This study examined the behavioural responses of dairy cows and their calves when the calf is separated from the cow 6 h, 1 or 4 days after birth. The behaviour was documented by video recordings starting an hour prior to separation and ended 21 hours after the separation occurred. Prior to separation, the younger calves tended to make more calls, move around the pen and stand more than older calves. As for the cow, prior to separation, the cows with younger calves would move around the pen more and she would also vocalize more. After separation, the older the calf was at separation, the greater amount of time it spent moving around the pen, standing, and standing with its head out of the pen. The cow’s behaviour at separation followed a similar trend as the calves. Cows weaned from their young four days after birth vocalized four times more than cows separated at one day or 6 hours. Along with a higher rate of vocalization, the vocalizations of cows that spent more time with their young after birth were also higher in fundamental frequency and a lower emphasized harmonic. Calves that spent more time with the cow after birth were on treatment for scouring for fewer days. There were no significant interaction between timing of separation and the cow’s milk production and calves’ weight gain. The intensity of the cow and calf’s reaction to separation increased with age in both the cow and calf. However, the negative behavioural response may be negated by the health advantages incurred by allowing the calf to remain with the cow for longer periods of time after birth.