The increase in the production of P-microbial 100 g-1 of MO degraded may have occurred due to a reduction in protozoa in the rumen (Kozloski 2011) caused by increased soybean meal in the diet, which resulted in an increase in EE supply (Table I and II); this increase may cause defaunation of protozoa (Martinele et al. 2008), resulting in further development of ruminal bacteria.