Ovarian storage time and semen source do not affect IVF outcome in domestic cats (Felis catus), but reproductive season does.

The domestic cat (Felis catus) provides a valuable model for developing assisted reproductive technologies (ART) that can be applied to the conservation of endangered wild felids. A major limitation in the application of ART is the restricted availability and transport of high-quality gametes. This study investigated the effect of ovarian storage duration, semen source, and season on in vitro maturation (IVM), fertilization (IVF), and embryo development in the domestic cat. Ovaries collected after routine ovariohysterectomy were stored at 4 °C for either ≤ 10 h (short storage) or 11-30 h (long storage). Oocytes were fertilized using epididymal semen, urethral semen, or cryopreserved epididymal semen. A total of 666 oocytes were evaluated. Multivariable regression analysis revealed no significant effect of storage duration on oocyte maturation or subsequent embryo development. In contrast, season was identified as a major determinant of both IVM and IVF outcomes, with oocytes collected during the breeding season (February-April) showing a significantly higher probability of maturation and embryo formation compared with the pre-breeding season (December-January). Semen type significantly influenced embryo formation following IVF, with higher embryo rates observed when epididymal semen was used, whereas no significant effect was observed for cryopreserved semen. Blastocyst formation remained low and was not significantly affected by storage duration or season. These findings indicate that cat oocytes retain meiotic and developmental competence for up to 30 h of ovarian storage at 4 °C, while seasonal factors exert the strongest influence on reproductive outcomes, and semen source may affect early embryo development under in vitro conditions.