Growth and lipid metabolism in genetically different types of calves in a tropical environment

Growth rates were compared in suckling Britves of cows grazing in a tropical environment. The plasma lipid composition of calves and their dams was examined at intervals from 14 weeks post-partum to 3 weeks post-weaning. Growth rates from birth to weaning were significantly higher (P less than 0.01) in zubru than in British calves. Plasma concentrations of cholesterol and phospholipid were always higher in zebu than in British calves and in Brahman cross calves increased from 14 to 19 weeks of age followed by a decline prior to weaning at 30 weeks old. There were only small changes in the concentrations of these constituents in Africander cross and British calves during this period. At 3 weeks post-weaning the plasma concentrations of cholesterol were lower (P less than 0.01) than the pre-weaning levels in all calves. The concentrations of cholesterol, phospholipid and total ketones were higher (P less than 0.01) in zebu than in British cows. There weer significant relationships between plasma concentrations of cholesterol and growth rates in zebu calves and between growth rates of calves and the plasma cholesterol concentration of their dams in all breeds. The results suggest the possibility of using plasma cholesterol concentrations as indices of lactational status and growth rates of calves.