I didn't believe you, but: > The method works by staining sperm with a DNA-binding fluorescent dye. The bovine Y-chromosome-bearing sperm contain 3.8% less DNA

I didn't believe you, but: > The method works by staining sperm with a DNA-binding fluorescent dye. The bovine Y-chromosome-bearing sperm contain 3.8% less DNA than the X-chromosome-bearing sperm. Because of the dye, the male and female sperm can be electrically charged differently. This allows for their separation by a fluorescence-activated cell sorter (Seidel, 2007). The method is fairly accurate with ~90% of the sperm containing the desired sex (Garner and Seidel, 2003; DeJarnette et al., 2008). Sexed semen will contain a lower concentration of sperm per straw (approximately 2 million) than non-sexed semen (approximately 20 million) because the sorting process is relatively slow. Because of lower doses of sperm per straw, and possibly a negative effect of the sorting process, fertility of sexed sperm is typically lower compared with conventional sperm (Garner and Seidel, 2003; DeJarnette et al., 2008).[1] 1. https://dairy-cattle.extension.org/the-economics-of-sexed-semen-in-dairy-heifers-and-cows/#:~:text=The%20goal%20with%20sexed%20semen,(and%20better)%20heifer%20calves.&text=With%20heifers%20(and%20cows)%2C,typically%20not%20for%20later%20breedings https://dairy-cattle.extension.org/the-economics-of-sexed-se....