Chemical Composition and In Vitro Digestibility of Forage Consumed by Goats on Lightly and Heavily Stocked Ranges1

Abstract

CHEMICAL composition and in vitro digestibility of forages consumed by Angora goats were compared on heavily-stocked, fair-condition range and lightly-stocked, good-condition range in the Edwards Plateau region of Texas. Chemical composition and in vitro digestibility varied greatly from season to season but general trends were similar for the two ranges for a particular nutritional attribute. When statistical differences did occur, forage on the lightly stocked range was higher in crude protein, cell wall constituents, cellulose and lignin but was lower in hemicellulose content and in vitro digestibility than that on the heavily stocked range. Observed differences in nutritional quality were not of sufficient magnitude or duration to explain a 5.1 kg difference in average weight gain and a 0.7 kg difference in mohair yield of intact animals grazing the two ranges. The production deficiency of animals on the heavily-stocked, fair-condition treatment was therefore attributed to a restricted forage intake, imposed largely by a shortage of palatable forage plants.