Calves' behaviour during nursing is affected by feeding motivation and milk availability

We examined the relationship between calves' suckling behaviour at nursing, calves' feeding motivation and milk availability. Dairy calves (six female and four male) suckled from their dams twice a day after milking from birth until 9 weeks old. By removing different amounts of milk from the udder during the milking prior to the nursing, we were able to control how much milk was available to the calf during nursing. Reducing milk availability led to lower milk ingestion but a longer duration of sucking in more frequent but shorter bouts and more butting and switching between teats. Increasing milk availability had the opposite effects although no extra milk was drunk compared to the control condition. By use of tube feeding or reducing the amount drunk during a previous meal, we were able to control the level of the calves' feeding motivation at the nursing. Increasing the calves' feeding motivation increased the duration of sucking and increased the amount of milk consumed by the calf. Reducing the calves' hunger had the opposite effects. Calves' suckling behaviour did not change between the ages of 2 and 9 weeks. The rate of sucking was not affected by either milk availability of feeding motivation. The results show that calves' behaviour during nursing is a poor indicator of milk transfer but that calves are able to regulate milk intake during nursing. Butting and teat switching are likely signs of low milk flow rates. Allowing calves to nurse milked cows occasionally is a useful model to examine the effect of feeding motivation and milk availability on suckling behaviour.