Improvement of Reproductive and Growth Traits by Selecting Ewes Based on Reproductive Composite Traits in Baluchi Sheep

In this study, 1973-2003 data of 12,328 animals from Abbasabad Baluchi Sheep Breeding Station, Iran, were used to estimate genetic and phenotypic correlations between Total Weight of lambs Weaned per Ewe Joined in the first, 2nd, 3rd and 4th lambing (TWW1/EJ, TWW2/EJ, TWW3/EJ, and TWW4/EJ, respectively), and TWW of the total four lambing (TWWt/EJ). Also, the study aimed to estimate correlations of TWW1/EJ...TWW4/EJ and Birth Weight (BW) as well as Weaning Weight (WW). The (co)variance components and genetic correlations were estimated by DFREML procedures. Genetic correlation between TWW1/EJ and TWWt/EJ was high and positive (0.76). Genetic correlations of TWW/EJ in different lambing with BW and WW ranged from 0.16 to 0.32 and 0.95 to 0.97, respectively. Repeatability of TWW/EJ for lambing 1-4 was 0.15. Results suggested that selection for increased lifetime reproductive performance could be based on TWW1/EJ in the first lambing. Overall, results indicate that TWW/EJ, as an important but sex-limited trait, may be used in selection criterion to indirectly improve the related traits.

Improvement of Reproductive and Growth Traits by Selecting Ewes Based on Reproductive Composite Traits in Baluchi Sheep Keywords:

Birth weight , Composite traits , Heritability , Weaning weight.