Sexed semen can be produced using a flow cytometry and sorting process or via another process that selectively destroys sperm cells carrying the undesired chromosome. With about 90% accuracy, sexed semen allows producers to effectively choose whether a mating results in a bull or heifer calf. That gives you an opportunity to either skew the sex ratio of the entire calf crop or selectively produce heifer or bull calves from specific planned matings within the herd. 

Why would you use it?

Although sexed semen has been widely available to the dairy industry now for years, recent changes have allowed this reproductive technology to become a real opportunity for beef producers. The decision to use sexed semen really comes down to economics: There has to be a value difference between the sexes of calves. If that value difference is large enough, and the costs are low enough, using sex-sorted semen is a profitable opportunity that should be considered. There is more to the question than just consideration of the market price of steer calves versus heifer calves, however; there may be benefits and costs you don’t immediately think of. For example, for years, producers have recognized the advantage of using calving-ease sires on heifers to minimize calving difficulty. Sex-sorted semen adds another opportunity, in that heifers could also be inseminated with X-bearing sperm to produce heifer calves. With heifers calving light-weight heifer calves, incidence of calving difficulty is further reduced. Sometimes, providing information to buyers also has value in and of itself. For example, you may be able to capture a premium if selling lots of heifers with known-sex pregnancies. Depending on the scale of your operation, sexed semen may allow you to produce a certain quantity of steer calves, offer a more uniform set and command a better price. A 50,000 pound pot load of A.I.-sired, half-sibling steers of the same age from a single point of origin – that sounds like a pretty hot commodity for a feeder.

Can any bull’s semen be sexed?

Sex-sorted semen is now available on more beef sires than ever before, and research programs continue to result in better strategies to use sex-sorted semen effectively. However, each individual bull is different when it comes to the success of sex-sorting sperm cells. One bull’s sperm cells may be able to be collected and frozen successfully as conventional semen, but unsuccessfully when it comes to sexed semen. Companies that offer sexed semen continually collect conception data from herds that use sexed semen in order to assess fertility and identify bulls that are underperforming. Identifying bulls with high and low fertility after sex-sorting is an exciting area for further research, and we will likely allow the expansion of beef bulls used for sexed semen in the future.

What are the disadvantages?

Due to the sexing procedure and freezing of those sperm cells, expect sexed semen to result in somewhat lower pregnancy rates than conventional semen. Pregnancy rates with sexed semen are typically 10% to 20% lower than pregnancy rates with conventional semen. Sexed semen will also cost more per unit than conventional semen, often $15-25 more depending on the sire used. A higher cost per unit for a lower pregnancy rate means a higher cost per pregnancy.

How do you use sexed semen?

For the best pregnancy rates with sexed semen, research suggests insemination should be performed roughly 18-24 hours after onset of standing estrus. Of course, most beef producers want to use a timed A.I. protocol rather than performing heat detection. At the University of Missouri, we have worked extensively to develop timed A.I. approaches for beef cows and heifers that result in strong pregnancy rates with sexed semen. Reach out to us for specific recommendations, but as a general rule, animals that express estrus prior to timed A.I. are the best candidates for use of sex-sorted semen. Consider using an estrus detection aid (e.g., Estrotect breeding indicators) and restricting use of sex-sorted semen to only those with activated patches. Conventional semen could be used for the remainder of the animals. If you want to inseminate as many animals as possible with sex-sorted semen, you may want to consider using the split-time A.I. procedure we developed. When using that approach, animals that have not expressed estrus prior to the timed A.I. event are sorted off and bred 24 hours later. At that time, you may choose to use sex-sorted semen on the proportion of those animals that have now expressed estrus.

What is next for sexed semen?

The coming years will undoubtedly offer continued improvements with sexed semen, and there is clearly a potential place for sex-sorted semen in the commercial beef industry. Whether your goal is to quickly turn over females in the herd with superior genetics, produce elite animals to market as herd bulls or replacement heifers, or simply produce a greater quantity and quality of feeder cattle, sexed semen is a tool to have on your radar. It won’t pencil out in every case, but it is time to put the pencil to it.  

Illustration by Kristen Phillips.

Carson Andersen is a graduate research assistant at the University of Missouri – Division of Animal Sciences.

Jordan Thomas, Ph.D. is an assistant extension professor and state beef reproduction specialist at the University of Missouri – Division of Animal Sciences.