Effect of estrus resynchronization on the reproductive efficiency of zebu cows.

The aim of this study was to develop a resynchronization strategy before the return of estrus in cows diagnosed as not pregnant after fixed-time artificial insemination (TAI). A total of 839 cows, approximately 45 days postpartum, were synchronized using TAI. On day 0, intravaginal progesterone-releasing devices were inserted and 2 mg of estradiol benzoate was administered. Eight days later (D8), the progesterone-releasing devices were removed and estradiol cypionate (0.5 mg, eCG (300 IU)) and prostaglandin (7.5 mg) were administered. All cows were inseminated between 48 and 56 hours after device removal (D10). Thirty days after TAI, cows that were not diagnosed as pregnant by ultrasound were immediately resynchronized and again inseminated at a fixed time. The hormonal protocol used in the first and second rounds of TAI was the same. The pregnancy rate after the first TAI was 52% and after the second TAI it was 49%. The increase in the total pregnancy rate (synchronization + second estrus synchronization) compared to a single synchronization was 23.5%.". In conclusion, resynchronization of estrus and ovulation in zebu cows that had previously undergone TAI protocols is effective in increasing the reproductive efficiency. This article is protected by copyright. All rights reserved.