Estimates of Genetic and Phenotypic Parameters for Composite Reproductive Traits in Baluchi Ewes



Records of 2593 baluchi ewes, obtained from Baluchi Sheep Breeding Station in Abbas Abad, Mashhad, were used to estimate genetic parameters for total weight of lamb weaned per ewe joined (TWW/WJ) in different parities. Estimates of heritability for TWW1/EJ, TWW2/EJ, TWW3.EJ and TWW4/EJ were 0.112 ? 0.030, 0.028 ? 0.030, 0.075 ? 0.060 and 0.135 ? 0.120, respectively. Direct additive genetic correlations were positive and high, to medium ranging from 0.955 (between TWW1/EJ and TWW2/EJ) to 0.362 (between TWW2/EJ and TWW4/EJ). The corresponding estimates for phenotypic correlations were also positive, but lower than genetic correlations and varied from 0.147 (between TWW3/EJ and TWW4/EJ) to 0.204 (between TWW2/EJ and TWW4/EJ). The high genetic correlation between TWW1\EJ and other composite reproduction traits indicated that lifetime reproductive perfomance can be improved through selection for TWW1\EJ.