Induced ovulation and conception in locating sows

Area of Science:

• Veterinary Medicine
• Animal Reproduction
• Endocrinology

Background:

• Lactating sows typically have a prolonged interval between farrowings due to anestrus.
• Early weaning is often employed to re-establish estrus, impacting piglet welfare and production efficiency.
• Hormonal interventions offer a potential strategy to synchronize estrus and ovulation in lactating sows.

Purpose of the Study:

• To evaluate the efficacy of a pregnant mare serum gonadotrophin (PMSG) and human chorionic gonadotrophin (HCG) treatment regimen for inducing ovulation and conception in lactating sows.
• To determine the optimal timing postpartum for administering PMSG/HCG treatment to maximize pregnancy rates.
• To assess the impact of prostaglandin F2 alpha (PGF2 alpha) pretreatment on reproductive parameters.

Main Methods:

• Experiment 1: Lactating sows received PMSG, followed by PGF2 alpha (in some) and HCG, with timed artificial insemination.
• Experiment 2: PMSG/HCG treatments were administered at different postpartum intervals (days 5, 10, 15, 20).
• Experiment 3: Ovarian response to PMSG/HCG was assessed via laparotomy at 5 and 10 days postpartum.

Main Results:

• PMSG/HCG treatment resulted in successful pregnancies in lactating sows, with conception rates of 85% and 77% in sows allowed to complete gestation.
• Pregnancy rates increased significantly when PMSG/HCG treatment was initiated on day 10 (2/10), day 15 (8/10), and day 20 (6/10) postpartum, compared to day 5 (0/10).
• Ovarian response was minimal at day 5 postpartum but showed a 43% ovulation rate by day 10, suggesting improved responsiveness with delayed treatment.

Conclusions:

• The PMSG/HCG hormonal protocol effectively induces ovulation and conception in lactating sows, with optimal results when initiated around 15 days postpartum.
• This approach enables concurrent lactation and gestation, potentially reducing the interval between successive farrowings and eliminating the need for early weaning.
• PGF2 alpha pretreatment did not influence conception rates or other reproductive parameters in this study.