Cross-sucking and other oral behaviours in calves, and their relation to cow suckling and food provision

Abnormal oral behaviour in calves is believed to develop when there is a lack of opportunity to suckle, but it is unclear whether they need access to their mother or whether a multiple suckling system will suffice to prevent this behaviour from developing. Therefore, in an initial experiment, the behaviour of calves that suckled their own mother or another cow for 15 min each day was compared with that of artificially-reared calves which had no opportunity to suckle. Cows were mechanically milked twice daily, after which they were either suckled for 15 min by their own calf (Treatment O), multiple-suckled by other cows’ calves (Treatment M) or unsuckled with the calves reared artificially (Treatment A). There was no difference between treatments in the time that calves spent consuming milk, but suckling calves consumed less milk than those reared artificially. The incidence of cross-sucking was greater for non-suckled calves (1.8 events/day) than for suckled calves (0.33 events/day, with no difference between Treatments O and M). In the non-suckled calves, cross-sucking was at its highest frequency 1 min after the end of milk-feeding and declined linearly to negligible levels at 13 min post-milk feeding. For calves in this treatment, most (78%) of the cross-sucking was directed at the inguinal region (especially the udder or scrotum) of other calves, whereas in suckled calves, most of the cross-sucking (81%) was directed at the mouths of other calves. The time spent consuming concentrate feed, and the amount of feed consumed, was greater for artificially-reared calves, compared with suckled calves, suggesting that food ingestion could provide a replacement stimulus. In a second experiment, it was observed that before weaning, the time that calves spent licking their pen or bucket increased until feed intake was sufficient to stimulate significant amounts of rumination, after which it declined. It is concluded that cross-sucking of artificially-reared calves, which is derived from motivation to perform sucking in the inguinal region, can be prevented by providing short access to either the calf’s dam or another cow for two short periods each day. In the absence of a cow to suckle, the calves lick inanimate objects repeatedly until the consumption of solid food stimulates rumination.