Ovulatory Response of Weaned Sows to an Altered Ratio of Exogenous Gonadotrophins.

Summary

# Editorial Summary Reproductive management in weaned sows relies heavily on exogenous gonadotrophin protocols to synchronise ovulation and maximise prolificacy, yet optimal dosing strategies remain incompletely defined. Researchers administered standard PG600 (400 IU eCG + 200 IU hCG), an elevated-hCG variant with an additional 200 IU dose 24 hours later, or no hormonal treatment to 33 weaned sows, then triggered final ovulation with 750 IU hCG and monitored follicular dynamics via transrectal ultrasound at seven timepoints over 60 hours. The elevated-hCG protocol (Gn800) significantly shortened the interval from final hCG injection to ovulation compared to standard PG600 (p = 0.02) and produced a higher proportion of sows with ≥9 preovulatory follicles—a marker of strong ovulatory response—relative to both PG600 and controls (p = 0.02 and 0.003 respectively). However, follicular cysts developed in sows receiving either gonadotrophin regimen, suggesting that enhanced hCG supplementation, whilst improving synchrony and follicle recruitment, may introduce an additional management consideration. For practitioners involved in breeding programmes, these findings indicate that modifying the timing and dose of hCG in standard protocols can refine reproductive outcomes, though monitoring for cyst formation remains prudent and warrants further investigation into long-term reproductive consequences.

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Key Findings

• •Gn800 treatment (PG600 + additional 200 IU hCG at 24h) shortened interval to ovulation compared to PG600 alone (p = 0.02)
• •More Gn800 sows developed ≥9 preovulatory follicles compared to PG600 (p = 0.02) and controls (p = 0.003)
• •Follicular cysts were evident in both gonadotrophin-treated groups (PG600 and Gn800)
• •Altered ratio of exogenous gonadotrophins modified ovulatory response in weaned sows

Conditions Studied

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