Authors : M. Lotfi Farokhad, M. T. Beigi Nassiri, H. Roshanfekr, J. Fayazi and M. Mamouei
Abstract: Data and pedigree information of Arman lambs breed were collected in Abbas-Abad sheep breeding station, Mashhad, Iran by separating direct genetic, maternal genetic and maternal permanent environmental effects during 1997-2008. Genetic parameters of Birth Weight (BW), Weaning Weight (WW) and 6 Months Weight (6 MW) were estimated using mixed animal models of DFREML computer software. For all traits, the fix effects were lamb’s sex, birth type, age of dam and birth year and the random effects were direct additive genetic, maternal additive genetic, maternal permanent environment and maternal common environment. Six different models of analysis were fitted into each trait by ignoring or including maternal genetic effects or common environmental effects. Most appropriate model for each trait was determined by likelihood ratio test. The test indicate that models including direct and maternal genetic effect, without covariance between them was the most appropriate model for BW and WW and the model including effects common environmental due to dam was the most appropriate model for 6 MW. Direct heritability values of 0.094, 0.101 and 0.145 were estimates for BW, WW and 6 MW, respectively. Maternal heritability for birth and weaning weights 0.173 and 0.112 was estimated, respectively. The effect of permanent environmental due to dam for 6 months weight was estimated 0.089. The results generally show that considering effect of maternal in animal models are necessary for correct estimating direct heritability of growth trait of lambs.
M. Lotfi Farokhad, M. T. Beigi Nassiri, H. Roshanfekr, J. Fayazi and M. Mamouei, 2010. Genetic Parameters for Direct and Maternal Effects on Growth Traits of Arman Lambs. Research Journal of Biological Sciences, 5: 71-74.