مقایسه کارایی سه روش هم‌زمان‌سازی فحلی و تأثیر آنها بر برخی فراسنجه‌های تولیدمثلی در گاوهای شیری دارای مشکلات باروری

The decline in fertility among cows and heifers significantly impacts lactation performance. Estrus synchronization serves as an effective strategy in dairy herds to enhance fertility, resulting in a higher proportion of animals exhibiting estrus within a specified timeframe and subsequently undergoing artificial insemination. This study aimed to evaluate three estrus synchronization techniques, Heatsynch, Ovsynch, and Cosynch, concerning various reproductive parameters in dairy cows experiencing fertility problems and irregular estrus cycles. Four distinct experimental groups were established for this study. Thirty dairy cows with prior fertility issues, including endometritis, and a positive treatment response, were divided into three groups for different estrus synchronization methods. The fourth group included ten repeat breeder cows that did not undergo any synchronization process. In the Heatsynch method, an injection of 25 μg of gonadotropin was administered intramuscularly on day 0, followed by 1 mg of cloprostenol seven days later, and 2 mg of estradiol benzoate on day 8, with artificial insemination occurring 16 hours after. The Ovsynch method involved the initial injection of 25 μg of gonadotropin on day 0, followed by 1 mg of cloprostenol a week later, and an additional 25 μg of gonadotropin on day 9, with insemination occurring 16 hours later. The Cosynch approach mirrored the Ovsynch procedure but required that artificial insemination be conducted immediately after the final injection. Findings indicated that the Heatsynch synchronization method significantly enhanced the estrus and pregnancy rates (P<0.05). Hence, implementing estrus synchronization can effectively boost pregnancy rates in dairy cows encountering fertility challenges.