Potential for Beef Industry Use of
Gender-sorted Semen is Growing
A $200 marketing advantage for one gender over another may be sufficient to encourage use of gender-sorted semen in the beef industry.
by Troy Smith for Angus Journal
STAUNTON, Va. (Oct. 16, 2013) — Whether you call it gender-selected, sex-sorted or just sexed semen, University of Idaho animal scientist John Hall says he believes it is a technology that will see increased use among commercial cow-calf producers. It probably won’t happen right away. Speaking at the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium hosted Oct. 15-16 in Staunton, Va., Hall said artificial insemination (AI) with sexed semen has much potential, but the technology has limitations, and its application can be challenging.
Under current conditions, an average premium of $200 per head is required to provide a sufficient marketing advantage to warrant the use of gender-sorted semen, said the John Hall, University of Idaho.
While the ability to select calf gender was more readily embraced by the dairy industry, Hall said adoption by the beef industry remains slow. The number of beef sires for which sexed semen is available has grown. However, the genetic diversity accessible through sexed semen remains low compared to the use of conventional semen. For one reason, sexed semen costs more. There are also challenges to its application.
Hall said sexed semen research involving beef cattle remains somewhat limited. Results of heifer research are consistent with studies in dairy heifers that indicate a 10%-20% decrease in AI conception rates with sexed semen compared to conventional semen.
The dairy experience has discouraged use of sexed semen in fixed-time AI, which is becoming an increasingly popular application of AI for mature beef cows. Hall said beef cow research suggests using sexed semen after detected estrus is best, but fixed-time AI is feasible. Generally, there is a 10%-20% decrease in pregnancy rates compared to conventional semen, with greater variability in success.
Several factors affect success rates. Hall said cows or heifers that are inseminated based on estrus or exhibit estrus before fixed-time AI have greater pregnancy rates to sexed semen.
“Animals not in heat are not good candidates,” emphasized Hall.
Timing of insemination with sexed semen appears to have an affect on pregnancy rates, since sexed semen remains viable for a shorter time after insemination. Hall said inseminating estrus cows at the normal fixed time, but delaying insemination of non-estrus cows until after inducing ovulation with GnRH (gonadotropin-releasing hormone) may offer better results.
“The GnRH would be given to non-estrus cows at the normal insemination time, but insemination would be done 20 hours later,” explained Hall.
Sire selection is another consideration when using sexed semen, as bull fertility differences appear to be magnified after semen is sorted for sex. Hall said increasing sperm dose offers little improvement.
Using sexed semen in superovulated cows to produce embryos also results in decreased reproductive efficiency. According to Hall, researchers noted a 20%-35% reduction in the number of transferable embryos when using sexed semen.
In vitro fertilization (IVF) drastically reduces the number of sorted sperm needed to fertilize an oocyte. Instead of millions of sperm, IVF requires only 600-1,500 sorted sperm to fertilize an oocyte (egg). Hall said this greatly increases the potential number of sexed offspring from a sire.
Pregnancy rates from IVF cultured embryos fertilized with sexed semen range from 30%-50%. While these pregnancy rates may seem low, they are offset by the number of embryos that can be produced.
Currently, the most common beef industry application of sexed semen is to increase the number animals of the desired gender in purebred operations. It may be used to increase the number of sons from a popular sire or to produce more daughters from a maternal line. The latter also might be applied in commercial operations seeking to produce more replacement heifers. Hall explained how the University of Idaho has used this strategy to produce Hereford-Angus-cross females by inseminating selected cows with X-sorted semen.
Hall foresees the day when commercial operators may use sexed semen to shift the gender ratio of calves produced to more steers. For example, small to mid-sized operations that currently must sell mixed loads of calves might be able to market load lots of steers. Hall warned that a sufficient marketing advantage would have to be achieved. Under current conditions, an average premium of $200 per head is probably required. Improvements to sexed semen technology — higher pregnancy rates in particular — are needed to make application in commercial operations economically viable.
Hall spoke during Wednesday’s ARSBC session focused on current topics in reproductive management. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and to view his PowerPoint slides and proceedings paper. This comprehensive coverage of the symposium is compiled by the Angus Journal editorial team. The site is made possible through sponsorship by the Beef Reproduction Task Force.
Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.