Drastically lower prices would seem likely if it works as advertised Sexed semen has only been on the market for a handful of years, but has already become a familiar, although not necessarily widespread, tool in the dairy industry. Higher cost and lower fertility are still barriers for many milk producers, but those could be blasted down by a breakthrough sexed semen sorting process that a Canadian firm says it has made. Toronto-based Microbix Biosystems says it has developed a new way to sort X chromosome cells (female) from Y chromosome cells (male) that on paper looks like it would slash the price of sexed semen. If true, it could also change the face of milk production by drastically altering the ratio of heifers and bulls that are born. Current semen sorting technology involves moving sperm cells in a fluid stream at high velocity in front of a detection laser to examine each individual cell. Unwanted Y chromosomes are removed by high-pressure fluid squirts - a process that is both slow and damaging to many of the X cells. As a result, the yield of usable sexed semen is much lower than with conventional semen packaging. Conception rate in animals receiving it is also about one-third lower, due to abuse suffered by the remaining semen. Thus, sexed semen is expensive and tends to be used in limited quantities by producers who choose to use it at all. Microbix says its new process uses a laser to "zap" the male Y chromosomes as they flow by, which speeds up the sorting process by10 times or more, nearly eliminates damage to female X chromosomes, and yields 2.5 times more usable sperm. Conception rates of the sexed semen, it says, are nearly equal to that of conventional semen.