Growth of Mashona cattle on range in Zimbabwe. I. Environmental influences on liveweight and weight gain.

Data from 1,456 purebred Mashona calves were analysed to determine environmental influences on growth rate and liveweight at birth, weaning (205 days) and 18 months of age. Calves were born between mid-September and mid-December each year. Year of birth was highly significant for all traits (P less than 0.001). Pre-weaning liveweight and weight gain increased as age of dam increased to seven years after which growth tended to decline. Post-weaning compensatory growth was apparent in calves of young dams. Male calves grew faster and were heavier at all stages than female calves (P less than 0.001). Calves from previously non-lactating cows grew more rapidly and were heavier at all ages than those from previously lactating cows. Birth weight increased as calving season advanced and calves born late maintained their growth advantage until 18 months of age. The results indicate that environmental influences experienced in early life persist long after weaning.