author(s)
Al-Waith KH, AL-Anbari NN and Mohamed TR

abstract
The present study was conducted in Al-Salam station for Dairy cattle / private sector, for the period from 1-11-2016 to 1-11-2017, to determine the relationship between genotype for the DRB3 and productive performance traits in Holstein cows. Results showed that total milk production in Holstein cows was highly significant (P<0.01) affected by genotypes of gene DRB3 and for cows with B (1628.36 ± 60.05 kg) and A genotype (1601.83 ± 60.25 Kg) compared with those which had C genotype (1510.77 ± 81.89 Kg), while the lactation period was not affected with different genotypes of DRB3 gene. There was no significant different in period from birth to the peak of lactation, while the length of peak production was significantly affected (P<0.05) with different genotypes of DRB3 gene and the highest average for B & A genotype 50.27 ± 1.73, 49.91± 1.74 day respectively, the fat percentage was significantly affected (P<0.05) by different genotypes of the DRB3 gene, the highest percentage reached in the cow’s milk which had genotype C 3.97 ± 0.22%, lactose, protein, non-fat solids and milk density were not significantly affected with the different of DRB3 gene genotypes.