Yousef Naderi - Department of Animal Science, Astara Branch, Islamic Azad University, Astara, IRAN
Mohammad Mazarei - Department of Animal Science, Astara Branch, Islamic Azad University, Astara, IRAN

A number of 8733 body weight records of 1973 lambs from 110 sires and 550 dams, collected between 1990 to 2014 from the rearing and breeding station of Makouei sheep in Makoo of West Azerbaijan province. Contemporary groups (age of dam, sex of lamb, type of birth and year-season of birth) and fixed regression of body weight on age were considered as fixed parts of the models. Random regressions of direct additive genetic, maternal and direct permanent environmental were random parts of the models. Despite low, positive genetic trends were found for growth traits and genetic trend estimates for growth performance showed that selection decisions made during the breeding program effectively improved the body weight traits.

Makooei Sheep, Random Regression Model, Genetic Trend