Digestion and Rumen Metabolism of Forages by Red Deer, Goats and Sheep

Digestive efficiency was compared in Red deer, goats and sheep fed chaffed lucerne hay (Experiment 1), Goats digested fibre more efficiently than sheep and had the greatest rate of rumen ammonia production, Red deer showed the capacity to increase VFI from winter (W) to summer (S) without depressing apparent digestibility, through slowing the rate of rumen particulate outflow. Fractional outflow rate (FOR) of water from the rumen and the ratio FOR water/ FOR particulate matter were both considerably greater for deer than for sheep and goats. It was concluded that this would enable deer to digest soluble ration components more efficiently while allowing effective selective retention of fibre, and explains the absence of rumen bloat when deer are fed red clover (RC). The lower rumen FOR and greater fibre digestibility in deer-fed RC compared with perennial ryegrass-based pasture (Experiment 2) suggests that the higher VFI found for RC in the field is due to more rapid disintegration of plant components in the rumen rather than to increased rumen outflow rate.