Can the weaning stress of dairy calves be reduced by weaning later?
Dairy calves are increasingly being fed large volumes of milk (8-12L/d), which reduces feeding motivation and improves weight gain. However, they often lose weight when weaned off milk, even if weaning is gradual, due to low grain intake. We examined whether delaying the age at weaning would reduce the growth check at weaning. Calves were raised in groups of 9 and fed milk and grain with automated feeders. In each group 3 calves were randomly assigned to one of 3 treatments: 1. low-milk early-weaned: fed 6l/d of milk and weaned at 42 days; 2. high-milk early-weaned: fed 12l/d of milk and weaned at 42 days: 3. high-milk late-weaned: fed 12l/d of milk and weaned at 84 days. Milk and grain intakes and feeder visits were recorded daily and body weight weekly. Animals were weaned gradually over a 10 day period. The high-milk late-weaned calves continued to drink 10-12L/d up to the day of weaning. During the 10d weaning period, the low-milk early-weaned calves made many more visits (PROC MIXED: P<0.001) to the milk feeder (23.9±0.9/d) than the high-fed early weaned (15.8±0.9/d) and high-fed late weaned calves (17.1±0.9/d), which did not differ (P>0.10). Grain intake during the weaning period was highest for high-milk late-weaned calves (1.10±0.08kg/d), intermediate for low-milk early-weaned calves (0.77±0.08kg/d) and lowest for high-milk early-weaned calves (0.36±0.08kg/d) (P<0.01). Weight gain during weaning followed the same direction (8.8kg vs 5.1kg vs 3.8kg ±0.2kg) (P<0.01). At 15weeks of age, high-milk late-weaned calves were heavier (155.0±1.4kg) (P<0.01) than high-milk early-weaned calves (145.7±1.4kg) and low-milk early-weaned calves (142.8±1.4kg), which did not differ (P>0.10). Delaying the age at which calves are weaned off milk keeps the advantages of feeding them more milk by increasing their ability to eat grain. However, it does not reduce their motivation to drink milk while being weaned.