MGENETIC EVALUATION OF COMPOSITE REPRODUCTIVE TRAITS IN GHEZEL SHEEP H. Baneh1,* and J. Ahmadpanah2 - H. Baneh; J. Ahmadpanah (Journal of Animal and Plant Sciences, 2020)
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<0.01) for LSB, TLWB, LMWLB, TLWW and LMWLW traits; proportions of phenotypic variance explained by the service sire effect were 0.03, 0.14, 0.21, 0.25 and 0.33, respectively. A significant genetic trend was found only for LMWLB (P<0.05).These results suggested that inclusion of permanent environmental and service sire effects in the model for ewe productivity traits may improve the accuracy of genetic evaluation. Also, improvement of reproductive traits in this breed may be achieved by selecting the elite rams.
Keywords: journal article; Ghezel sheep; genetic evaluation; reproductive performance; service sire effect; REML