Profitable Uses of Sex-Sorted Semen
JOPLIN, Mo. (Sept. 1, 2011) — In recent years, it has been possible for cattle producers to predetermine the gender of calves, with greater than 90% accuracy, when artificially inseminating (AIing) heifers or cows with sex-sorted semen. In a presentation delivered to the Applied Reproductive Strategies in Beef Cattle (ARSBC) conference in Joplin Aug. 31-Sept. 1, Colorado State University (CSU) animal science researcher George Seidel talked about the flow cytometry technology that allows sorting of sperm cells by gender. He offered procedural tips for AI using sexed semen and noted the potential applications for both seedstock and commercial cow-calf operations.
Seidel said the limitations of sex-sorted semen include the higher cost, compared to AI with typical non-sorted semen. Sexed semen usually costs $15-$25 more per dose. The technology is expensive, and commercially available sexed semen has lower numbers of sperm per dose (about 2 million) compared to conventional semen (more than 10 million sperm per dose). Partly due to the lower sperm count per dose, but also because the sorting process subjects sperm cells to stress, pregnancy rates following recommended synchronized AI are lower than rates usually achieved with unsexed semen.
“Typically, pregnancy rates are 10 to 12 percentage points lower with sexed semen,” Seidel explained. “By far the biggest cost is lower fertility.”
According to Seidel, sexed semen is more fragile than conventional semen and requires careful handling and excellent management of synchronized AI if producers are to realize maximum benefit. Seidel said the optimum timing for AI with sexed semen appears to be 18 hours following the onset of estrus. Protocols incorporating heat detection are preferred.
“This is not a product for fixed-time AI,” Seidel stated. “But if you must, the best time appears to be six hours later than for unsexed semen. You want the eggs waiting for the sperm in this case — not the other way around.”
Potential applications for sexed semen include breeding cows to produce male calves. Weaned steers generally are more valuable than heifer calves, but Seidel warns that the additional value may not be sufficient to compensate for the lower fertility (and higher cost) of sexed semen. Choosing to produce more male calves is generally going to be more profitable for seedstock producers wishing to produce more bulls from a given number of cows.
“One of my favorite applications of sexed semen is to breed heifers to have heifer calves,” stated Seidel, noting that first-calf heifers are less likely to experience dystocia when delivering generally smaller heifer calves. “Using sexed semen can increase the percentage of heifer calves and the number of potential replacement females, either to expand the herd more rapidly or to produce bred heifers for sale.”
Despite its current limitations, Seidel said sexed semen is likely to be beneficial to the long-term health of the beef industry, largely because of its potential for enhancing production and hastening the achievement of production goals.
Seidel spoke during Thursday's ARSBC session focused on current topics in reproductive management. Visit the Newsroom at www.appliedreprostrategies.com to view the PowerPoint slides and proceedings paper submitted by Seidel to accompany his presentation. Audio of the presentation will be available soon.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by Angus Productions Inc. (API), the site is made possible through sponsorship by the Beef Reproductive Task Force, SEK Genetics, and liveauctions.tv. Coverage includes summaries of the speaker presentations, PowerPoints, proceedings and audio.
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