Deslorelin as inductor of ovulation in bos taurus x bos indicus after previous exposure to intravaginal progesterone

This study aimed to assess the efficiency of deslorelin at inducing ovulation in crossbred cows previously exposed to intravaginal progesterone (P4). A total of 43 cows (Bos taurus × Bos indicus) were randomly divided into two groups, G1 (treated, n = 25) and G2 (control, n = 18). Both groups received an identical hormone protocol from day (D) 0 to D8: D0 = intravaginal P4 + estradiol benzoate (2 mg) and D8 = P4 removal + cloprostenol (500 μg) + 400 IU of equine chorionic gonadotropin (eCG) + ovarian ultrasonography. The ovaries were scanned on D9. On D10, G1 received deslorelin [150 mg, intramuscularly (IM)] and G2 no treatment. The ovaries were examined ultrasonographically at 6-h intervals until ovulation on D15. The ovulation rates in G1 and G2 were 100.0 and 73.3% (p < 0.05) and the intervals between deslorelin application and ovulation was 22.3 ± 7.6 and 33.3 ± 5.3 h (p < 0.05), respectively. In conclusion, intramuscular administration of deslorelin effectively induced ovulation in cows previously treated with progesterone; deslorelin promoted ovulation within 22.3 h of its administration.