Pay Attention to AI Fundamentals
JOPLIN, Mo. (Sept. 1, 2011) — When you understand even basic reproductive physiology, you appreciate the miraculous nature of something seeming as simple as conception.
Richard Saacke, professor emeritus in the dairy science department at Virginia Tech explained to participants at the Applied Reproductive Strategies in Beef Cattle (ARSBC) conference in Joplin, Mo., that bulls deposit billions of sperm cells in the vagina of a cow during a single mating. Millions of those cells make it to the uterus, thousands make it to the oviduct reservoir and only a few into the oviduct when one is responsible for fertilizing the egg. It takes 6-12 hours for sperm to make it from the point of deposit to the oviduct reservoir.
That’s everything goes right.
Not withstanding the necessity of healthy cattle and accurate application of heat detection or synchronization protocols, Saacke pointed out how important the technician and semen quality are to successful artificial insemination (AI).
Consider the technician. Previous research (see Table 1), underscores the differences between technicians for the accuracy of semen deposition. In one study the semen deposition accuracy of AI technicians with the highest conception rates was 52% higher than that of technicians with the lowest conception rates. Accuracy was defined by the ability to deposit semen in the uterine body.
|Table 1: Site of dye deposition in cows in vivo|
|Conception rate of technicians|
|Site of dye deposition||<70% NR*||>78% *NR|
|• Body of uterus||34%||86%|
|• Right horn||31%||14%|
|• Left horn||4%||0|
|• Anterior cervix||9%||0|
|• Posterior cervix||16%||0|
|*Non-return rate, and indirect measure of fertility|
“The inseminator has much to his or her control,” Saacke said. The rate of thawing frozen semen straws, how carefully semen is handled inside and outside of the tank, it all affects the viability of the sperm.
As for semen quality itself, Saacke stressed the importance of using semen from AI sires collected and distributed by reputable AI firms that place a high priority on examining semen morphology. He explained that identifying abnormal sperm is still the most effective means of identifying sires more or less likely to produce semen capable of producing conception.
Incidentally, Saacke explained science is getting closer to understanding which few sperm — termed accessory sperm — make it into the oviduct for an opportunity to fertilize the egg and why.
Finally, Saacke emphasized the importance of timing.
“It appears optimum reproductive efficiency rate (pregnancy rate) is a compromise using our current techniques and recommendations in AI,” he explained. “If we inseminate too early, we suffer from lower fertilization rates (but embryo quality is good), and if we breed too late, we suffer from lower embryo quality (but our fertilization rate is good). Thus, the intermediate time of 12 hours post-heat would prove optimal when using a precise method for determining the onset of heat.”
For AI with the use of synchronization, Saacke says producers should closely follow the protocol.
Saacke spoke during Thursday's ARSBC session focused on reproductive considerations related to the male. Visit the Newsroom at www.appliedreprostrategies.com to view the PowerPoint slides and proceedings paper submitted by Saacke 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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