Superovulation of nelore cows and heifers

Abstract

A study of the effects of breed and nutrition on the productive traits of Nelore, Guzerá, Charolais and Canchim cattle found in south-east Brazil was undertaken as part of an overall research programme to differentiate between carcase classes with a view to elaborating carcase classification proposals.The forty animals used in this study were divided into two treatment groups representing intensive and extensive feeding systems. Recovered data were analysed to determine the effects of breed, treatment and possible breed-treatment interaction on the proportions of internal and external offals and gross carcase composition.The results demonstrated that although some differences in carcase composition could be attributed to breed effect, most were caused by the varying nutrional status of the animals pre-slaughter. The Charolais—and, to a lesser extent, the Canchim animals—were seriously maladjusted to the harsh range conditions and showed lower daily liveweight gains and reduced liveweight at slaughter. The significantly lower special hindquarters and higher forequarter proportions in the Zebu animals were thought to be due to the cervical enlargement of the rhomboid muscle and earlier sexual maturity in the Bos indicus animals.