The present study aimed to evaluate the efficacy of different hormonal interventions in the treatment of cystic ovarian follicles (COF) based on different scenarios, including the size of the cyst and the presence of other follicles on the ovaries of dairy cows. A total of 199 Holstein cows with COF in the first 100 days postpartum were enrolled in the study. These cows were randomly assigned to the four following groups: 1) GnRH (G) group: intramuscular (IM) injections of 100 μg gonadorelin acetate on day 0 and 150 μg d-cloprostenol 7-12 days later, 2) double GnRH (DG) group: two IM injections of 100 μg gonadorelin acetate at 6 h intervals on day 0 and d-cloprostenol 7-12 days later, 3) intravaginal progesterone device (IPD) group: insertion of PRID Delta for 7-12 days and injection of d-cloprostenol on the withdrawal of PRID Delta, and 4) control group: IM injection of 2 mL sterile saline on day 0 and 7-12 days later. The cure rate of COF significantly improved in the G and DG groups, in comparison with the IPD and control groups. There was no significant difference between the cows in the G and DG groups. In the control group, animals with ovarian cysts smaller than 2.5 cm had a significantly greater self-cure rate, compared to the other cows. In conclusion, this field study demonstrated a good clinical cure in the groups of cows treated by GnRH. However, no improvement was observed in the reproductive performance of these animals.

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