Embryo development rates after transfer of oocytes matured in vivo, in vitro, or within oviducts of mares.

This research study aimed to compare the developmental capacity of horse oocytes collected from living mares versus those gathered from slaughterhouse ovaries. Additionally, it examined the viability between in vivo, in vitro, or oviduct-matured oocytes. Results showed that in vivo matured oocytes had a higher rate of embryo development compared to in vitro or oviduct-grown oocytes.

Objectives and Methodology

• The study had two primary objectives: to compare the developmental ability of oocytes collected from ovaries of live mares with those gathered from slaughterhouse ovaries, and to compare the oocytes’ viability depending on whether they matured in vivo, in vitro, or in the oviduct.
• Oocytes were collected by a process called transvaginal, ultrasound-guided follicular aspiration (TVA) from live mares, or from slicing ovaries procured from a slaughterhouse.
• Four distinct groups of oocytes were transferred into recipient oviducts and inseminated. These groups included oocytes matured in vivo and collected via TVA, immature oocytes collected via TVA and matured in vitro, immature oocytes collected via TVA and transferred into a recipient’s oviduct shortly after collection, and immature oocytes gathered from slaughterhouse ovaries and matured in vitro.

Findings and Conclusions

• The study found that embryo development rates were significantly higher for oocytes matured in vivo (82%) than for those matured in vitro (9%) or in the oviduct (0%).
• However, the method of maturation or the source of the oocytes did not significantly impact embryo development rates after the transfer of immature oocytes, suggesting that the maturation environment doesn’t affect the development of immature oocytes after their transfer.
• The superior performance of the in vivo matured oocytes indicates a potentially preferable method for horse breeding purposes, as it allows for a higher embryo development rate.