Abstract
Nine Toggenburg × Saanen wether kids, weight 27 ± 3 kg and age 3 mo, and nine Suffolk × Barbados wether lambs, 45 ± 4 kg and 5 mo, were offered complete diets with 35, 50 and 65% wheat straw (WS) at ad libitum intake in a split-plot design. Voluntary dry matter (DM) intake per kg body weight (BW) was higher (P<.01) for goats; however, intakes were not different for the two species when expressed per unit of BW·75. Digestibility of DM, estimated by total fecal collection, did not differ significantly between species, but was higher for sheep (57%) than for goats (52%) for the 65% WS diet. Digestibility of neutral detergent fiber (NDF), acid detergent fiber, cellulose and permanganate lignin was higher (P<.01) in sheep than in goats, with the greatest difference noted for the 65% WS diet. Total DM intake per BW·75 was correlated (P<.01) with the percentage of fecally recovered lignin in the diet (r = −.58) and with fecally recovered NDF (r = −.45 and −.52 for goats and sheep). Rumen pH was higher (P<.05), ruminal osmotic pressure was lower (P<.01), molar concentration of propionic acid was lower (P<.05) and molar concentration of butyric acid was higher (P<.01) in the sheep than in the goats. The species difference was not significant for ruminal molar concentration of acetic acid. The data taken as a whole support the hypothesis of a relatively higher DM intake and lower fiber digestibility by goats than sheep, when their diet has a relatively high fiber concentration. Copyright © 1985. American Society of Animal Science . Copyright 1985 by American Society of Animal Science