Effects of the Double-Ovsynch program on some reproductive parameters at different postpartum days in dairy cows [Postpartum farkli{dotless} günlerdeki i̇neklere UYGULANAN double-ovsynch programi{dotless}ni{dotless}n bazi{dotless} reprodüktif parametrelere etkileri]

The aim of this study was to evaluate the effect of double-ovsynch protocol on various fertility parameters at different postpartum days in dairy cows. fifty-one holstein cows were used and allocated into 4 groups. group 1,group 2 and group 3 each contained 12 cows on the 25th,32nd and 39th day of postpartum (as considered day 0),respectively. group 4 (n=15) served as control group that nothing was applied until 40th day of postpartum then artificial insemination was performed at observed estrus. cows in groups 1-3 were treated with gnrh on day 0,pgf2α on day 7,gnrh on day 10,gnrh on day 17 and pgf2α on day 24. the injection of gnrh was applied 56 h after the second pgf2α injection and then timed artificial insemination (tai) was performed at 16-20 h later (average 18th hour). the synchronisation rates changed between 66.67% and 91.67% in the study groups however a higher rate was observed in the groups 2 and 3. the lowest level of estrus symptoms at the tai was seen in the groups 1-3 (p<0.05). the highest pregnancy rate after the first tai (58.33%) was obtained in groups 2 and 3. the highest cumulative pregnancy rate (91.67%) were observed in groups 1 and 2. in conclusion,double-ovsynch protocol beginning at the different days of postpartum in dairy cow may provide a good reproductive performance without estrus detection.