Dry matter degradation of the leaves of eleven mulberry varieties in the rumen of cattle and changes during the grazing season

摘要

The dry matter (DM) degradation and its seasonal changes in eleven mulberry varieties were determined using the nylon bag technique. The leaves were harvested on 6 July, 25 August and 23 October. Degradability was measured by incubating samples in the rumen of two fislulated Holstein cows For 4, 8, 12, 24, 36, 48 and 96 h. The degradability of the readily soluble fraction (a) ranged between 6.9-34.4 percent in July, 27.2-49.6 percent in August, and 33.6-44.5 percent in October. The corresponding values for the slowly degradable fraction (6) were 61.5-87.0, 44.7-67.6 and 53.5-63.2 percent, respectively. The potential degradability (PD = a + b) and rate of degradation of b per h (c) ranged between 91.1-97.2 percent and 8-16 percent/h, respectively and were not significantly affected by time of harvesting and varieties. Both factors significantly affected effective degradability, which was 79.2, 81.9 and 84.8 percent in July, August and October, respectively, and varied between 75.0-89.5 percent among the varieties. The results of this study suggested the existence of varietal differences in degradability among the mulberry varieties. However, the leaves of all the mulberry varieties tested were highly degradable and therefore can serve as suitablesupplements to low quality basal grass diets.