Superovulation in cattle: practical aspects of gonadotropin treatment and insemination.

Embryo transfer (ET) in cattle has been used for the realisation of breeding programmes world-wide for more than 20 years. The efficiency of breeding technology, i.e. the breeding progress and costs, depends to a large extent on the results of superovulatory treatment and artificial insemination (A.I.). The results of this step are characterised by a high degree of variation. Numerous attempts have been undertaken to explain the reason(s) for this. Numerous attempts have also been made to clarify the importance of different factors affecting the results. Undoubtedly, the applied hormones and the scheme of insemination itself are main factors, which influence the number and the portion of transferable embryos. Therefore this paper is focused on the following aspects of superovulatory treatment with FSH: dose-response relations, bioactivity of the glycoprotein, FSH/LH ratio, ovulation time and time-oriented insemination, frequency of gonadotropin administration and follicular population at the time of gonadotropin application.