Efeito do tratamento com gonadotrofinas sobre o trato reprodutivo e ciclo estral de leitoas

Abstract

The early and efficient onset of puberty in gilts is essential to ensure their reproductive longevity and productivity within production systems. The maturation of the hypothalamic-pituitary-gonadal (HPG) axis, mediated by the action of hormones such as GnRH, LH, and FSH, depends on the activation of neuroendocrine pathways, including the kisspeptin/GPR54 system. Failure to reach puberty, which occurs in up to 30% of gilts, may be associated with neurobiological and environmental factors, negatively impacting reproductive performance. The estrous cycle in sows, with an average duration of 21 days, is regulated by hormonal and structural changes in the ovaries and is divided into follicular and luteal phases. Given the challenges of natural estrus synchronization, the use of exogenous hormones—such as progestagens, estrogens, and gonadotropins—has proven to be a valuable tool for reproductive organization and herd management, particularly in production systems based on batch management. The proper selection and application of these hormonal protocols contribute to resource optimization, production predictability, and improved reproductive indicators. In the present study, two separate experiments were conducted in pubertal females treated with exogenous gonadotropins. In the first, two doses of 1500 IU of hCG were administered on days 12 and 15, followed by the application of sodium cloprostenol on days 25 and 30. In the second experiment, females received eCG on day 10, hCG on day 12, and two additional doses of hCG as in the previous experiment, with cloprostenol administered only on day 30. The injection of sodium cloprostenol on day 30 was able to reduce progesterone concentrations and concentrate estrus expression in most females within six days after administration. However, in the second experiment, the group that received the two doses of hCG showed a significant reduction in litter size compared to the control and eCG + hCG groups. Lastly, prepubertal females were hormonally treated with gonadotropins to mimic different phases of the estrous cycle, with one group being inseminated. In these females, a morphometric evaluation of the oviducts was performed across the different groups. No significant differences were observed between groups in the measurements of the uterine tube segments evaluated.