Caroço de algodao para vacas leiteiras. 3. Efeito na eficiência microbiana, concentraçao de amônia e pH ruminais

An experiment was carried out to evaluate the effects of adding cottonseed (CS) to the ration on rumen microbial efficiency, ammonia concentration and pH. Four 7/8 Holstein x Zebu cows, ruminally and abomasally-fistulated, were used in a 4 x 4 latin square design. The rations employed were composed of corn silage ad libitum, and four concentrate rations different levels of CS (0, 10, 20 and 30). The addition of CS to the ration did not affect the microbial efficiency, which, on the average, was 0.44 g of bacterial dry matter/g, in average, of digested carbohydrate in the rumen. Rumen pH varied from 5.5 to 7.0 and showed the minimum values of 5.7, 5.5, 5.6 and 5.8, respectively, for the rations R0, R10, R20 and R30. The maximum ammonia concentrations in the rumen were 14.0, 13.1, 12.7 and 12.7 mg N - NH3/100 ml, respectively, for rations R0, R10, R20 and 30. It was concluded that adding up 30 percent, CS to the concentrate ration did not affect microbial growth.