1. Twenty spring-born Friesian calves, housed indoors, were divided into two groups each of 10 calves. During their first three weeks all calves were fed alike on whole milk containing 3·5% butterfat. At three weeks of age calves in one group were changed to a diet consisting of reconstituted buttermilk powder which was made up to the same energy content as the milk. Up to the 30th day intake was gradually increased to 20% of body weight; thereafter till slaughter of the calves at approximately 200 1b. live-weight both groups were fed to appetite twice daily.
2. Calves in both groups grew well and differences between groups in growth rate, and age at slaughter, food consumption and food conversion, were all statistically non-significant.