Can Sexed Semen Work in Your Herd?
Beef specialist considers limitations, opportunities and challenges of using gender-selected semen.
SIOUX FALLS, S.D. (Dec. 4, 2012) — Sexed semen from beef sires has been commercially available for a few years, but is its use really practical for artificial insemination (AI) implemented at the ranch level? According to University of Idaho Extension Beef Specialist John Hall, sexed semen may be a reproductive technology that's time has come. Hall talked about limitations, opportunities and challenges associated with gender-selected semen during the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium Dec. 3-4 in Sioux Falls, S.D.
Hall admitted that data from controlled studies is limited, and neither is there sexed semen available from a large number of beef sires. Still, said Hall, the number of beef bulls with gender-sorted semen available increased from zero to 70 between 2008 and 2011.
“While not an overwhelming selection of bulls and genetics,” said Hall, “there are now sufficient numbers of beef bulls with sexed semen to begin to meet the needs of the seedstock sector and address the wanted traits for the commercial producer.”
Hall said technical services personnel from the major AI studs report a 10%-15% reduction in pregnancy rates to sexed semen compared to conventional semen. That is comparable with results of studies where sexed semen was used in dairy heifers, as well as results of more limited research involving beef heifers. Results from work involving dairy cows suggested pregnancy rates from sexed semen would be even more reduced when used in older females.
“Use in cows wasn’t recommended,” said Hall. “We did (at the University of Idaho), with the goal of making replacement heifers. Results were encouraging. Even the lowest pregnancy rates were close to 50 when using sexed semen with fixed-time AI.”
Generally, said Hall, little difference has been seen between pregnancy rates of beef cows and heifers. For both there was similar depression of pregnancy rate. However, lower pregnancy rate and greater variation may be seen in heifers, when fixed-time AI systems are used.
Hall said he believes results in beef heifers and cows indicate that application of sexed semen to the beef industry is feasible. Admittedly, there is considerable variation in pregnancy rate. There may be several influential factors, but Hall noted significant variation in pregnancy rate may be attributed to choice of sire. Differences in bull fertility may be magnified after semen has undergone the sperm sorting process. Increasing insemination dose from 2 million to as much as 10 million sperm does not result in much improvement of results.
“This suggests the lower fertility is probably due to uncompensable semen traits,” said Hall.
In summary, Hall said expectations from AI with sexed semen will likely result in 10%-20% lower pregnancy rates in cows and heifers, with increased variability. When used with embryo transfer (ET), a 25%-35% and maybe 50% reduction in transferable embryos might be expected. Hall said application of sexed semen with ET still holds promise for seedstock producers seeking bull calves, because few recipient cows will be tied up with female embryos.
Another application for sexed semen is for development of maternal lines of females by targeting replacement heifer production. Hall said an example might be to maintain a Hereford-Angus cow base, which could be bred to terminal sires.
“A producer wouldn’t have to breed as many cows to maternal bulls to get replacement heifers,” added Hall. “If gene markers are developed to help identify the most ‘ideal’ heifers, those would be good candidates for insemination with sexed semen.”
Hall spoke during Tuesday's ARSBC session focused on advancing technologies. Visit the Newsroom at www.appliedreprostrategies.com to listen to Hall's presentation and to view the accompanying PowerPoint and proceedings paper.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and LiveAuctions.tv.