Feeding behavior of dairy cows fed different levels of castor meal in the diet

Resumo

This study aimed to evaluate the inclusion of castor meal in the diet of lactating cows in grazing system and its implications in feeding behavior. Eight Holstein x Zebu crossbred cows, with average milk production adjusted to 300 days in the previous lactation, between 5000 and 6000 kg and 100.33 ± 13.33 days of lactation and average body weight of 509.47 ± 61.90 kg, were distributed in two 4 x 4 Latin squares, with 4 levels of castor meal inclusion in the total diet, and using Brachiaria brizantha pasture as roughage. The experiment consisted of four experimental periods, lasting 21 days each. In each trial, the roughage and supplements were collected for evaluation of chemical composition. Animals were subjected to visual observation for evaluation of feeding behavior for 24 hours, from the 20th to the 21st day of each experimental period. The observations of the activities were recorded every five minutes. We determined the number of ruminating chews and the time spent in rumination of each ruminal bolus with the use of digital stopwatch. There was a quadratic effect for the grazing time with maximum point of inclusion of castor meal at 4.61% in the diet; other variables did not differ: rumination, idleness, trough, rumination efficiency, feeding and grazing time, rumination and idleness. Castor meal can be included in the diet with levels up to 10%, for little changes in the feeding behavior of animals.