The Research To Improve Mare Conception Rate By Inducing Ovulation

Although early studies on mammalian artificial insemination(AI)were carried out in equid,and at the end of the 19 th century,it is not so successful as cattle and other domestic animal.The reason is the different structure between equids and other kind of domestic animals such as cattle,sheep and sow,Most surface of the equid’s ovary is covered by stroma except the area of ovulation fossa,where is covered by ovarian cortex and follicle give ovulation from.Therefore the equids ’ estrus duration and the ovulation time changes significantly.Which make it very difficult to estimate the time to give insemination,lead to low conception rate in an oestrous cycle.In order to improve mare conception rate,especially the conception rate of artificial insemination with frozen semen,the experiment of induced ovulation had been done in Qingdao and Ili Kazak Autonomous Prefecture during breeding season.104 mares were separated in 5 groups randomly,all animals were checked once a day by ultrasonic image.When the dominant follicle diameter reached 35 mm,animal in experiment group 1(E1,7 Mares)and experiment group 2(E2,13 Mares)was injected intramuscularly with 3000 IU HCG and 400 IU LH dissolved in 5ml saline,respectively,animals in control group(C,13Mares)were injected intramuscularly with 5ml saline.Others were not be treated until the dominant follicle diameter reached 40 mm,when the dominant follicle diameter reached40 mm,separated in another 3 groups randomly,animal in experiment group 1(E1,35 Mares)and experiment group 2(E2,13 Mares)was injected intramuscularly with 3000 IU HCG and400 IU LH dissolved in 5ml saline,respectively,animals in control group(C,23 Mares).The animals were checked every 8 hours after treatment until the dominant follicle ovulated.When the ovulation was found,the mare was given artificial insemination(AI)with frozen semen straw.In order to found out the optimal dosage for AI,8,4,3and 2 straws were selected to gave insemination randomly.15 days after AI,mares were given pregnant diagnosis by ultrasonic image.The result was compared with historical record conception rate by fresh semen AI.The result show the distribution of ovulation was focus on 32 hours to 48 hours aftertreatment at the time when follicular diameter reached 40 mm with HCG or LH,The concentration degree of the treatment at the time when follicular diameter reached 40 mm with HCG or LH is 91.4% which is much better than treated at the time when follicular diameter reached 35 mm.There is no significant difference between the conception rate inseminated with fesh semen and inseminated with frozen semen after Ovulation treated by HCG or LH(P>0.05),and the effect of dosage for AI is not obvious(P>0.05),which means that the main effect of AI conception rate of mare is the AI time.In the experiment we also found that the transportation after AI would affect mare conception rate signaficently(P<0.05),and lead to pregnancy failure during early pregnancy.