Editor’s note: This article was written by Coleen Jones, research associate, and Jud Heinrichs, professor of dairy and animal science at Penn State, and originally appeared in the June 2010 Penn State Dairy Digest.
In a recently published study, heifers fed whole milk before weaning produced more milk during their first lactation than those fed milk replacer as calves. Israeli researchers published these results in the June issue of the Journal of Dairy Science.
Forty-six Israeli Holstein calves were allowed to consume as much fresh whole milk or milk replacer as they would drink during two 30-minute feeding periods each day. Free-choice water and starter were also provided. Gradual weaning began at 51 days of age and was completed at 60 days of age. All calves received the same feed from 60 through 150 days of age, at which time half of the heifers were assigned to a growing heifer ration and the other half received the growing heifer ration with an additional 2 percent protein supplemented. These rations were fed through 320 days of age. From 320 days of age through calving and throughout the first lactation, all heifers received the same ration. Body composition at 60 days and 300 days was measured using an additional 12 heifers that were fed and managed identically to those in the lactation experiment.
Calves fed milk replacer drank 2.58 gallons per day (2.62 pounds dry matter) compared to 2.37 gallons (2.40 pounds dry matter) for calves fed whole milk. There was no difference in starter intake, which averaged 0.4 pounds per day. However, calves fed whole milk weighed about 7 pounds more at weaning (189 pounds versus 182 pounds), had nearly 10 percent higher average daily gain (1.78 pounds versus 1.62 pounds per day), and were more efficient at converting feed to body weight gain. Height was similar between the groups at weaning and averaged 33.6 inches at the withers and 35.4 inches at the hips. Calves consumed similar amounts of metabolizable energy, but whole milk-fed calves had higher protein intake due to the composition of whole milk (29.4 percent fat, 25.9 percent protein) compared to milk replacer (13 percent fat, 23.7 percent protein).
Analysis of body composition at weaning showed that calves fed whole milk stored more body fat than calves fed milk replacer. The total fat mass in calves fed whole milk was 1.78 times that in calves fed milk replacer. Total fat as a percentage of empty body weight was 1.56 percent for whole milk calves and 0.96 for those fed milk replacer. By 300 days of age, weight of kidney and mammary pad fat was similar between the two groups.