Effect of urea treatment and/or supplementation on the feeding value of rice straw for sheep

A 4 x 4 Latin Square Design experiment with four mature sheep (22.0-28.8 kg) was conducted to determine the effects of urea treatment and urea-molasses supplementation on the voluntary intake and digestibility of rice straw. The following treatments were tested: (1) untreated rice straw (RS), (2) urea treated rice straw (UTRS), (3) urea-molasses sprayed rice straw (UMSRS), and (4) urea molasses plus rice straw (UM+RS). The UTRS was prepared by spraying 4% urea solution onto rice straw at the rate of 1:1 (V/W) and kept in a polyethylene bag under an air tight condition for seven days. UMSRS was prepared by dissolving 1.5% urea and 7.5% molasses in water and was sprayed onto rice straw at the rate of 1:1 (V/W). The preparation of urea molasses mixture was maintained at the rate as in UMRS except that water was not added. All experimental animals were given a concentrate mixture of rice bran, copra meal, salt, and bone meal at equivalent to 1% of their liveweight. UMSRS and UM+RS rations had significantly higher nitrogen content than RS and UTRS. However, UTRS resulted in significantly lower lignin content than the other treatments. Hence, improved apparent digestibility coefficients for DM, CF, NFE, OM [dry matter, crude fiber, nitrogen free extract, organic matter] and cellulose were found in sheep given UTRS rations compared to those receiving RS and UM+RS diets. Evidently urea treatment improved the utilization of nutrients in rice straw. In this study, the CP [crude protein] content of RS was 6.81% which is comparably higher than the normal value of about 4%. All animals were able to maintain positive N-balance and had similar dry matter intake. The in vivo and in vitro DM digestibility of UMSRS is similar to that of UFRS but better than UM+RS. This result may be due to an improvement of the rumen condition when urea molasses was ingested simultaneously with the roughage