Abstract: In order to study the effect of effective sperm quantity on the pregnancy rate of Jilin mares during estrus, 300 healthy Jilin mares with the normal estrus cycle were selected for the experiment in 2018—2020. Jilin mares were inseminated by conventional insemination of uterine body, insemination in deep uterine horn and different effective sperm quantity. The results showed that when the number of effective sperms was more than 2×10⁸ with conventional insemination of uterine body or the number of effective sperms was more 0.5×10⁸ with deep uterine horn insemination, the conception rate of Jilin mares in estrus could reach more than 60.00%. The average conception rate in estrus of Jilin mares with deep uterine horn insemination was 69.80%, and that of Jilin mares with conventional uterine body insemination was 45.78%, the difference was very significant （P<0.01）. It indicated that deep uterine horn insemination could significantly improve the conception rate of Jilin mare during estrus, significantly reduce the number of effective sperms per insemination, and improve the utilization efficiency of male semen.

Key words: Jilin horse, artificial insemination, insemination mode, effective sperm number, estrus conception rate