Qualitative evaluation of four subtropical grasses as standing hay: diet selection, rumen fermentation and partial digestibility by sheep

Abstract

The nutritive value of four subtropical grasses (Panicum maximum, Anthephora pubescens, Digitaria eriantha and Chloris gayana) standing hay were compared in terms of qualitative intake and partial digestibility by sheep. The species differed significantly in terms of diet  quality selected by sheep grazing the standing hay. The rumen  ammonia nitrogen (NH₃-N), total volatile fatty acid and propionic acid concentrations of sheep grazing P. maximum and A. pubescens were higher than those sheep grazing D. eriantha and C. gayana standing  hay. Organic matter intake (OMI) (g kg^–1 W^0.75 d^–1), nitrogen intake (g d^–1), digesta flow, the total N flow, NH₃-N flow, non-ammonia  nitrogen (NAN) flow and NAN disappearance (g d^–1) in the ileum were higher for sheep grazing P. maximum than for those grazing the other standing hays. The organic matter disappearance in the stomach and small intestine of sheep grazing P. maximum and D. eriantha standing hay was higher than for those sheep grazing either A. pubescens or C. gayana standing hay. The NAN flow/N intake were the highest for sheep grazing P. maximum and A. pubescens compared to C. gayana. The NAN digestibility was, however, not significantly different among  the four species. The standing hays (except for C. gayana) seemed to have the capacity to meet the N requirement of the sheep for production, but the OMI (g kg^–1 W^0.75 d^–1) was not sufficient to support maintenance requirement of the sheep.

African Journal of Range & Forage Science 2009, 26(2): 69–74