estimation of genetic parameters for growth and reproduction traits and genetic trends of growth traits in zel sheep breed under rural production system

in this study records of 15723, 12108 and 5236 zel sheep for birth weight (bw), weaning weight (ww) and 6-month weight (6mw) traits were used. data has been collected by the jahad-e-keshavarzi organization of province of mazandaran during 1994-2009. the heritability of direct and maternal of growth traits was estimated using the univariate analysis with restricted maximum likelihood (reml). in order to fit an appropriate model, six models via adding and elimination of maternal genetic effects and maternal permanent environmental was applied. the likelihood ratio test showed that the model with direct genetic effects and maternal additive genetic, regardless covariance between them, were appropriate for birth and weaning weight and the model with direct genetic effects and permanent environmental for 6-month weight were appropriate. heritability of reproduction traits using multiple trait analysis were estimated as 0.05 for number of lambs born per ewe and 0.14 for total litter weight at birth per ewe. direct genetic trend of birth weight, weaning weight and 6-month weight through univariate and multivariate analysis were estimated 1.91±0.07 and 2.53±1.10, 98.50±10.40 and 105.38±25.20, 73.23±21.20 and 78.46±33.40 gr per year, respectively. maternal genetic trend of birth weight through univariate and multivariate analysis were estimated 2.94±1.21 and 3.07±2.49 gr per year, respectively.