Effect of Nutritional Level Imposed from Birth to Eight Months of Age on Subsequent Growth and Development Patterns of Full-Fed Beef Calves

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Abstract
Sixty Hereford steer calves from 5 groups of dams of similar genetic background were used in this study. From birth to 8 months of age, each of the 5 groups of calves were subjected to one of the following nutritional levels; very restricted, restricted, normal, high and very high. A random sample of calves from each of the 5 groups was slaughtered at 8 months. Remaining calves were then fed the same finishing ration until attaining a similar market weight of approximately 430g. There was an increase in live weight and in total gain, to 8 months, with an increase in nutritional level. Upon slaughter at 8 months, of age, significant differences, favoring the higher level calves were ob- tained in dressing percent, carcass grade and skeletal scale. As the level of nutrition decreased, significantly less lean, fat and bone were produced. The relative retardation of growth was greatest in fat tissue, followed by lean and bone respectively. In order to reach a constant market weight, more feedlot gain was required of the calves subjected to lower levels of nutrition from birth to 8 months of age. Average daily feedlot gains were not significantly different. Therefore, calves subjected to the lower planes of nutrition during early life required more days in the feedlot to attain the 430kg constant marked weight. No significant differences in carcass merit, skeletal scale and composition could be noted when animals were slaughtered following a feedlot period to a constant marked weight. Though statistically non-significant, carcasses from animals slaughtered at a constant weight tended to contain a greater percentage of lean and bone, with a lower percentage of fat, the level of nutrition increased during early life.