| Summary: | The influence of the nutritive plane on the early growth of the Holstein calf has been investigated. Particular attention has been given to near-maximal growth rates, and to the ability of calves to exhibit compensatory growth after nutrient restriction is removed.
A whole milk feeding standard, intended to allow maximum consumption, was established and used as the plane of nutrition for a group of high-plane calves. A second group of calves was fed milk at a lower plane for a period, before being realimentated to the same high plane that their contemporaries had received. Metabolic rate measurements were made on all calves at regular intervals. The animals of both groups were slaughtered at a body weight of 113 kgm (250 lb) and various measurements were taken from the dissected carcasses.
The high-plane feeding standard proved to be quite satisfactory and permitted weight gains from 1.09 to 1.34 kgm/ day for the calves reared continuously on this plane. Highly reproducible rates of gain were displayed by the low-plane calves, both during the periods of restriction and realimentation. The growth rates of the low-plane calves in the latter period exceeded those of the high-plane animals, being from 1.45 to 1.6l kgm/day. The possible reasons for this increased growth capability are discussed in relation to the studies of other workers on compensatory growth.
Nutrient restriction depressed the metabolic rates of low-plane calves below those exhibited by their high-plane partners of equal weight. Upon realimentation, the metabolic rates of the previously-restricted calves rose quite rapidly to levels commensurate with the heat losses of the high-plane animals.
The carcass dissection studies did not reveal extensive modifications in body composition that could be attributed to the treatments. The growth of certain visceral organs was retarded or accelerated by the nutritive planes imposed, but the musculature and skeleton were apparently unaffected by the pattern of growth.
The yield of edible meat was essentially the same for both groups of animals, despite a lower consumption of milk by the calves whose growth had been interrupted. A model, for comparison of the relative efficiencies of restricted and unrestricted meat-producing animals, is suggested. === Land and Food Systems, Faculty of === Graduate
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