Effects of early separation on the dairy cow and calf 1. Separation at 6 h, 1 day and 4 days after birth

The aim of this study was to evaluate the effects of age of separation on t he behavioural responses of the dairy calf and cow. Calves were separated f rom their dams 6 h, 1 day, or 4 days after birth (n = 9 cow-calf pairs in e ach of the 3 treatment groups) and behaviour was video and audio taped from 1 h before separation to 21 h after separation. In the hour immediately be fore separation, we found that the younger calves tended to call and move m ore in the pen, and spent more time standing than the older calves, but aft er separation these trends reversed. Calves separated at older ages made si gnificantly more movements in the pen (P < 0.05), spent more time standing (P < 0.05) and spent more time with the head out of the pen (P < 0.01) than calves separated soon after birth. We observed a similar pattern for the c ows. Before separation, cows with younger calves moved more frequently abou t the pen (P < 0.05), and called at much higher rates (a mean of 40.7 calls during 40 min for cows on the 6-h treatment, vs. 0.2 calls for cows in the 4-day group; P < 0.001). After separation, cows in the 4-day group called at approximately four times the rate of those separated at 6 h or 1 day (P < 0.01). Moreover, the calls produced by cows separated later had a signifi cantly higher fundamental frequency (P < 0.001) and a lower emphasized harm onic (P < 0.02) than the calls of cows separated from calves soon after bir th. There was no difference between treatment groups in the other behaviour al measures, either before or after separation. Calves separated at older a ges tended to require fewer days of treatment for scouring, but calf weight gain and cow milk production did not differ among treatment groups, In con clusion, behavioural responses of both the cow and calf increase in relatio n to calf age at separation. However, there may be health advantages associ ated with delayed separation that compensate for the increased behavioural response. (C) 2000 EIsevier Science B.V. All rights reserved.