Ovulation induction in cows with Kisspeptin-10 in an estrus synchronization protocol

Introduction. In prepubertal heifers, Kisspeptin-10 has stimulated the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and in postpartum lactating cows, it has stimulated LH secretion without evidence of inducing ovulation. Objective. To induce ovulation using Kisspeptin-10 or gonadotropin-releasing hormone (GnRH) in beef-producing cows under subtropical conditions in Mexico. Materials and methods. The study was conducted in the northeastern region of the state of Puebla uring the years 2020 to 2021, with 252 Bos taurus x Bos indicus cows. The estrous synchronization protocol involved the insertion of an intravaginal device impregnated with progesterone (1.9 g) and intramuscular injection of 2 mg of estradiol benzoate (day 0). On day seven, the intravaginal device was removed, and cows were immediately intramuscularly injected with 0.150 mg of D-cloprostenol. On the following day (day eight), Kisspeptin-10 was as effective as GnRH in inducing ovulation. 56 hours after the removal of the intravaginal device (day nine), cows were intramuscularly injected with GnRH or Kisspeptin-10. Cows were assigned to four treatments: T1, 100 µg of GnRH (positive control), T2, T3, and T4 with 500 µg, 1000 µg, and 1500 µg of Kisspeptin-10, respectively. Ovulation was detected via ultrasonography four days post-treatment. The response variable evaluated was the ovulation rate. Data were analyzed using generalized linear models with a logit link function. Results. Ovulation rates obtained with T1 and T4 were statistically equal (99.9%; p>0.05) and higher (p<0.05) than those achieved with T2 (98.5%) and T3 (88.4%), with the latter two being statistically equal (p>0.05). Conclusion. Kisspeptin-10 1500 µg was as effective as GnRH in inducing ovulation.