Because the survival of young mammals depends on sucking success, it is assumed that sucking motivation must be strong and that sucking deprivation would result in frustration, which could have a negative impact on the animals' welfare. This concern, as well as that regarding cross-sucking between calves and intersucking between older animals, has stimulated research on the motivation of calves for non-nutritive sucking. Non-nutritive sucking is elicited by the ingestion of milk; and the lactose concentration in milk, rather than fat or protein, is the main factor that stimulates it. Every time a calf drinks milk, it is stimulated to suck, and deprivation of sucking may interfere with digestive processes or satiety. To understand calf behaviour during nutritive sucking, the effects of milk flow on calves' sucking and butting were examined in an artificial feeding system. Slowing down and stopping the flow rate stimulated butting and potentially lengthened the duration of sucking for the meal. It also stimulated the calf to switch teats when a second teat was available. These findings are well correlated to observations of the calf suckling a cow in experimental manipulations. The duration of the meal was not correlated with milk intake, but it was influenced by milk availability and how hungry the calf was. Furthermore, calves were observed to butt more often when there was less milk available in the dam's udder, presumably because milk flow is slower. Consequently, it is the occurrence of butting rather than sucking duration that would be a good indicator of milk intake when the calf is suckling the dam. Based on these observations, a combination of slower milk flow and hay feeding and the provision of a non-nutritive artificial teat to reduce the occurrence of cross-sucking following a milk meal are recommended.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, P.O. Box 90-2000, Route 108 East, Lennoxville, Que. J1M 1Z3, Canada.|
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