Attempts to explain and reduce variability of superovulation

The variability in response to superovulation treatment is a major disadvantage for economical use of embryo transfer and clearly limits use of embryo transfer in animal breeding. Despite considerable efforts, it has not yet been possible to reduce this variability drastically. Less than 40% of the causes for variability has been explained to date. The high proportion of unexplained variability leads to the hypothesis that variability is a special biological function that supports natural selection over the long term. Corresponding data from laboratory animal studies support this hypothesis.