the utilization by sheep of winter and spring Smuts finger and Kikuyu pastures

Abstract

An experiment was conducted on Smuts finger (Digitaria eriantha ssp. eriantha) and Kikuyu (Pennisetum clandestinum) pastures during a winter and spring period to study the effect of postruminal energy and/or protein supplementation on the selection pattern and performance of sheep. In a further experiment the digestion and utilization of these pastures were quantified. Voluntary intake on both pastures was not significantly affected by postruminal addition of casein but glucose tended to depress intake. In vitro digestibility of organic matter (IVDOM) and crude protein content of oesophageal samples were not significantly influenced by either casein or glucose. Consequently, it was concluded that postruminal amino acid and energy supply do not alter the quality of pasture selection but, depending on circumstances, the amount eaten may be affected. The amount of non‐ammonia nitrogen (NAN) in winter and spring samples flowing through the abomasum was proportional to the nitrogen (N) content in the grass organic matter (OM), while the volatile fatty acid (VFA) production was approximately associated with the digestible OM (DOM) intake. N retention on Smuts finger was significantly higher than on Kikuyu. One of the reasons appears to be less unavailable N in the cell wall of Smuts finger than in the cell wall of kikuyu grass.