The influence of hormonal interference on pregnancy rate in recipient cows

The article presents recent opinions concerning the efficiency, time-period , forms of application anti reasons for biotechnical manipulations which in volve supplementing cows with hormones such as progesterone, GnRH and hCC. A number of opinions confirm the positive influence these substances have o n pregnancy results in cases where they are applied directly after embryo t ransfer. Other data, however, indicate that there is no correlation between hormone supplements and pregnancy results, The influence of factors such a s heat synchronisation, quality of embryo and/or its development stage have a greater influence on pregnancy rate than hormone application.