Sex selection of sperm in farm animals: status report and developmental prospects.

Pre-selection of spermatozoa based on the relative DNA difference between X- and Y-chromosome bearing populations by flow cytometry is an established method that has been introduced into commercial cattle production. Although several important improvements have increased the sort efficiency, the fertilising ability of sexed spermatozoa based on offspring per insemination is still behind farmers' expectations. The main stress factors, especially on mitochondria, that reduce the lifespan of spermatozoa are described, and new technical as well as biological solutions to maintain the natural sperm integrity and to increase the sorting efficiency are discussed.

Improved quality of sex-sorted sperm: a prerequisite for wider commercial application.

To date the only successful method to sort sperm into X- and Y-chromosome-bearing populations is the Beltsville Sperm Sexing Technology. Fertility results continue to be variable even though the technology has been used in a commercial setting for nearly a decade. This is at least partly due to the reduced lifespan of sperm after sorting and freezing.