Optimizing IVF with sexed sperm in cattle.

Sperm-sorting by flow cytometry separates X-sperm from Y-sperm with an accuracy as high as 90% or more. This technology offers farmers and the livestock industry the potential to nearly double productivity, by producing the desired sex to optimize breeding programs. Sorting speed and fertility variation of sorted sperm, however, remain limiting factors for widespread application, particularly in traditional AI programs. Alternatively, in vitro fertilization is a feasible and efficient means to increase the fertilization efficiency of sex-sorted sperm in cattle. Procedures to increase fertilization rate and improve embryo quality include optimizing heparin concentrations for semen of each bull, reducing fertilization drop size to increase sperm concentration, use of fructose instead of glucose in culture media, and use of vitrification protocols with extremely rapid cooling and warming rates.