INTAKE, RUMEN VOLUME, RETENTION TIME AND DIGESTIBILITY OF DIETS BASEDON POULTRY LITTER AND WHEAT-STRAW IN BEEF-COWS BEFORE AND AFTER CALVING

Beef cows in the 14 weeks before calving and during the first 12 weeks after calving were fed one of three diets based on 15, 30 and 45 % br oilers poultry litter (PL), 20 % maize grain (MG) and 65, 50 and 35 % wheat straw (WS) on a DM basis, respectively. They were housed from Ju ne to November in individual open pens. Four weeks before and 9 weeks after calving, in vivo digestibility, fibre and fluid mean retention t ime (MRT) were measured. The intake of all diets before calving was lo w. Nine weeks after calving the intake of DM increased 2.1 times on th e 15 % PL diet, and 1.6 times on the two other diets. The in vivo dige stibility of the 15 % PL diets was lower than that of the two other di ets before calving, and increased after calving, in spite of the doubl ing of its intake, while that of the 45 % PL diet decreased. The mean retention time of fibre in the digestive tract was not affected by the increase in DM intake after calving on the 15 % PL diet and was short ened on the two other diets. It seems that the combination of the volu me taken up by the gravid uterus and the bulkiness of the 15 % PL diet s (65 % WS) reduced the intake and impaired the digestibility of that diet before calving. After calving, the fibre pool increased considera bly and consequently both intake and digestibility were increased.