTIA-ABYSSINICA) OR SUNFLOWER CAKE WITH OR WITHOUT MAIZE ON THE INTAKE, GROWTH, APPARENT DIGESTIBILITY, NITROGEN-BALANCE AND EXCRETION OF PURINE DERIVATIVES

Thirty-six male Ethiopian Menz sheep (9 to 12 months old, average live weight 15.8 (s.d. 1.84) kg), given maize stover (1.5 times ad libitum ) supplemented with either 75 g cottonseed cake (CSC), 114 g noug cake (NGC; Guizotia abyssinica) or 112 g sunflower cake (SFC) with or with out maize grain, were used in an 88-day study comprising growth and ba lance trials. The trials were undertaken according to a randomized-blo ck design with a 2 X 3 factorial arrangement. There were no significan t interactions (P > 0.05). Sheep consumed significantly more stover wh en supplemented with CSC compared with NGC and SFC (P < 0.05). Maize g rain significantly increased organic matter intake (P < 0-001). Althou gh CSC tended to support lower live-weight gains, the effect of protei n was not significant. Maize grain increased live-weight gains (P < 0. 01). Urinary nitrogen (N) excretions were similar between CSC and SFC but about 0.22 higher with NGC (P > 0.05). The faecal N output was 0.3 3 (P < 0.01) and 0.18 (P < 0.05) higher with CSC than with NGC and SFC respectively. Maize grain had no effect on any of the N-balance measu rements. Cottonseed cake supported lower daily production of purine de rivatives (PD) (P < 0.01), microbial purine (P < 0.01) and microbial p rotein (P < 0.01) than either NGC or SFC. Maize grain increased the da ily excretion of total PD (P < 0.05), microbial purine (P < 0.05) and microbial protein (P < 0.05). Neither the protein source nor maize gra in affected the efficiency of microbial protein synthesis. It was conc luded that SFC was utilized more effectively both in terms of rumen mi crobial N synthesis, N retention and growth. The addition of a small a mount of energy as crushed maize grain increased microbial N synthesis , N retention and live-weight gain.