Abstract

    Pedigree and performance records of 296 Bhagnari and Droughtmaster x Bhagnari crossbred cows maintained at the Beef Production Research Centre, Sibi (Baluchistan) accumulated, over a period of 30 years from 1969 to 1999, were utilized for the present study. The least squares means for birth weight, weaning weight and pre-weaning average daily gain were 23.49 ± 3.76, 107.46 ± 19.00 and 390.00 ± 97g having coefficients of variation of 12.89, 13.75 and 13.75%, respectively. Year of birth significantly influenced birth weight, weaning weight and pre-weaning average daily gain, while season of birth appeared to be a non-significant source of variation for all of the performance traits studied. Genetic group of the cows had a significant effect on birth weight, while other traits including weaning weight and pre- weaning average daily gain, were non-significantly affected by the genetic group of the cow. Genetic group of the dam had a non-significant influence on body weights at birth and weaning (P>0.05). The heritability estimates of birth weight, weaning weight and pre-weaning average daily gain were found to be 0.09 ±  0.02, 0.09 ± 0.01, and 0.01 ± 0.01, respectively. The estimates of phenotypic and genetic correlation between birth weight and weaning weight were -0.23 and -0.74, respectively. The estimated breeding values ranged from -171.44 to 242.48 kg for birth weight and from -171.44 to 22.48 kg for weaning weight. Estimated breeding values obtained were used to compute the genetic trends for various performance traits. The genetic trends for birth weight was negative and for weaning weight it was slightly positive. All phenotypic trends were negative with the exception of the one for weaning weight, which was slightly positive.