Estrus induction and synchronization in gilts and sows of HD-K75 pig variety

Abstract

Studying estrus synchronization in a new variety of crossbred pigs is crucial for improving reproductive efficiency through fixed-time artificial insemination, which allows for coordinated breeding, genetic improvements with a reduced production cost. The present study evaluated the estrus synchronization protocols in gilts/sows of a crossbred pig variety (HD-K75). The gilts were assigned to two treatment groups and a control, while the sows were assigned to a control and a treatment group. The T1 group, which received 300 IU of PMSG + 100 IU hCG, gilts did not responded to treatment. On the contrary, all gilts from the T2 group, which received 400 IU PMSG + 180 IU hCG had exhibited estrus on day 7 post-treatment. Animals manifested unmistakable vulvar changes, active interaction with boars and a distinct standing reflex. Their plasma estradiol increased abruptly before estrus, followed by a rise in progesterone, suggesting normal ovulation and luteal development. PGF2α treatment at weaning, followed by 500 IU hCG at 24 h later, resulted in tightly synchronized estrous expression at approximately 42 h following hCG injection in sows. Behavioral manifestations were strong and consistent and hormonal profiles supported timely follicular growth and ovulation. Control pigs showed poor manifestation of estrus and a lack of synchronization. Results thus showed that higher amounts of gonadotropins are required to induce estrus consistently in gilts, while PGF2α and hCG in combination can induce coordinated estrus in weaned sows. These protocols are feasible for enhancing the reproductive performance of HD-K75 pig variety.