Insemination Factors Affecting
Fertilization in Synchronized Females
STILLWATER, Okla. (Oct. 8, 2014) — Planning and implementing an estrus synchronization program prior to artificial insemination (AI) represents an investment of time and money by cow-calf producers. The last thing a producer wants is having that investment compromised by problems related to the actual insemination process.
University of Idaho Reproductive Physiologist Joe Dalton explained the difference between compensable traits and uncompensable traits when evaluating semen quality.
University of Idaho reproductive physiologist Joe Dalton talked about insemination factors that affect fertilization during the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium hosted Oct. 8-9 in Stillwater, Okla. He discussed potential problems stemming from semen quality, handling of semen, insemination technique and timing of insemination.
According to Dalton, differences in semen quality traits exist among bulls, including sires collected for AI. Reduced fertility in some bulls is due to compensable semen traits affecting the viability or morphology of sperm cells and making them unable to compete for fertilization of the ovum (egg). Dalton said compensable traits can be overcome or minimized by increasing the number of sperm delivered during insemination. Reputable AI organizations routinely adjust the AI dose when compensable deficiencies are known.
Dalton said low fertility also may be the result of uncompensable traits, usually related to damaged DNA. In this case, a bull’s semen contains unacceptable levels of abnormal sperm, which can compete and are capable of starting the fertilization process, but are unable to complete it.
“The result is reduced fertility regardless of sperm dosage,” explained Dalton. “We can double and even triple the dose and it will not improve the fertility of these bulls.”
Dalton said such bulls should not be collected and used for AI. To reduce risk, he recommended sourcing semen from only reputable AI studs.
Timing of insemination also affects fertilization success. Dalton explained that, following insemination, six to 12 hours are required for sperm transport to the fertilization site, and to gain the capacity to fertilize the ovum. However, an ovum that waits too long and becomes "aged" may ultimately yield a low-quality embryo. Insemination should occur near enough to the time of ovulation to maximize sperm access to the ovum, but not so late that an aging ovum waits in the oviduct.
“If anything, we want to err on the side of the sperm and have it waiting on an egg,” added Dalton. “We don’t want the egg waiting on the sperm to arrive.”
Operator error is another factor that often affects fertilization. Dalton said technicians or producers faced with the challenge of inseminating numerous females in a short period of time should resist the temptation to thaw too many semen straws simultaneously.
“Thaw no more than you can use in 10 to 15 minutes. After that much time, semen quality goes off the cliff,” warned Dalton, adding that proper semen handling and correct deposition of semen also are critical to successful fertilization. “We (all inseminators) should be retraining ourselves just like the major AI companies retrain their personnel.”
Dalton concluded by advising producers using natural-service sires to make sure all bulls have undergone a complete breeding soundness examination, not just a semen test.
Dalton spoke during Wednesday’s ARSBC session focused on strategies for AI success. For more information, visit the Newsroom at www.appliedreprostrategies.com to view his PowerPoint, read the proceedings or listen to the presentation.
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 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.