Estimation of (Co)variance components for economical traits in Moghani sheep 2 Mehdi Bayeriyar 1 1 , A Asghar Aslaminejad , Hadi Farajiarogh 1 , Fatemeh Bahri Beinabaj 2 Ferdowsi University of Mashhad, Mashhad, Islamic Republic of Iran, 1 , M Danesh Mesgaran 1 University of Tabriz, East Azerbijan, Islamic Republic of Iran Email: hadifaraji.um@gmail.com Introduction Lamb weight is an important component of marketing in lamb production. Growth, carcass and some other traits are not only influenced by the direct genetic composition of the individual and the environment under which the animal is raised, but also were affected by the maternal genetic composition and maternal environment. When maternal genetic effects are important, but not accounted for in the evaluation, heritability estimates are biased upwards and realised selection-efficiency would reduce. Development of effective genetic evaluation and improvement programmes requires knowledge of the genetic parameters for these economically important production traits. The aim of this study was estimation of (co)variance components for some growth traits in Moghani sheep. Material and methods Pedigree of 4876 Moghani lambs from 242 sires and 1394 dams were used in this study. Data were collected from year 2000 to 2010 at Jafar Abad sheep breeding station in Ardebil province of Iran. Five traits were considered in the analyses, i.e. Birth weight (BW); Weaning weight (WW); 6-month weight (W6); 9-month weight (W9) and Yearling weight (YW). The data analysed by REML, and Animal model was used in eight models of DFREML for the estimations. The best model was chosen based on the Log Likelihood ratio test. The following model (Maria et al., 1993) was fitted to the data: Y = Xb + Za + Zm + Zpe + e Where Y is vector of observation for traits; b, vector of fixed effects; a, vector of direct random effects; m, vector of maternal random effects; pe, vector of permanent environmental effects; e, vector of random residual effects; X, Z m p , Z and Z p a m are incidence matrices for fixed, direct, maternal and permanent environmental effects, respectively.

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