Current status and prospects of the application of biotechnologies or reproduction in cattle.

摘要

The artificial insemination (AI) technology is the oldest but still the most effective reproductive technology. Actually, ~4.8 million first inseminations are carried out in Germany per year. The number of inseminations has decreased due to the increasing performance and fixed amounts of delivery for milk within the last years (2 to 4% per year). Embryo transfer was used in cattle breeding for ~25 years. The production of breeding bull calves as well as breeding of cow families is its central application. On the average, 6 to 7 transferable embryos per donor are recovered after superovulatory treatment, A. I. and embryo recovery in Holstein cattle. Approximately half of the embryos are transferred fresh whereas, the other half are deep-frozen. The cryopreservation of embryos is routinely carried out. Another reproduction biotechnology, the in vitro production of embryos, was introduced into practice. The method is to primarily shorten the generation interval. The different aspects involved in the method are continuously investigated to improve the efficiency of the technique. On the other hand, cloning technology does not have a practical significance in cattle production. The main emphasis of the application of the method is on the production of transgenic animals and the efficiency of the method is altogether low. Among the different methods of sexing embryos, the detection of Y chromosome specific DNA has gained acceptance since 1990s wherein the percentage of correct diagnoses is >90%. In the field of sperm sorting, the flow cytometric detection of the of DNA in X or Y chromosome bearing spermatozoa is currently the only reliable method. The enrichment of sperm cells with an X or Y chromosome in the appropriate groups is >90%. Only limited data about pregnancy rates after insemination of sorted spermatozoa under field conditions are available. Results show that the pregnancy rates are ~15-20% lower than the control groups.