Evolution of cervine, caprine and ovine sex-sorted semen processing

It has been three decades since the first publication showing that flow cytometry was a reliable method to separate X and Y chromosome bearing sperm based on their difference in DNA content (Johnson et al., 1989). Ten years after that publication, the first commercial straw containing 2.1 x 106 frozen sex-sorted bovine sperm was released to the market for standard artificial insemination (Garner and Seidel, 2008). Several improvements have happened in the flow cytometry technology since that first commercial straw was released, such as the introduction of orienting nozzles, digital processing, multiple headed sorters, and automation, in a new generation of faster and more efficient sperm sorters known as Genesis (Sharpe and Evans, 2009; Evans, 2010). Significant enhancements in sperm handling, preparation for sorting and media composition have also allowed for sperm quality and conception rates of sex-sorted sperm to reach levels that are comparable with non-sorted (conventional) semen (Vishwanath et al., 2014; Vishwanath, 2014; González-Marín et al., 2018; de Graaf et al., 2014). The result is a complete overhaul of the conditions under which sperm is processed and sorted, known commercially as SexedULTRA™ ...