Effectiveness of embryo transfer in cows - risk factors including in vivo derived and in vitro produced embryos

Abstract Multiple Ovulation Embryo Transfer is a biotech method with more than 50 years of history and an established position in cattle breeding. This procedure is beneficial in many ways, but it also carries a risk of failure. The study presents the overview of the most important risk factors that may affect conception rates in the course of embryo transfer, including the factors associated with the embryo sourcing (embryo production method, embryo quality, development stage and breed, embryo storage method), embryo transfer procedure (synchrony/asynchrony, embryo transfer difficulty, the time of the transcervical insemination gun passage, depth of embryo deposition, localization and structure of the corpus luteum relative to the follicle and both individual characteristics of donors and recipients (level of concentration of progesterone, the state of health of the udder, lactation level, body condition score and age) and some environmental factors.