Influence of preweaning nutrition on growth of Angus calves provided a postweaning nutritional system resulting in discontinuous growth.

Postweaning growth patterns and preweaning milk and forage intake were observed over a 4-yr period for 137 Angus calves allowed either fescue-legume or fescue pastures preweaning. After weaning, calves grazed fescue pasture until spring for a slow growth phase and then fescue, orchard grass, bluegrass and ladino clover pastures for 4 mo. Following this period, the calves were confined and fed shelled corn and a 36% crude protein supplement until they reached 12 mm of fat over the 12th rib. The spring growing period and the finishing period were classified as a rapid growth phase. Calves that were fatter at weaning lost more fat, but gained more in wither height during the slow growth phase, than those that were thinner at weaning. Apparently, fatter calves were more capable of continuous skeletal growth on a low plane of nutrition because they could retrieve fat energy for this growth. In spring, calves that had been relatively fat at weaning held no advantage in fatness, but had larger frames. Therefore, during the rapid growth phase, they were able to fatten more rapidly than those that were thinner at weaning. Also, calves that were more efficient in preweaning growth had more capacity for rapid postweaning growth when restricted to relatively low quality pasture. Preweaning pasture type influenced pattern of postweaning growth. Part of this influence was associated with differences detected at weaning. An additional part was associated with efficiency of forage and milk utilization during the preweaning phase.