Factors Affecting Fertilization
in Synchronization Programs
FORT COLLINS, COLO. (Dec. 3, 2008) — Whether or not cattlemen are using synchronization protocols in beef cattle breeding programs, “the rules of biology” still have to be followed in order to achieve fertilization, Richard Saacke, Virginia Tech professor emeritus, told attendees at the 2008 Robert E. Taylor Memorial Symposium: Applied Reproductive Strategies in Beef Cattle in Fort Collins, Colo.
Richard Saacke, Virginia Tech professor emeritus, recommended insemination six to 10 hours prior to the onset of ovulation to optimize fertilization and embryo survivability.
Saacke emphasized that the bottom line in successful insemination and fertilization comes down to sperm transport in the cow. He explained that insemination places billions of sperm in the cervix that then must travel up the reproductive tract to the oviductal sperm reservoir.
During this process, timing is critical. Numerous sperm get lost in the reproductive tract, and only thousands actually reach the reservoir where fertilization occurs. Quality of the semen is also important during this process because many of the sperm simply do not survive.
“So, in a sense, the female has a selection that she exerts on the sperm,” Saacke said.
To enhance sperm transport in the cow to achieve fertilization, Saacke said three important factors must be considered:
- Bull effect – Saacke emphasized that reliable semen should always be used. He encouraged producers to consider a sire’s reproductive history and make certain natural and AI sires have passed a breeding soundness exam.
- Inseminator – A skilled inseminator can also help reduce AI mistakes commonly made. Saacke said not only does semen need to be handled carefully during the thawing process, but inseminators must also make certain they are skilled in placing the semen in the uterine body. He recommended inseminators take the time to be retrained to ensure they remain proficient at AI breeding.
- Timing of insemination – Most importantly, timing is everything with insemination. Saacke told attendees that, especially when using a synchronization protocol, the time and tightness of ovulation must be known. He explained that accessory sperm must be able to make it up the female’s reproductive tract and into the oviductal sperm reservoir with enough time to access the freshly ovulated egg, but not so late as to ignore sperm transport time in the cow and risk the possibility of missing ovulation.
Saacke shared research that showed if you breed too early, fertilization rates tend to be low, but embryo quality is high. Conversely, if you breed too late, fertilization rates may be high, but embryo quality tends to be lower due to the aging eggs.
Thus, Saacke said, “Timing of AI is a compromise. … We need to go in between and find a happy medium. That’s why we recommend insemination six to 10 hours prior to the onset of ovulation.”
To listen to Saacke’s presentation, view the accompanying PowerPoint or view other presentations from the symposium, visit the newsroom at www.appliedreprostrategies.com.
The Robert E. Taylor Memorial Symposium is conducted by Colorado State University every other year to provide current, research-based information for improving profitability in the beef cattle industry. The ARSBC program was developed by the Beef Cattle Reproduction Task Force to improve understanding and application of reproductive technologies, including AI, estrus synchronization and factors affecting male fertility. In 2008, CSU and the Task Force collaborated to provide the Dec. 2-3 symposium in Fort Collins.
— by Tosha Powell & Kindra Gordon
Click here for accompanying PowerPoint as a pdf file (2.8 MB).
Click here to listen to the audio (8 MB mp3).
Editor’s Note: This article is available as a news release to redistribute per an agreement between the symposium hosts and Angus Productions Inc. Click here to submit a request for a high-resolution photo of the speaker. For additional information visit the newsroom of www.appliedreprostrategies.com.
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