Genetic and environmental parameters for reproduction traits in Holstein cows in East Azerbaijan province

Genetic and phenotypic parameters were estimated for calving interval (CI)، open days (OD)، conception rate (CR)، gestation length (GL)، number of service per conception (NSPC)، interval from calving to first service (CTFS)، age at first calving (AFC) and Interval from first service to conception (FSTC) in 6 large Holstein dairy herds in East Azerbaijan province. The reproductive traits used in this study were collected from 1997 to 2009 at the Livestock Service of the Ministry of Jihad Agriculture. Genetic and phenotypic parameters of the traits were estimated using restricted maximum likelihood (REML) procedure under univarite and multivariate animal models applying WOMBAT software. The estimated heritabilities for CI، OD، CR، GL، NSPC، CTFS، AFC and FSTC were 0. 047، 0. 041، 0. 073، 0. 060، 0. 071، 0. 21، 0. 12 and 0. 044، respectively. The estimated genetic correlations among the traits ranged from 0. 002 for OD–NSPC to 0. 97 for FSTC–NSPC. The estimated phenotypic correlations were generally lower than those of genetic correlations and ranged from 0. 001 to 0. 71.