Transport of equine ovaries for assisted reproduction

Use of assisted reproduction to obtain foals from valuable mares post-mortem typically necessitates holding of ovaries during shipment to a laboratory. The present study evaluated whether holding ovaries briefly at a warm (∼30 °C) temperature improves meiotic and developmental competence of oocytes, as determined after maturation in vitro and intracytoplasmic sperm injection. Ovaries were packaged in pairs in insulated containers, and held either at 24 or 25–35 °C for 4 h, followed by cooling. Ovaries in both treatments were held for either a short (mean, 7–7.4 h) or long (mean, 20.6–20.7 h) duration before oocyte recovery. Control ovaries were collected en masse at the abattoir. The ovary temperature in this treatment slowly decreased to ∼27 °C; oocyte recovery was performed after 3.5–7 h total holding. There was no effect of temperature on oocyte meiotic or developmental competence within either treatment time period. Oocytes in the short duration holding group had similar meiotic competence to controls, but had a significantly decreased rate (P < 0.05) of blastocyst development. Oocytes in the long duration holding group had decreased (P < 0.05) meiotic competence and blastocyst development compared to controls. These findings indicate that storage of equine ovaries for only 7 h may decrease blastocyst development, and that longer storage reduces both rate of oocyte maturation and blastocyst development. Further work is needed to determine if there is a critical time before 7 h post-mortem by which equine oocytes should be recovered to maximize developmental competence.