Phenotypic Changes of Maximum Daily Growth Trait in Baluchi Lambs

A total number of 116،984 weight records belonging to 12،397 Baluchi lambs reared in Abbas Abad breeding station during years 1978-2008 were used for phenotypic evaluation of maximum daily growth (MDG) and analysis of environmental factors affecting this trait. The initial data were performed by FOXPRO program and then Gompertz non-linear model was fitted on the weight records of individual lambs using non-linear procedure of SAS software. MDG was estimated for each lamb. The analysis of environmental factors on the trait was carried out by a linear mixed model consisting of effects of year and month of birth، lamb sex، birth type، covariates of dam age and birth weight، interaction between year and sex، year-birth type، birth type-sex، and random effect of lamb’s sire. All factors had significant effect on MDG. A non significant phenotypic trend (0. 092±0. 043 g/y) was revealed for MDG.