Intake, digestibility, nitrogen balance and certain rumen characteristics of Ethiopian Menz sheep fed teff straw supplemented with cotton seed cake, dry sesbania, dry leucaena or fresh leucaena
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Agroforestry Systems;31(3): 243-256
Permanent link to this item: http://hdl.handle.net/10568/28143
Twenty five rumen fistulated Ethiopian Menz sheep were used in a completely randomized block design to determine roughage utilization when different types of supplements (sesbania, leucaena, cotton seed cake (CSC) and forms (fresh or dry leucaena) were fed. The chemical composition, intake, digestibility, nitrogen balance and rumen degradibility coefficients were determined. Rumen PH and ammonia-nitrogen (NH3-N) levels were estimated in samples taken at 1, 2, 3, and 6 h after feeding. There was substitution of teff straw dry matter by the supplements. Fresh leucaena effected the highest substitution. Supplementation enhanced the dry matter degradation (DD) of teff straw at 6 and 12 hours of incubation but not for the other incubation times. There were no significant differences between treatments in the degradation constants: readly soluble component (a) slowly degradable fraction, (b) potential degradability and rate of degradation (C) and for rumen NH3-N concentration, the ranking was CSC > sesbania > dry leucaena> teff straw alone. The particularly high substitution rate observed with fresh leucaena might suggest that bulkiness may be a limiting factor in the intake of low quality roughages supplemented with tree leaves. The lower DM and OM digestibilities of the supplemented diets were attributed to substrate preference by rumen cellulolytic bacteria. Excessively high levels of rumen NH3-N (328 mg/1) in the CSC diet resulted in high urinary nitrogen losses leading to low N balance. This may suggest that for the utilization of poor quality tropical roughages, moderate levels of rumen NH3-N sustained over a longer period may be needed.