Genetic Study of Birth Weight and Weaning Weight in Najdi Calves

In this study data on birth weight and weaning weight of Najdi calves, collected from 1989-2004 by Najdi cattle Research Station, located in Khuzestan province were analyzed. Mean and standard deviation of birth weight and weaning weight were 18.08 +/- 3.17 and 49.56 +/- 13.10, respectively. Based on appropriate model, direct and maternal heritability for birth weight and weaning weight were estimated 0.37, 0.08, 0.11 and 0.09, respectively. Correlation between direct and maternal effect were 0.56 and -0.16 for birth weight and weaning weight. Genetic, phenotypic and environmental correlations between two traits were estimated as 0.50, 0.64 and 0.44. Mean inbreeding coefficient was 0.78% with maximum level of 25%. The regression coefficients of birth weight and weaning weight on inbreeding coefficient were -0.182 and -0.0627 kg, respectively. The results of this study showed that the mean inbreeding level of population was low and the effect of inbreeding coefficient on these traits was not significant.