Abstract: With the development of the global horse industry, the economic value of horses is growing. Assisted reproductive technology is beneficial to dig out the potential value of excellent equine, and in vitro maturation (IVM) of horse oocytes is an important part of assisted reproductive technology. Oocyte recovery is a preparation for in vitro maturation, for the isolated ovary, more oocytes can be obtained by using the scraping method. To obtain oocytes continuously for a long time and to protect the development ability of oocytes, ovum pick up (OPU) is widely used in mare. The maturation rate of expanded oocytes is higher than that of compact oocytes, and the age of the mares affects the quality of their oocytes. Horse oocytes stored in vitro for a long time will not affect their developmental ability, there are mature systems that can keep horse oocytes in vitro for more than 24 hours without affecting their maturation rate. The basic culture medium commonly used in horse oocyte maturation system is M199, and the addition of FBS, FSH, LH, IGF-1 and other substances can significantly improve the maturation rate, and the commonly used culture environment is 38-39℃, 5% CO₂ and saturated humidity incubate for 30 hours. Mature oocytes have dilated cumulus cells and polar body, and the cytoskeleton and microtubule structure of oocytes will be changed after maturation. This review summarized the research on the collection and in vitro maturation of equine oocytes, focusing on the recovery rate of different collection techniques and some key factors affecting the in vitro maturation rate of equine oocytes, in order to provide some knowledge and experience for further research of IVM and in vitro fertilization (IVF) in the future.

Key words: horse, oocytes, recovery, in vitro maturation