Effect of PGF2? and GnRH injections applied before ovsynch on pregnancy rates in cows and heifers

It is aimed to investigate the effect of PGF2? and GnRH injections (G6G/Ovsynch) applied before ovsynch protocol on pregnancy rates in cows and heifers. Holstein cows (n:196) without any clinically genital disorder in postpartum 50-100 days, weighing between 400 and 500 kg and Holstein heifers (n:169), 15-20 months old, weighing between 300-350 kg were used in three groups as materials.Animals in first group (Control: 40 cows, 40 heifers,) were inseminated artificially in their standing heat without using any hormonal treatment. In second group (Ovsynch: 37 cows, 80 heifers) ovysynch protocol (day 0, 10 µg IM GnRH, day 7, 500 µg IM PGF2?, day 9, 10 µg IM GnRH, artificial insemination 16 hours later after last injection) was performed. In third group (G6G/Ovsynch: 119 cows, 49 heifers) 500 µg PGF2? on day 0 and 10 µg GnRH on day 2 were injected and 6 days later after last injection ovysynch protocol was performed.In cows it was seen difference between control and others groups statistically in postpartum period days (p<0.05), whether there was no significant difference in groups according to weight, age and delivery number. In heifers, there was no difference in groups according to age and weight. Pregnancy rates in cows and heifers were detected 57,50-60,00%; 37,83-32,50% and 53,78-59,18 % according to the groups 1st, 2nd and 3rd, respectively.In pregnancy rates no differences were found in cows in groups statistically, however, it was seen that pregnancy rates were higher in group 1st and 3rd, than group 2nd. In heifers there was no significant difference between groups 1st and 3rd, but statistically the results in groups 1st and 3rd were higher and different from group 2nd (p<0.05).In conclusion, it was determined that the synchronization rates were higher in G6G/Ovsynch group than ovysnch group especially in heifers. Therefore, it is suggested that G6G/Ovsynch protocol is more useful for reproductive control protocol at heifers and cows in dairy farms due to low pregnancy rates of ovysynch protocol.