Comparison of genetic gain for milk production in Holstein cows in Iran resulted from progeny test and genomic selection and effect of number of young bulls on it

In this study genetic gain from a progeny testing program corresponding to the characteristics of Holstein population in Iran and an equivalent genomic selection program in terms of number of needed male and female parents were compared and the effect of number young bull on the genetic gain in these two programs was evaluated. Selection objective included the milk production. Genetic gain for milk production from four path selection was estimated using gene flow method over a 150-year horizon. The results showed that the progeny testing and genomic selection differed, in addition to selection accuracy, by selection intensity and generation interval. The annual genetic gain from progeny testing was 114.7 and from genomic selection was 173.7kg. The results of the change the number of young bulls from 50 to 300 showed genetic gains varied between 106.11 to 117.53 kg by progeny testing and between 160.95 to 185.38 kg in genomic selection. In both programs the genetic gain was more sensitive to the change in the number of young bull when it was less than 100.In general this study showed that the genetic gain obtained from genomic selection could be higher than that of progeny testing by more than 50% because of shorter generation interval. But this superiority was affected by the number of young bull and would reach to minimum level at 75 young bulls.