In this study, although the values of g P-microbial 100 g-1 of MO degraded in the rumen increased as WCSEd increased, they were within the range of variation described by Pathak (2008), who reported that the efficiency of microbial synthesis can range from 13 to 17.6 g P-microbial 100 g-1 of MO degraded in the rumen.