Genetic parameter estimates for body measurements and growth traits in South African Bonsmara cattle

Data of 7266 records of Bonsmara bull calves participating in on-farm growth tests were used to estimate genetic parameters fitting both univariate and multivariate models. Linear body measurements analyzed were shoulder height (SH), body length (BL) and scrotal circumference (SC). Growth traits included birth weight (BW), weaning weight (WW), final weight (FW) measured at the end of test, and average daily gain (ADG) from the beginning to the end of test period. A complete covariance structure was estimated amongst all the traits fitted. Heritability estimates for body measurements from univariate and multivariate analyses showed a general agreement though there was a tendency for an increase in estimates when multivariate models were fitted. Heritability estimates found in this study indicate that improvement through selection is possible for all the traits considered. Genetic correlations were favourably positive for body measurements and growth traits. The high genetic correlation (0.76 +/- 0.06) between shoulder height and body length suggests that selection for shoulder height may lead to rapid progress in body length since direct selection for this trait may be hampered by its low heritability. (C) 2002 Elsevier Science B.V. All rights reserved.