Weaning and separation in two steps—A way to decrease stress in dairy calves suckled by foster cows

The aim of this study was to investigate whether the prevention of suckling and the separation from a foster cow in two steps lower the behavioural and physiological stress reaction in calves compared with if the two events occur simultaneously. Twelve groups, each consisting of one cow and four calves, were formed when the calves were 1 week old, and the calves were prevented from suckling at 10 weeks of age. In six of the groups, the calves were prevented from suckling by simultaneous separation from the cow (control). In the other six groups, the calves were fitted with a nose-flap, which prevented them from suckling while they were kept together with the cow for another 2 weeks before they were separated at 12 weeks of age (two-step). The behaviour and the heart rate of the calves were recorded, and saliva cortisol samples were taken after the calves were prevented from suckling (both treatments), as well as after the two-step separation. The two-step calves vocalised and walked significantly less when prevented from suckling than control calves (p < 0.05), although no effect of treatment on the heart rate or cortisol was found. Calves in the two-step treatment sniffed the interior of the pen significantly less (p < 0.05), and directed less social behaviours towards other calves in the group (p < 0.01) than calves in the control treatment. At the time of separation, calves in the two-step group vocalise and walked significantly less (p < 0.01), and also had lower heart rates (p < 0.001) than the control calves. The cortisol levels decreased in the two-step group, whereas it increased in the control group as compared with baseline values (p < 0.05). We conclude that two-step weaning, when compared with the simultaneous weaning and separation, reduces the behavioural reaction both at weaning and separation and the physiological reaction at separation when dairy calves are weaned from foster cows.