Role of imprinting effects on estimation of variance due to parent of origin effects for growth traits in Zandi sheep

In this study parent of origin effects for growth traits in Zandi sheep was estimated using gametic relationship matrix. Data was collected from the Khojir Breeding Station of Zandi sheep, using 9562 sheep between 1991 and 2011. The traits such as birth, weaning, 6-month, 9-month and yearling weights were studied. (Co) variance components were estimated by WOMBAT software through Average Information REML algorithm (AI-REML). To estimate imprinting variances, a two steps method was used. In the first step, the best model was selected according to the lowest AIC, then in the second step paternal and/or maternal imprinting effects were added to the selected models. In all traits, adding imprinting effects in the models had beneficial effects on our estimates. Paternal imprinting effects ranged from 6-8 presents for weaning and 9-month weights, respectively of total phenotypic variance. Maternal imprinting effects ranged from 7-15 presents for yearling and birth weights, respectively. Adding imprinting effects in models reduced the heritability and maternal genetic. Adding parent of origin (imprinting) effect in models could have beneficial effects for analyses of body weight traits in sheep.