Aim OvSynch is a hormonal protocol for synchronization of estrus and use of artificial insemination (AI) at an optimal time without adverse effects on the ovaries or uterus. This study investigated the use of noninvasive color Doppler ultrasound to assess changes in uterine and vaginal blood flow during the Ovsynch program for synchronization of estrus and its relation to the pregnancy rates in Holstein cows. Materials and methods The experimental cows received an intramuscular dose of 10 μg of a GnRH analogue (G1), followed 7 days later with an intramuscular injection of synthetic prostaglandin F2α (P: PGF2α) analogue (500 μg cloprostenol sodium), and given a 10 μg, injection of the GnRH analogue (G2) i.m. 48 h after the PGF2α treatment, and the cows were bred 14-16 h after. Uterine and vaginal perfusion were investigated by performing transrectal Doppler ultrasonography of both the uterine and vaginal arteries in Holstein cows at different time points during the Ovsynch program to determine: peak systolic velocity (PSV), time-averaged maximum velocity (TAMV), the volume of blood flow (BFV), pulsatility index (PI), resistance index (RI), resistance impedance (S/D) and diameters of uterine (UA) and vaginal (VA) arteries. Steroid hormones were also assayed. Transrectal ultrasonography (TUS) was performed at 32 and 60 days to confirm the pregnancy per artificial insemination (P/AI). Results The uterine PSV, TAMV, and PV were greater at the time of the cloprostenol sodium and second GnRH injections ( p< 0.05) than at the time of the first GnRH injection. The vaginal PSV, PV were greater at the time of the cloprostenol sodium than at the time of the first and second GnRH injections ( p< 0.05). The receiver operating characteristic curve (ROC curve) indicated a high correlation between the uterine and vaginal blood flow and the rate of the pregnancy ( p< 0.05). The area under the ROC curve was 0.920 and 0.87 ( p< 0.05) for vaginal and uterine arteries respectively at time of G2. The serum levels of progesterone, estrogen and cortisol were correlated with the P/AI ( p< 0.05). The P/AI significantly decreased from 43.9 % at 32 d to 35.37 % at 60 d. Conclusion These results indicate that noninvasive Doppler ultrasonography is a valid method to evaluate changes in the characteristics of uterine and vaginal blood flow in cows during the Ovsynch protocol. Furthermore, vaginal and uterine blood flow are two determinant factors for the higher conception rates in Holstein dairy cows.

This review focused on the various methods for controlling estrous cycles in well-managed dairy cows. Because up to 70% of dairy cows may stay non-pregnant after an AI procedure, an effective approach for identifying and reinseminating open cows is essential for dairy herds to achieve optimal reproductive performance. Overall, well-managed dairy farms with effective estrus detection programs inseminate 50% or more of non-pregnant cows after behavioral estrus is detected. Cows not detected in estrus are admitted in a resynchronization of ovulation procedure to receive a timed AI (TAI) service to avoid a long interbreeding interval. In Egypt, a widely used program involves starting the Ovsynch protocol (GnRH-7 d-PGF2-56 h-GnRH-16 to 20 h-TAI) 32 days after an initial AI, regardless of pregnancy status. Previous studies have proven that there was no difference in pregnancy/artificial insemination (P/AI) between Ovsynch+P4 and Presynch-Ovsynch, both protocols were equally effective in improving the fertility of cows with a CL 15 mm. The review also addressed different methods for synchronization of ovulation and different factors affecting the selection of the management program.

The purpose of this study was to see how the Ovsynch, modified Ovsynch, presynch, and modified presynch protocols affected postpartum reproductive performance in dairy cows. Design: Randomized controlled experimental study Animals: The current research involved 412 dairy cows. Procedures: The cows were split into four groups: GnRH was given on day 0, PGF2∝ on day 7, and GnRH on day 9. Group 1: (Ovsynch protocol, n= 117) received GnRH on day 0 and PGF2∝ on day 7. Group 2 (modified Ovsynch, n=113): PMSG on day 0, PGF2 on day 7, and PMSG on day 9. Group 3 (presynch protocol, n=98) got two doses of PGF2 14 days apart, which allowed for a 12-day delay in the start of Ovsynch. Group 4 (modified presynch protocol, n=84) got two PGF2∝ doses 14 days apart, which was 12 days before the start of modified Ovsynch. All of the animals were artificially inseminated 16 hours following their last GnRH or PMSG dose. The ovarian rebound, number of services per conception, days open, and calving interval were the measures for determining reproductive performance for the dairy cows. Results:The main effect of the synchronisation program showed no significance for ovarian rebound (P >0.05). The S/C, days open and calving intervals were decreased significantly (P＜0.05) in the 3rd and 4th groups when compared with the cows that received either GPG or PMSG treatment only. All four groups had a conception rate of 35.04 (41/117), 40.7 (46/113), 44.8 (44/98), and 57.14 (48/84) %, respectively (P＜0.05). Conclusion and clinical relevance:It was investigated that giving two PGF2 injections before Ovsynch, either utilizing GnRH or PMSG methods, improved the reproductive performance of dairy cows. Furthermore, cows given PMSG had a greater conception rate than cows given GnRH.

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Aim OvSynch is a hormonal protocol for synchronization of estrus and use of artificial insemination (AI) at an optimal time without adverse effects on the ovaries or uterus. This study investigated the use of noninvasive color Doppler ultrasound to assess changes in uterine and vaginal blood flow during the Ovsynch program for synchronization of estrus and its relation to the pregnancy rates in Holstein cows. Materials and methods The experimental cows received an intramuscular dose of 10 µg of a GnRH analogue (G1), followed 7 days later with an intramuscular injection of synthetic prostaglandin F2α (P: PGF2α) analogue (500 µg cloprostenol sodium), and given a 10 µg, injection of the GnRH analogue (G2) i.m. (2.5ml/animal) 48 h after the PGF2a treatment, and the cows were bred 14–16 h after. Uterine and vaginal perfusion were investigated by performing transrectal Doppler ultrasonography of both the middle uterine and vaginal arteries in Holstein cows at different time points during the Ovsynch program to determine: peak systolic velocity (PSV), time-averaged maximum velocity (TAMV), the volume of blood flow (BFV), pulsatility index (PI), resistance index (RI), resistance impedance (S/D) and diameters of uterine (UA) and vaginal (VA) arteries. Steroid hormones were also considered. Transrectal ultrasonography (TUS) was performed at 32 and 60 days to confirm the pregnancy per artificial insemination (P/AI). Results The uterine PSV, TAMV, and PV were greater at the time of the cloprostenol sodium and second GnRH injections (p < 0.05) than at the time of the first GnRH injection. The vaginal PSV, PV were greater at the time of the cloprostenol sodium than at the time of the first and second GnRH injections (p < 0.05). The receiver operating characteristic curve (ROC curve) indicated a higher correlation between the uterine and vaginal blood flow and the rate of the pregnancy (p < 0.05). The ROC curve for the vaginal artery was 0.920 and that for uterine blood flow was 0.870 (p < 0.05) at the G2 (p < 0.05). The serum levels of progesterone, estrogen and cortisol were correlated with the P/AI (p < 0.05). The P/AI significantly decreased from 43.9% at 32 d to 35.37% at 60 d. Conclusion These results indicate that noninvasive Doppler ultrasonography is a valid method to evaluate changes in the characteristics of uterine and vaginal blood flow in cows during the Ovsynch protocol. Furthermore, vaginal and uterine blood flow are two determinant factors for the higher conception rates in Holstein dairy cows.