EFFECTS OF COLD EXPOSURE AND PLANT SPECIES ON FORAGE INTAKE, CHEWING BEHAVIOR AND DIGESTA PARTICLE SIZE IN SHEEP

Abstract

Three closely shorn sheep were allotted to each of three diets of chopped hay prepared from red clover, reed canarygrass and bromegrass, respectively. The animals were housed at 25, 10 and −5 °C during three periods of 28 days. For the final 8 days of each period, each individual sheep was restricted to 90% of its voluntary feed consumption and hay was given at intervals of 2 h. Eating and chewing behavior, rumen fluid kinetics and digesta particle size were determined. Voluntary intake of clover hay was greater, but chews during eating and rumination were less than for sheep consuming grass hay. The small particle fractions present in the duodenum and rumination activity were greater in the sheep fed grasses. Feed intake, rumination chews and duration, and digesta particle size in the duodenum were increased in sheep housed at −5 °C. Eating duration and chews, particle size of rumen digesta and rumen fluid volume were not affected by cold stress, but fluid retention time was reduced, while daily fluid flow from the rumen tended to increase. Key words: Forage intake, cold stress, chewing behavior, digesta particle size, fluid passage