A Comparative Study Of Natural Ovulation And Induced Ovulation In Mongolian Mares

As one of the common representatives of the genus Equus,horses have ovarian structures and follicle development patterns that are different from most mammals.The ovarian structure of most mammals has the cortex outside and the medulla inside,and can release eggs at all sites on the surface of the ovary.However,the ovary structure of horses is outside the medulla and inside the cortex,and only the ovary can be used for ovulation on the surface of the ovary.Due to space limitations,only one egg can be released at a time.This fundamental difference prevents mature modern breeding techniques such as superovulation,which are widely used in other animal breeding,from being achievable in the equine species.Our team has determined in the practice of horse farms that another technology that is also ovulation control technology-ovulation stimulation technology has a certain effect in promoting ovulation in horses.Therefore,we hope that through this study,we will first use histological methods to clarify On the basis of the ovarian structure of Mongolian horses and the developmental patterns of follicles in different periods,10 Mongolian horses were then subjected to a round of natural ovulation and human chorionic gonadotropin(hCG)-mediated ovulation promotion respectively,and the follicle diameter of Mongolian horses was 35 mm.In order to evaluate the effect of hCG on follicular development,ovulation and conception rate of Mongolian horses,the difference between natural ovulation and ovulation induction in Mongolian horses was determined.A means to provide a theoretical basis.The main results we obtained are:1.The follicle development of Mongolian horses may have a certain direction due to the existence of the ovulatory fossa.In the follicular stage ovary,follicles in different developmental stages can be crossed in different planes,and the follicle structure is the same as that in other animals.2.When the follicle diameter of Mongolian horse developed to about 35 mm,hCG treatment was used,and compared with the naturally developed follicle,it was found that the difference in the development of follicle diameter between the two groups was not obvious within 0h,24,and 48 h.When the follicle diameter was about 35 mm,the injection of hCG had no obvious effect on follicle development.3.After using hormones on follicles with a diameter of about 35 mm in Mongolian horses,it was found that after a single injection of 2000IU/hCG,the ovulation rates of mares in the ovulation induction group were 20%,50%,and 30% within 24 h,48h,and 72 h,respectively.The ovulation time is mainly concentrated in 48 h.However,the ovulation rates of mares within the same follicle diameter within 24 h,48h,72 h,and 96 h were 0%,0%,70%,and 30%,respectively.It can be known that the ovulation time is concentrated in 72 h.It shows that the use of hormone induction can make the Mongolian horse’s follicle ovulation highly concentrated within 48 h,which confirms that the mare has an obvious response to hCG treatment.4.Through the research on the side of ovarian dominant follicle development in two Mongolian horses,it was found that in the hCG-treated ovulation stimulation group,the probability of the ovarian development side of the dominant follicle was the same.In the spontaneous group,the number of dominant follicles in the right ovary was higher than that in the left ovary.However,there is no difference in fertility after ovulation of the dominant follicle in the left and right ovaries.5.When the follicle diameter reached about 35 mm,the conception rate of Mongolian horses in the self-fertilization group was higher than that in the induced-ovulation group,reaching 75%.In contrast,the conception rate of the stimulation group injected with2000IU/hCG was 68%.The results showed that the use of hCG did not improve the conception rate of Mongolian horses.6.Our research has proved that intramuscular injection of 2000IU/hCG to the follicles of Mongolian horses with a diameter of 35 mm during the estrus season will accelerate the ovulation speed of the dominant follicles and effectively concentrate the ovulation time period.The issue of horse reproductive efficiency requires further in-depth research on more horses,including the effect of hCG-accelerated ovulation on the maturation of horse oocytes,in order to explore the fact that the conception rate of the stimulated ovulation group is lower than that of the spontaneous ovulation group.the cause of the result.