GENETIC EVALUATION OF COMPOSITE REPRODUCTIVE TRAITS IN GHEZEL SHEEP

This study was carried out to estimate genetic parameters and trends for reproductive performances of Ghezel sheep. The traits included in the analyses were litter size at birth (LSB) and weaning (LSW), and litter mean weight per lamb born (LMWLB) and weaned (LMWLW) as basic traits, and total litter weight at birth (TLWB) and weaning (TLWW) as composite traits. Direct genetic trends were obtained by regressing means of predicted breeding values from the best model on birth year. Direct heritability estimates for LSB, TLWB, LMWLB, LSW, TLWW and LMWLW were 0.06, 0.04, 0.06, 0.01, 0.06 and 0.06, respectively. The permanent environmental effect was significant for LSW (0.09) and TLWB (0.04) and the service sire effect (0.14) influenced TLWB. Effects of service sire were highly significant (P