Postnatal consequences of assisted reproductive technologies in cattle

Experiments in mice and clinical observations in humans are indicative that adult phenotype can be altered in offspring derived from embryos that were subjected to culture or that were produced by the combination of in vitro oocyte maturation, fertilization and embryonic development (in vitro production; IVP). The most commonly observed changes are in body and organ size, growth rate, cardiovascular function and regulation of glucose homeostasis. In cattle, IVP is associated with increased birth weight and neonatal death loss but little is known about the long-term consequences of embryo technologies. Recently, postnatal characteristics were compared between females born as a result of artificial insemination, IVP using conventional semen, IVP using reverse X-sorted semen, and multiple ovulation - embryo transfer. Females born following IVP using reverse X-sorted semen produced less milk, milk fat, and milk protein than females in the other three groups, which were similar to each other. These results point out the importance of 1) examining other data sets to examine long-term impact of assisted reproductive technologies on adult physiology and performance and 2) evaluating whether use of sexed semen alters the adult phenotype when used for artificial insemination.