Consequences of nutrition and growth retardation early in life for growth and composition of cattle and eating quality of beef

Severe growth retardation of cattle early in life is associated with reduced growth potential, resulting in smaller animals at any given age. Growth potential diminishes as age of onset of nutritional restriction declines, and severe, prolonged intra–uterine growth retardation may result in slower growth of cattle throughout life. Severe weight loss during the months immediately after weaning or slow growth after early– weaning also limits compensatory growth. Carcass composition of small and large newborns is similar at heavier market weights. At equivalent weights, calves grown slowly to weaning subsequently have carcasses of similar or leaner composition than those grown rapidly, unless high energy concentrate feed is provided post–weaning, causing increased fatness. Adverse effects of early–life growth on eating quality at market weights are not evident. When differences occur, they suggest that cattle restricted early in life may have slightly more tender meat. We propose that within pasture–based systems, plasticity of carcass tissues, particularly muscle which maintains a stem cell population, allows cattle growth–retarded early in life to attain normal composition at equivalent weights in the long–term, albeit at older ages. However, nutrition during recovery or following early–weaning is important in determining the subsequent composition of young, light–weight cattle relative to heavier counterparts.