Estrus synchronization and ovulation induction in pigs

Abstract

Background: Synchronization of estrus with artificial hormonal suppression and fixed insemination time is a promising tool in modern pig farming, which contributes to the optimization of reproductive processes, reduction of labor costs, and increase of herd productivity. At the same time, the effectiveness of this technology depends on the level of hormonal preparation of animals and the chosen synchronization protocol. Aim: The study assessed the effectiveness of modern biotechnological methods for regulating the sexual function of sows to increase their reproductive capacity and optimize reproduction in pig farming. Methods: Three hormonal protocols of estrus synchronization and ovulation induction were used in this study. Scheme A used oral administration of altrenogest for 14 days, followed by administration of eCG and hCG, and a fixed time of artificial insemination. According to scheme B, after 14 days of altrenogest use, a GnRH analog was administered to induce ovulation, followed by insemination according to the reaction time of the animals. According to scheme C, prostaglandin F2α or its analogues were used, followed by the introduction of eCG and hCG, and artificial insemination according to the unified scheme. Results: A comparison of the schemes shows that scheme A provides the highest synchronization efficiency, allowing the accurate regulation of the cycle. It ensures the highest rate of estrus expression (92%), a statistically significant increase in litter size (up to 12.1 piglets; p < 0.05), and a reduction in the inter-farrowing interval (to 153 days; p < 0.05). Scheme B is characterized by more natural stimulation, but the effect may vary depending on the animal’s physiological state. Scheme C is technologically simpler but less effective from the point of view of synchronization, especially in different post-weaning statuses of sows. Conclusion: The use of scheme A made it possible to obtain an additional nearly 11 kg of piglet live weight at weaning per sow, corresponding to an additional income of +16.98 USD per head. Particularly important is the reduction of the inter-farrowing interval by 6–13 days in the experimental groups, which increases the potential number of farrowings from 2.1 to 2.3 per year, thereby allowing the production of up to 4–5 additional piglets per sow annually.