Author(s): Akoz M, Aydin I, Ali Dinc D
Keywords:cow, presynch-ovsynch, reproductive parameters
In this study, the aim was to evaluate the presynch-ovsynch protocol on the intervals from calving to first insemination, calving to pregnancy, calving to calving in postpartum lactating cows. Lactating Holstein cows (n=104, 3-5 years old, 450-500 kg BW, 27±3 kg/day average milk yield) were enrolled in the study 26-41 days postpartum. Fifty of them were taken as the control group and 54 of them were the treated experimental group. The control group was not treated and the cows in estrus were inseminated. In the treated group the cows were injected with two PGF2 for presynchronization twice at every 14 days. Fourteen days after the second PGF2, ovsynch protocol was initiated (GnRH, day 0; PGF2, day 7; GnRH, day 9) and cows were inseminated 12-16 hours after second GnRH injection. Following AI, cows returning to estrus were inseminated at detected heat. Pregnancy diagnosis was performed by ultrasonography at 33-38 days after AI. Calving to first AI (days), calving to pregnancy (day), the number of AI per pregnancy, calving interval (days) for control cows were 96.08±8.20, 147.58±9.95, 2.19±0.20 and 430.50±10.90 and for the treated group 70.13±1.13, 101.76±5.70, 1.85±0.12 and 386.80±5.70, respectively. Compared to the control group, calving to first AI interval was shorter by 26 days, calving to pregnancy interval by 46 days and the calving interval by 44 days (p<0.001). Number of AI per pregnancy decreased numerically from 2.19 to 1.85. Pregnancy rates for the first AI was 47% for the control and 43% for the treated cows (p>0.05). As a result, by using the presynch-ovsynch protocol, the need for estrus detection was eliminated and inseminations were performed at a fixed time. Therefore, calving to first AI, calving to pregnancy, calving intervals and the number of AI per pregnancy were improved to the benefit of the farm.
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