The effects of diet supplements and gamma irradiation on dissimilation of low-quality roughages by ruminants: I. Studies on the terylene-bag technique and effects of supplementation of base ration

Abstract

SUMMARYThe terylene-bag technique was evaluated as a means of establishing the rate of intra-ruminal degradation of the following test materials: nassella (Nassella trichotoma), wire grass (Aristidasp.), rice straw, lucerne chaff and cotton lint. The tests were made in sheep fed base rations of lucerne chaff, wire grass and rice straw at different levels of intake. Values established by this technique are of acceptable repeatability and provided a more responsive indicator of intraruminal degradation rates of the test materials than did base diet apparent digestibility.Supplementation with casein, urea and sucrose did not significantly alter voluntary feed intake of sheep fed rice straw. Supplementation had no statistically significant effects on apparent digestibility of the base diet of rice straw, but had significant effects upon the rate of degradation of test materials suspended in the reticulo-rumen in terylene bags for 72 h.Results are presented which indicate that casein supplementation of rice-straw-fed sheep enhanced ruminal production of trace VFA's (butyric, iso-butyric, iso-valeric and valeric). Urea supplementation did not lead to statistically significant increases in VFA concentration or proportion of individual acids in rumen liquor, with the exception of valeric acid.