Application of sex-selected semen in heifer development and breeding programs

The only practicable method for sexing mammalian sperm is by measuring DNA content with a flow cytometer/cell sorter. Although many other methods have been tried and patented, they either are inaccurate, damage sperm severely, or otherwise are unsuitable for practical application. Procedures for sexing sperm damage them slightly, and fewer sperm are packaged per straw than with unsexed semen. These 2 characteristics result in lower fertility with sexed than unsexed semen. Incremental improvements of current sexing procedures are being developed constantly.