The effect of modified G6G and Double Ovsynch Synchronization protocols on fertility at first insemination in dairy cows

This study was carried out to compare the effciency of different synchronization methods on fertility by performing fixed-time insemination, such as Double Ovsynch (DO) and Modified G6G (MG6GP) in the postpartum first insemination of dairy cows. The study was designed as group;1st group DO-primiparous (first lactation cows) (n:106), 2nd group MG6GP-primiparous (n:105), 3rd group DO-multiparous (2 or more lactations cows) (n:392) and 4; MG6GP- multiparous (n:385). Double Ovsynch (DO) synchronization protocol (GnRH-7day-PGF2α-3day-GnRH-7day-GnRH-7day-PGF2α-1day-PGF2α-36hr-GnRH-16-18hr fixed-time artificial insemination) was initiated on postpartum 51±3 days, Modified G6G (MG6GP) synchronization protocol (PGF2α-3day-GnRH-7day-GnRH-7day-PGF2α-1day-PGF2α-36hr-GnRH-16-18hr fixed time artificial insemination) was initiated postpartum 58±3 days and fixed time artificial insemination of all groups was performed at 78±3 days in milk (DIM). Pregnancy examination were performed two times at days 34±3 and 63±3 following artificial insemination with ultrasonographic imaging method (USG). Synchronization start in study groups with multiparous cows, at the beginning of breeding ovsynch and at the time of artificial insemination, ovaries and uterus were examined by ultrasonographic imaging. As a result of this study, primiparous cows a pregnancy rate of 40.56% (43/106) was achieved in those synchronized with DO and 43.80% (46/105) in cows synchronized with MG6GP. In multiparous cows; a pregnancy rate of 39.79% (156/392) was achieved in cows synchronized with DO, and 46.23% (178/385) in cows synchronized with MG6GP. As a result, a higher pregnancy rate was obtained in primiparous and multiparous cows that were the MG6GP synchronization protocol at the postpartum first insemination, compared to those that were synchronized and inseminated with DO. However, this difference was not statistically significant (p˃0.05). Keywords: Dairy cows, Double Ovsynch, G6G, MG6GP, Synchronization.