The present study was carried out to estimate (co)variance components and genetic parameters for some productivity traits of Kermani ewes using data collected during a 16-year period (1995-2011) at Breeding Station of Kermani sheep, located in Shahrebabak city, Kerman province, Iran. The traits studied were: conception rate (CR), litter size at birth per ewe exposed (LSB/EE), litter size at weaning per ewe exposed (LSW/EE), total litter weight at birth per ewe exposed (TLWB/EE) and total litter weight at weaning per ewe exposed (TLWW/EE). Genetic analysis of the studied traits was performed applying restricted maximum likelihood (REML) procedure under uni- and multivariate repeatability models. Ewe age at lambing and lambing year had significant effects on all the studied traits (P<0.01). Weaning age of lambs had significant effect on TLWW/EE as a linear covariate (P<0.01). Estimates of direct heritability for CR, LSB/EE, LSW/EE, TLWB/EE and TLWW/EE were 0.08, 0.06, 0.07, 0.11 and 0.15, respectively, while corresponding repeatability estimates were 0.25, 0.19, 0.18, 0.25 and 0.31, respectively. There were found no antagonist relationship among the studied traits in terms of phenotypic, genetic and environmental effects. Direct genetic correlation estimates among the studied traits varied from low estimate of 0.16 for CR-TLWB/EE to high estimate 0.95 for CR-LSB/EE. Low to medium phenotypic correlation estimates of 0.07 (LSB/EE-TLWW/EE) and 0.46 (TLWB/EE-TLWW/EE) were found. It seems that selection based on TLWW/EE, as an efficient selection criterion bring about genetic progress for ewe productivity traits in Kermani sheep.
