Play behaviour in dairy calves is reduced by weaning and by a low energy intake

We examined the effects of milk allowance and weaning on the duration of play running in group-housed dairy calves. Our predictions were that (1) calves on a lower milk allowance would run less than calves on a higher allowance; and (2) running would decrease at weaning, especially in calves weaned earlier rather than later. Milk allowance and age of weaning were varied across three treatments: ‘6L-early weaned’ (fed 6 L/d of milk and weaned at 7 weeks of age), ‘12L-early weaned’ (fed 12 L/d of milk and weaned at 7 weeks), and ‘12L-later weaned’ (fed 12 L/d of milk and weaned at 13 weeks). Weaning occurred gradually over 9 days. Calves were observed for 2 days at each of six ages (3, 5, 7, 9, 11 and 13 weeks) and their average daily duration of running at each age was calculated. At 3 weeks, the 6L-early weaned calves ran less than calves receiving 12 L/d of milk (P < 0.01), but by 5 weeks there were no differences among treatments (P = 0.52). All treatments showed a drop in running at weaning but the decrease was more pronounced in the early-weaned calves (both Ps < 0.001) than in the later-weaned calves (P = 0.06). At 3 weeks (before weaning) and at 7 and 13 weeks (immediately after weaning), there were positive correlations between digestible energy intake and duration of running (r = 0.48, 0.56, and 0.29, respectively, all Ps < 0.05). Overall, our results show that running by calves is reduced by a low milk allowance and by weaning off milk, and they suggest that play behaviour may be a useful measure of how the welfare of calves is affected by feeding practices.