This article was #20 of the Top 25 most well-read articles on in 2012. to jump to the article. It was published in the January 1, 2012 issue. Click here for the full list of the Top 25. With most producers keeping an eye on the latest technologies available, the use of automated heat detection systems has also garnered significant attention during the past few years.

Lee john
U.S. Dairy Technical Services Veterinarian / Zoetis
Lee received his DVM from Oregon State University and is based in California.

In this article, Pfizer Animal Health’s John Lee highlights points that producers should consider before investing in these systems, especially if they already have a successful breeding program.

Q. Under what circumstances would automated heat detection systems be beneficial on farms that currently follow a synchronization program?

Automated activity monitor systems (AAMSs) may benefit operations with low insemination risk or that can’t enroll cows weekly in a properly managed synchronization program.

Every dairy aims for a high calving rate. Pregnancy rate is the best early indicator of future calving rate.


Key drivers of pregnancy rate are:

  • Percent eligible animals inseminated every 21 days (insemination risk)
  • Percent inseminated animals which conceive (conception risk)

If more cows get inseminated, more cows will likely get pregnant. Heat detection aids, such as AAMSs, may help catch more animals in heat, which should increase insemination risk. Herds with high insemination risk and pregnancy rates are unlikely to benefit.

Automated activity monitor systems may also benefit operations with people who are motivated to make the system a success. Keep in mind AAMSs are a heat detection aid. They do not directly diagnose heats. Flagged cows’ activity warrants further investigation to determine if they are in fact in heat. It’s a must to have properly trained personnel.

Also AAMSs require active management. Someone with the interest and time must manage the system and interpret data. Will personnel unable to properly manage a synchronization program properly manage an AAMS? —John Lee, Managing Veterinarian, Pfizer Animal Health


Over the years, science has delivered reproduction management technologies that have helped dairy producers become more efficient and productive. Timed artificial insemination (TAI) is one practice that greatly improves reproductive performance on dairies.

Recently, automated heat detection systems are showing promising benefits in some herds as well. You might even be wondering if this new technology can improve your dairy’s breeding performance.

Much like other reproductive programs, the usefulness of automated heat detection depends on the individual dairy’s management system, heat detection capabilities and breeding goals.

Get cows serviced

A successful reproductive program depends on inseminating cows for the first time as soon as possible after the end of the herd’s voluntary waiting period.

Every cow has what’s known as an “allowable breeding space.” This is the length of time in which it is economically viable to continue trying to get that individual cow pregnant.

The number of days to first service is the biggest driver of how many potential breeding opportunities a cow will have within the allowable breeding space.

Synchronization programs, including pre-synchronization for first service, benefit all herds – including those with automated heat detection systems – by ensuring all cows are inseminated shortly after the end of the voluntary waiting period, with a high likelihood of a successful outcome.

Pharmaceuticals used in synchronization programs address many ovarian and uterine health problems. This includes cows which are anovular, anestrous, have a pyometra or are not actively expressing heat.

Once cows are bred for the first time, the next-most important aspect of successful reproductive management is to quickly identify open females and re-breed them. Accurate heat detection will decrease the interval to next insemination for these cows.

However, a percentage of open cows will not be identified by heat detection. These are the cows found open at pregnancy check.

Enrolling these cows in synchronization programs helps ensure these open cows are reinseminated in a timely manner and reduces the interval between breedings for those failing to conceive but not expressing heats well.

Using a resynchronization program, producers can guarantee all cows will be reinseminated within 11 days of an open vet check diagnosis. This is powerful because cows diagnosed open have already been missed in heat once, otherwise they would not have been up for pregnancy check.

Cows must show heat

Producers considering automated heat detection should be aware that this tool will only identify cows with normal heat activity. Every dairy has a population of cows that do not show heat for a number of reasons.

Some have uterine health problems or will not cycle properly due to ovarian problems. These cows also can be in silent heat or have an illness or lameness that prevents them from showing heat. Even healthy cows can vary in the duration and intensity of estrus.

It is not unusual for more than 20 percent of the cows in a herd to not express heat well enough for detection by any method, including an activity-based monitoring system. Synchronization programs help ensure cows not detected in heat by any method are inseminated in a timely manner.

Consider carefully

If you are considering adopting an automated heat detection system, be prepared to make changes in your herd’s breeding routines as well as a significant upfront capital investment in equipment.

Automated heat detection systems are designed to identify cows displaying active estrus expression. If your herd is struggling with low heat detection rates, investing in an automated heat detection system may help improve heat detection intensity and identify more cows for insemination.

But operations with already high heat detection rates may not see a favorable return on the investment.

Successful timed-A.I. programs effectively eliminate the variability in estrus detection and make efficient use of the allowable breeding space. Automated heat detection may work in tandem with synchronization to improve insemination efficiency and help make better use of the allowable breeding space for some dairies.

However, dairies with high pregnancy rates should carefully consider a decision to change any aspect of their breeding program. If your current breeding program achieves a pregnancy rate in the 20s or higher, meddling with your system could result in no change or, worse, a decrease in performance rather than the improvement you expect.

Before making any changes, it is important you take time to review your breeding program with your veterinarian. No system is “one size fits all,” and your veterinarian can provide key insights before you make a large investment or changes.

Make sure that whatever program you are implementing on your dairy provides your cows their best chance of timely pregnancy. PD

Things to consider ...

Automated heat detection technology can be a tool to improve reproductive performance. But it isn’t for everyone. If you’re considering the investment, make sure to conduct a comprehensive evaluation that includes the cost of equipment and time it will take to break even.

That time to break even should include a “sensitivity analysis,” which looks at different outcomes – optimum results, median range results and “worse case” (minimal repro improvements) after a significant investment.

Here are a few other questions to ask yourself:

  1. What is the current herd pregnancy rate with my current program?
  2. What is the current heat detection rate with my current program?
  3. What do I think will improve with an automated heat detection system?
  4. Will the automated heat detection enhance my current system?
  5. What are the risks with implementing this with my current system or using this to replace my current system?
  6. Is the cost worth it?
John Lee