Estimation of Genetic Parameters of Body Weight Traits in Ghezel Sheep (Report‪)‬

INTRODUCTION Ghezel sheep numbering about 2 million are raised in North Western of Iran. This breed is native, fat-tailed and large-sized (38.2 to 41.7 kg at yearling in female and male respectively). They are well adapted to mountainous and cold conditions (-22.8 to 38.3[degrees]C). They are raised primarily for meat, with milk and wool being of secondary importance (Baneh, 2009). Ways to increase meat production in sheep, in any system, are likely to be by producing more lambs per ewe and increasing growth performance of the lambs. The first objective can be achieved by increasing ewe productivity, including lambing rate and frequency, whereas the second objective requires enhancement of the growth potential and survival of lambs (Miraei-Ashtiani et al., 2007). Knowledge on genetic parameters and heritability are crucial for the genetic evaluation and for choosing the best selection schemes (Maxa et al., 2007). A number of studies have demonstrated that the inclusion of maternal effects in animal models has an important effect on the estimates of direct heritability (Nasholm and Danell, 1996; Maniatis and Pollott, 2002; Simm et al., 2002; Nasholm, 2004). There is no published data on the estimation of genetic parameters for body weight traits in this breed. Therefore, the objective of the present investigation was to obtain estimates of the genetic parameters for direct and maternal effects on body weight traits of Ghezel sheep by fitting three animal models, attempting to separate direct genetic, maternal genetic and maternal permanent environmental effects.