| Evaluating iterative superovulation on highbred cow to obtain abundant useable embryo, one of effective ways to speed up fine strain breeding Carrying out sex identification on early embryo with suitable method may enhance the producing benefits of Embryo transfer greatly Take the Holstein cattle and its embryo as test materials, carrying repeated superovulation treatment with FSH + Estrumate and CIDR + FSH +PGF2a separately, then give early sex identification experiment on obtained embryos use LAMP.(1) Divides 52 Holstein cattle of 13~15 months years old into group A and B stochastically, then carrying duplicative superovulation treatment with FSH + Estrumate and CIDR + FSH + PGF2a separately. There are 4 superovulations every year in Group A, 28. 99 available embryos per head are attained, avergae 7.25 useable embryos each time. In contrast, There are 8 superovulations every year in Group B, 34. 06 available embryos per head are attained, average 4. 33 useable embryos each time, and in last 4 superovulations, average2. 28 useable embryos a time.(2) Take sex identification and the embryo transfer experiments on different quality embryos (blastocyst and morula;fresh embryo and the frozen embryo) with FSH method respectively, and then checkout their sex determinate rate and fertility rate. Results suggest, blastocyst, morula, fresh embryo and the frozen embryo in grade A all have 100% sex determinate rate, grade B and grade C all reach 96%. The conception rate of Blastocyst and morula in grade A is 44%, 26. 9%. In contrast, grade B are 36% and 16. 7%, and grade C only can reach 20% and 8%. After identification on fresh embryos and frozen embryos , their transplant conception rate is 45. 5% and33. 3%, that show the quality have faint influence on sex determination rate by LAMP method, but evident influence on conception rate. We can find blastocyst' s rate is higher than morula' s. From grade A to grand C, the rates descend, and fresh embryo is better than frozen one.(3) Deal with the blastocyst , which identified by LAMP method , in vitro culture rank 0, 1, 2, 3, 4, 7hour. After the graftage, we find their conception rate is 25%, 41. 7%, 54. 2%, 50. 0%, 25. 8%, 12. 8% separately. That indict l~3h is a suitable time for biopsied. Transplant immediately or wait too long time all are adverse to implantation.This research consider it is feasible to attain abundant available embryos through repeated superovulation , and four time a year is suitable. The fourth and later superovulations may begin in fall or winter. Influenced by season and repeated superovulations, donor' s physical condition begin to drop. Continued repeated superovulations with same drag, donor' s sensibility begin to drop. Simultaneously , immune body are produced in vivo, secretion level of FSH drop, then the ovulation number reduces, follicle' s growth are hindered, and ova's fertilization ability and the embryonic development situation all reduce in same time, therefore, flush embryos and usable embryo' s number all are down.Carrying early embryo sex appraisal with the LAMP , is a method have the advantages of high accuracy and simplicity. In the embryos identified , blastocyst and fresh embryo have high conception rate, and morula, frozen embryo , and lower grade embryo have lower rate. We also find, l~3h is a suitable time for transplant. Transplant immediately or cultivate more than 3h all are adverse to conception rate.
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