A Review of AI Protocols
A Review of AI Protocols, Synchronization and Best Practices
Of all the innovations that have helped shape the landscape of dairy farming into what it is today, artificial insemination (AI) is arguably among the single most influential vehicles to accelerate genetic progress.
As one of the earliest animal industries to embrace this breeding mechanism, dairy farmers have gotten this down to a smooth, seamless practice with very high rates of success and cost effectiveness. Beyond the convenience and cost savings compared to traditional live cover, AI has allowed for faster genetic improvement for individual farms and the national herds. It’s also improved reproductive efficiency and improved biosecurity.
And while breeding protocols are pretty standardized across dairies, so much that it’s typically just another daily activity, it still involves attention to detail and intentionality. This means having your breeders trained and reliable with proven systems in place for heat detection, synchronization, animal handling and recordkeeping.
Standard and Best Practice Protocols
Even with the most finely tuned synchronization protocols in place, everyone on your repro team ought to know the basics of natural heat cycles and detection. This includes knowing how to observe the basic signs of estrus, how the estrous cycle works and the best time to inseminate upon initial signs (AM-PM rule of breeding 12 hours after).
As a review, key signs of heat include mounting activity, clear mucus discharge, restlessness, decreased feed intake, vocalization and swollen vulva. Keeping accurate heat detection and breeding records helps identify silent heats, repeat breeders and cows that may need further reproductive evaluation
Understanding the natural cycle also helps ensure that synchronization programs are in use effectively. Even when relying on timed AI, a good eye for heat detection and familiarity with cow behavior can make all the difference between a conception and a missed opportunity.
Synchronization Protocols
There’s no shortage of synchronization programs for use with timed artificial insemination and live cover. Using these protocols reduces the burden of observing heats and waiting for animals to be flagged, even when excellent herd-management software and data tracking are in place. It can also help improve conception rates in some cases.
One of the most widely used synchronization methods is the traditional Ovsynch protocol, which involves administering GnRH on day zero, PGF₂α seven days later, a second GnRH dose on day nine, and performing timed insemination on day ten. This approach helps induce ovulation in a predictable window, for timed breeding without waiting for visible signs of heat.
Another option is a CIDR-based protocol, which uses a Controlled Internal Drug Release device to maintain progesterone levels during the cycle. While studies show that CIDRs can indeed improve conception rates, their widespread adoption in dairy. Limits mainly by cost, convenience and management practicality.
Injection synchronization programs like Ovsynch are easier to implement, require no intravaginal handling, and tend to fit better with the management routines of most dairy herds.
However, they can be useful in certain cases where a progesterone “boost” might be needed. This included anestrous or subfertile cows not returning to their cycles postpartum, embryo transfer recipients and resynchronization after multiple failed AI attempts.
Some herds also benefit from Pre-Synch programs, where cows receive PGF₂α injections before beginning Ovsynch. This keeps more cows actively cycling when they enter the synchronization program, improving the overall success rate. Fixed-time AI eliminates the need for individual heat detection, making it a strong option for larger operations where managing many animals at once can be a logistical challenge.
Whatever the chosen protocol, don’t be shy about looping in your veterinarian or repro tech in your program, especially for animals that are having trouble.
Proper Semen Handling
Even the best synchronization plan can fail without correct semen handling. The quality of the semen from storage to insemination directly impacts conception rates, and mishandling can compromise fertility in subtle but significant ways.
Frozen semen should always be below the frost line in a liquid nitrogen tank to maintain viability. When it’s time to breed, thawing must be complete carefully according to supplier guidelines which is typically around 95°F for 30 to 45 seconds.
Once thawed, the straw should be loaded promptly into a clean, dry AI gun and used within about 15 minutes. Any delay or exposure to temperature changes can cause sperm damage that reduces fertility.
Cleanliness is a given. Equipment should be free of water, dirt or disinfectants, as even small contaminants can harm sperm cells. Before breeding, double check the straw identification to make sure to use the correct sire.
Attention to these small details can all make a measurable difference in conception outcomes. Reproductive efficiency relies not only on good protocols but also on disciplined handling practices and communication across the entire breeding team.
Modern Adaptations
Advances in reproductive technology have given producers more tools to improve herd genetics, reproductive efficiency, and overall productivity. One of the most notable developments is sexed semen. This technology is particularly useful in herds where replacement heifers are a priority, or where the economic value of one sex is higher than the other. While conception rates with sexed semen may be slightly lower than conventional semen, careful handling and proper timing can help maintain high success rates.
Automated estrus detection systems are another modern adaptation helping teams manage reproduction more efficiently. These systems use activity monitors, pedometers or even tail-mounted sensors to detect subtle changes in behavior that indicate heat. By alerting staff to cows in estrus in real time, these systems reduce the reliance on visual observation alone and can improve the timing of insemination, ultimately boosting conception rates and labor efficiency.
Understanding natural estrous cycles, maintaining proper semen handling, and implementing synchronization protocols lay the foundation for high fertility rates. On top of that, modern tools such as sexed semen, genomic selection, and automated estrus detection systems allow producers to push efficiency, accuracy and genetic progress even further.
At the end of the day, the most successful programs are those where attention to detail, consistent protocols, and well trained personnel intersect with innovative technology.
By Jaclyn Krymowski for American Cattlemen
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