Growth and feed conversion of Jersey and Friesian bulls in relation to plane of nutrition

Abstract

Sixty Jersey and 48 Friesian bull calves were reared from birth on either of two planes of nutrition. A milk replacer and a concentrate diet were given before and after weaning respectively. The Jerseys were weaned at 45 kg and the Friesians at 77 kg. At liveweights arranged in logarithmic progression between birth and 249 kg, three calves of each treatment group were killed for analysis of body composition. Before and after weaning, the Friesians grew more rapidly than the Jerseys on the same treatment. They were also more efficient in terms of feed intake per liveweight gain. Similarly, calves of both breeds on the high plane of nutrition grew faster and more efficiently than the corresponding calves on the low plane. The growth of the Friesians was affected less by the feed restriction than was that of the Jerseys. After weaning, the feed conversion efficiency of the Friesians did not change significantly with increasing liveweight. Feed efficiency was reduced in the Jerseys as they grew larger. These results are compared with others from the literature and are discussed in relation to the difference in mature size between these breeds.