Caroço de algodao para vacas leiteiras. 2. Efeito na digestao total e parcial dos nutrientes, taxa de passagem da digesta ruminal e degradaçao da matéria seca e proteína bruta

An experiment was carried out to evaluate the effects of adding cottonseed (CS) to the ration on the total, ruminal and intestinal apparent digestibilities of the dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), ether extract (EE) and total carbohydrates (CHO), the rate of ruminal digesta passage and DM and CP in situ degradabilities. Four ruminally- and abomasally-fistulated 7/8 Holstein x Zebu cows was used in a 4 x 4 latin square design. The rations were composed of corn silage ad libitum and by four concentrate rations with different levels (0, 10, 20 and 30) of CS. The addition of CS to the ration affected only the NDF ruminal digestibility, which showed a quadratic effect, and the ruminal and intestinal digestibilities of CHO followed a square root model. The rate of ruminal digesta passage varied from 4.2 to 5.6 percent/h. For the rates of passage obtained in each ration, the average values for the four rations had effective degradabilities of DM and CP of 44.6 and 61.3 percent, respectively, for corn silage and 30.5 and 45.9 percent for CS. It was concluded that adding up to 30 percent CS to the concentrate ration may influence the NDF digestibility.