Fill effect of concentrates in the rumen of sheep

Abstract

In an experiment based on a 4 × 4 latin square design with eight sheep, of which four were fistulated, the effects of four diets (H: hay alone; HB: hay + barley; HW: hay + wheat; HP: hay + beet pulp) were studied on daily dry matter (DM) intake, rumen content and the physicochemical characteristics of rumen content. The supplies of 700 g of concentrate were equivalent, on average, to 32% of total DM intake of the diets. Intake of hay alone was 66 g/kgW0.75 and the rates of substitution of roughage by concentrate were 0.48, 0.42 and 0.63 for diets HB, HW and HP, respectively. At the end of the main meal, fresh digesta contents in the rumen were the same with all the diets, consistent with a physical effect on intake. The estimated residence times of the digestive residues of the concentrates were 8, 4 and 9 h, with the value for barley probably including an increase in residues from hay. At the end of the night, rumen fill tended to be lower when animals were receiving concentrates; thus, digestive residues of concentrates may not have limited intake between large meals.