اثر اسپرم تعيين جنسيت شده بر پيشرفت ژنتيكي گاوهاي شيري هلشتيان در يك برنامه آزمون نتاج

The effect of using sexed semen on genetic improvement of Holstein dairy cows in progeny test program

This study was designed to investigate the genetic effects of using sexed semen in a dairy cattle population. Amount of progress was evaluated in elite and commercial animals over 25 years of selection. Stochastic simulation was used for studying the genetic impacts of using sexed semen. Three strategies were compared: using sexed semen in cows and heifers (SSCH), using sexed semen in heifers and unsexed semen in cows (SSH), using unsexed semen in cows and heifers (WSS). The effect of using sexed semen was investigated on the genetic superiority. Moreover the effect was studied in four distinct paths of selection: active sires, young bulls, bull dams and milking cows. Average genetic superiority was obtained 0.1 and 0.03% for active sires, 1 and 0.6% for young bulls, 1.8 and 1.4% for bull dams and 12 and 9.5% for milking cows over 25 years of selection in SSCH and SSH strategies relative to WSS respectively. The result showed the effect of sexed semen on genetic superiority was significant in all groups except active sires. In the strategies that sexed semen was used, a large genetic advantage was observed in milking cows due to increasing selection intensity in this path.