Estimates of Genetic Correlations between Carcass and Growth Traits and Scrotal Circumference in Nelore Cattle

INTRODUCTION The demand for high quality meat and the competition with other protein sources imposes the introduction of new technologies in the Brazilian beef cattle system of production. Most of breeding evaluation programs in Brazil, have given emphasis to records of weights and scrotal circumference (SC) at different ages, ignoring carcass traits (CT) and other growth traits. Carcass traits can be quickly determined by real-time ultrasound, without the need to slaughter the animals and without assigning visual scores, being therefore, an objective process, enabling estimates of genetic values in young animals before the first mating. Herring et al. (1998) pointed out that this technique is an objective and accurate tool in the selection for muscling, subcutaneous fat, marbling and retail beef yield. Considering the possibility of reaching new markets and the increasing demand for better meat quality, CT and hip height (i.e., frame score) certainly should be included in the Brazilian breeding programs. In this way, the objective of the present work was to study how these traits respond to selection and their possible genetic correlations with weight and SC at different ages.