2002 Volume 48 Issue 3 Pages 236-241
The effects of heat treatment of tropical grass and legume silages on the degradability of nitrogen in the rumen and the post-rumen digestive tract were evaluated. Tropical pasture legume species Phasey bean (Pb) and grass species Guinea grass (Gp) were ensiled. Four three-day heat treatments of 20, 40, 60 and 80℃ were conducted before opening the silos. The nitrogen degradation patterns of heat-treated silages in the rumen were measured by the nylon bag technique using two rumen-fistulated Holstein dry cows. After 24 hours, the residual protein was digested with pepsin-pancreatin solution to separate the degradable and undegradable nitrogen in the post-rumen digestive tracts. The results obtained were as follows : 1. The effective nitrogen degradability of Gp was higher than Pb, whose values have been shown to decrease with increasing heat temperature. 2. The ADF insoluble nitrogen was partially degradable in the post-rumen digestive tracts, even if treated with higher temperature. 3. It has been to shown that the degradable nitrogen ratio in the post-rumen digestive tracts tended to decrease by heat-treatment and the ratio of undegradable nitrogen in all digestive tracts tended to increase by heat-treatment.
