RUMEN DEGRADABILITY OF THE UPPER AND LOWER PARTS OF UNTREATED OR UREA TREATED RICE STRAW VARIETIES

Abstract

A study to evaluate the digestibility of the upper and lower parts of rice straw varieties and the effect of urea treatment was conducted using a rumen degradability (in sacco) study. Straw from four varieties of rice (Dong, llb, Yrl and Yrm) were separated in upper and lower parts and were treated with 4% urea. The degradation characteristics of the straw were measured by incubating samples (in nylon bag) for 8, l6, 48 or 72 hours in the rumen of four sheep fitted with nrmen cannulae. The data were described using exponential equation p= a+b (l-e'°t), where p=degradation loss, t=time, and a,b and c are constants. Dry matter degradability of the lower part was higher than the upper part for all varieties except for llb, Urea treatment improved the rumen degradability of rice straw, where the rate of degradation constant (c) of urea treated straw was significantly higher (P<.05) than untreated straw (0.045 vs 0.031 fraction/hour) and potential degradability (PD) of urea treated straw was significantly higher than untreated straw (632 vs 568 g/kg DM).