Development of Rumination in the Young Calf

The activities of 12 Jersey and 14 Holstein calves, with special attention to rumination, were observed for a full day's time each 2 wk. from 1-2 to 15-16 wk. of age. Rumination had begun in ]8 of the calves in the first 2 wk., 25 in the second 2 wk., and in all calves in subsequent periods. Rumination time increased rapidly to an average of nearly 5 hr. per day at 6-8 wk. of age. Thereafter, the rate of increase in rumination time was reduced. Rumination time was positively correlated with dry feed consumption, but less time per pound of feed was spent ruminating as the calves aged. The appearance of rumen contents of 17 calves sacrificed at 12-22 days of age indicated that more than half of the calves were ruminating effectively at 2 wk. of age. Observations are also presented of the times spent eating and drinking and lying down, as well as correlations between blood glucose content and rumination time.