Associations between milk intake and activity in the first days of a calf's life and later growth and health

We examined whether calves’ milk intake and activity in the days after birth predict later growth and the risk of illness. Female Holstein calves (n=130) were housed in individual pens where they were allowed ad libitum milk from birth to 5 days of age. Daily milk intakes were recorded and accelerometers attached to the calves measured time spent standing and lying down. After 5 days, calves were housed in group pens with four to nine calves per group and allowed 12L/day of milk and ad libitum hay and starter from automated feeders. Calves were weighed at birth (birth weight=BW) and at 28 days of age and health status was determined daily. Digestible energy (DE) intakes were calculated from feed intakes. During days 2–4, there were large differences among calves in the amount of milk consumed, which ranged from 7.3% BW/day (2.4L/day) to 30.5% BW/day (12L/day) with a median of 16.3% BW/day (6.7L/day). Twenty-one calves were treated for illness from days 6 to 28. These calves had lower milk intakes on days 2, 3 and 4 than calves that remained healthy (P<0.05). For the calves that did not become ill, milk intake on day 4 was correlated (r=0.29; P<0.01) with ADG from days 0 to 28 and correlated (r=0.33; P=0.03) with the residual body weight on day 28 (when birth weight and digestible energy intakes from days 5 to 28 were accounted for using multiple regression). Time spent standing from days 2 to 4 varied between calves but was not correlated with BW, milk intake during days 2–4, or weight gains to day 28 (P>0.10). Very young calves can drink large quantities of milk, and the calves that drink the largest amounts in the first days of life have greater long-term growth rates and are less likely to become ill. Milk intake may be a better sign of early calf vigour than activity levels.