Based on recent study results, the suspense of waiting to know a new foal’s sex could be a thing of the past: Breeders might soon be able to choose ahead of time whether they’d like a colt or a filly out of a specific mating.

As reported by Juan Samper, DVM, MSc, PhD, Dipl. ACT from JCS Veterinary Reproductive Services Ltd., in British Columbia, Canada, and colleagues, a Texas-based company (Sexing Technologies) could offer "sex-sorted stallion semen" that allows horse owners to pick the sex of their future foals. However the current system has several limitations and substantially more research is needed before the process is implemented worldwide, Samper said.

"There are many companies and patents claiming that they can alter the sex ratio of the offspring, but only a technique called high-speed flow cytometry can separate X- and Y-bearing sperm," explained Samper.

High-speed flow cytometry involves taking a fresh ejaculate and running the sample through the high-tech cell-sorting machinery, which separates the X (female) sperm from the Y (male) sperm. The resultant samples are between 90% and 95% pure, meaning that about 5% of the sorted sperm won’t produce a foal of the desired sex.

The other, bigger problem with sex sorting is that although the process is called "high speed," it still takes around two to three hours to sort enough sperm to produce one insemination dose of 20 to 40 million sperm, which is a much lower number of sperm typically used to inseminate mares.

"This requires changes in insemination techniques, such as deep horn insemination, which adds another level