Orden et al., 2000. Asian-Aust. J. Anim. Sci., 13 (4): 490-496

In vivo digestibility, nitrogen retention and microbial protein yield from diets of 100% ammonia treated rice straw (ARS) (D1); 65% untreated rice straw (URS)+30% rice bran (RB)+5% SBM (D2) and 85% ARS+15% RB (D3) were determined using three Japanese Corriedale wethers in a 3x3 Latin Square Design. Results showed that DM consumption and organic matter digestibility were highest in D3; but did not promote high protein digestibility, which RB+SBM had effected in URS based-diet. Dry matter intake and OM digestibility were the same for D1 and D3. Solubility of fiber bonds was increased by ammoniation, resulting in higher NDF digestibility. Nitrogen retention and microbial protein yield of rice bran supplemented groups was higher than ARS, but supplementation did not significantly increase efficiency of microbial protein synthesis from ARS which did occur when RB+SBM was added to untreated straw. The quality of ammoniated rice straw could be improved through RB supplementation because of its positive effects on DM digestibility, nitrogen retention and microbial protein yield. However, the addition of RB+SBM to URS resulted to more efficient N utilization.