Superovulation with eCG alone or combined with the GnRH analogue buserelin improves transferable embryo production in weaned sows without affecting day 6 embryo morphological, cellular, and transcriptomic parameters.
Both eCG alone and eCG combined with buserelin significantly improve embryo production in weaned sows without compromising embryo quality.
Where it sits
this study against the rest of the buserelin corpusSummary and findings
This study measured the effects of eCG alone and eCG combined with buserelin on embryo production in multiparous weaned sows. The doses used were 1000 IU of eCG and 10 µg of buserelin at estrus onset. Both hormonal treatments increased ovulatory response and transferable embryo production efficiency compared to controls.
Abstract
Efficient superovulation protocols are essential to improve efficiency and facilitate scheduling in porcine embryo transfer (ET) programs. Although hCG is widely used to synchronize ovulation following eCG-based superovulation, constraints in its availability have highlighted the need for hCG-free strategies. GnRH agonists could expand ovulation induction options within eCG-based superovulation protocols. In this study, multiparous weaned donor sows received eCG alone (1000 IU, 24 h post-weaning), eCG plus buserelin, a GnRH agonist (10 µg at estrus onset), or no hormonal treatment (control), and embryos were recovered on Day 6 after estrus to evaluate ovulatory response, embryo production efficiency, developmental synchrony, and blastocyst transcriptomic profiles. Both hormonal protocols independently increased ovulatory response by approximately 48% (~37 vs 25 corpora lutea; P < 0.001) and doubled transferable embryo production efficiency compared with controls (P < 0.001), without affecting pregnancy and fertilization rates, embryonic viability, total cell number, or apoptosis. Untreated sows showed the greatest developmental dispersion and a higher proportion of hatched blastocysts, whereas eCG-treated sows showed intermediate variability. The addition of buserelin further improved ovulation-embryo synchrony, with most embryos at the blastocyst stage and all viable embryos classified as transferable. Transcriptomic profiling identified a limited number of differentially expressed genes between treated and control embryos. In conclusion, both hCG-free treatments increased embryo production in weaned sows without adversely affecting the Day-6 blastocyst quality parameters assessed, whereas the addition of buserelin further improved embryo-stage synchrony at collection. Overall, both protocols represent practical hCG-free strategies for in vivo porcine embryo production under commercial conditions.
Background
The study addresses the need for efficient superovulation protocols in porcine embryo transfer programs, particularly in light of constraints on hCG availability. Previous methods often relied on hCG to synchronize ovulation, which has prompted exploration of alternatives such as GnRH agonists. This research is significant as it evaluates the effectiveness of buserelin in combination with eCG, potentially offering a viable hCG-free option for embryo production.
Methods
Multiparous weaned donor sows were assigned to receive either eCG alone (1000 IU, 24 hours post-weaning), eCG plus buserelin (10 µg at estrus onset), or no hormonal treatment (control). Embryos were recovered on Day 6 after estrus to assess ovulatory response, embryo production efficiency, and developmental parameters. The study design appears to be a controlled experimental setup.
Results
The primary endpoint showed an approximately 48% increase in ovulatory response with the hormonal treatments (P < 0.001). Transferable embryo production efficiency also doubled compared to controls (P < 0.001). No significant differences were noted in pregnancy rates, fertilization rates, or other embryo quality metrics.
Interpretation
The findings suggest that both hormonal treatments significantly enhance embryo production compared to controls, aligning with previous literature that supports the use of eCG in superovulation. However, the clinical significance of the increase in ovulatory response and embryo production efficiency should be considered in the context of practical applications. Limitations such as the lack of long-term follow-up and potential confounding factors in the study design may affect the robustness of the conclusions.
Key findings
- Approximately 48% increase in ovulatory response (~37 vs 25 corpora lutea; P < 0.001).
- Doubling of transferable embryo production efficiency compared with controls (P < 0.001).
- No adverse effects on pregnancy and fertilization rates, embryonic viability, total cell number, or apoptosis.
- Most embryos at the blastocyst stage with all viable embryos classified as transferable.
Limitations
- Not reported in abstract.