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Cows find their ideal voluntary waiting period

Brandt Kreuscher for Progressive Dairyman Published on 01 March 2018

A decade ago, the National Animal Health Monitoring System (NAHMS) Dairy 2007 study showed the average voluntary waiting period (VWP) on U.S. dairy farms was 54.8 days in milk and did not differ by herd size.

In other words, most dairies waited about two months to breed cows for the first time after calving.

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There are several good, scientific reasons for that decision.

Researchers from Penn State University note, after calving, the reproductive tract of the cow typically needs 30 to 40 days to involute (heal and shrink back to a normal size) after a trouble-free calving, and fertility typically will continue to increase until about 100 days in milk as negative energy balance is worked out, postpartum health issues are resolved, and the reproductive system establishes regular cyclicity.

Still, the 60-day VWP industry standard has become less standard in recent years. Advances in technology and actionable data, along with an enhanced understanding of reproduction and improvements in animal health and well-being, are helping pave the way in implementing the most effective VWP for individual dairies – and individual cows.

Variable VWP

For instance, not long ago a significant number of farms reduced their VWP by 10 to 15 days or more in an effort to provide more opportunities for cows to conceive, theoretically improving overall reproductive performance.

In many cases, it made sense because this strategy increases the number of possible services, thereby increasing pregnancy odds and overcoming suboptimal fertility or heat detection.

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The last thing farms using this plan want or need is for too many cows to reach 100 to 120 days in milk or more and not become pregnant.

However, many dairies are now choosing to selectively extend days to intervention for breeding to 70 or more days, especially those that have adopted animal monitoring technology.

The goal is the same: increased reproductive performance. But the path to get there is a little different. With reliable animal monitoring, high-producing cows not cycling prior to 70 or 80 days in milk can be identified. As a result, some producers have become more comfortable waiting longer to breed these individual cows.

Because farms that utilize monitoring technology are able to effectively detect estrus and implement breeding protocols within a narrow time frame, a longer VWP is an economically viable solution that takes individual cow or group needs into account.

Still, some dairies have taken VWP management a step further to individually manage cow reproduction.

Electronic cow monitoring reports now allow dairy managers to easily see the number of heat events since calving, the intensity of the estrus event, the number of health events and milk production.

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These factors allow dairies to also construct a selective, individualized protocol for breeding cows before a longer VWP – for example, on a second system-recorded estrus, acceptable body condition score, no health events and a specific milk production benchmark.

Dairy perspective

A 1,000-cow Midwest dairy found ratcheting down its VWP to improve reproductive success was not the answer to its reproductive challenges.

In fact, animal monitoring data for the herd indicated some cows needed more time after calving to recover, not less.

Further, the dairy fine-tuned its heat detection program using actionable data to effectively schedule optimal insemination time. At the same time, it used timed-A.I. protocols on an as-needed, prescriptive basis to address those cows that needed a little extra help in becoming pregnant.

Given these factors, the dairy formally extended its VWP to 75 days. The farm tracked performance following the change and notes conception rates rose and the dairy now routinely attains a 32 percent pregnancy rate.

This action also enabled the dairy to achieve higher peak milk for a longer period of time to maximize productivity without extending the cows’ calving interval.

The dairy heard what the cows were telling managers. The cows didn’t necessarily need extra time to conceive (with a shorter VWP) because the dairy efficiently managed animal health and reproductive performance. The cows needed the extra time afforded by a longer VWP to boost overall health and productivity.

And the dairy is comfortable breeding individual cows prior to the VWP as long as these animals are healthy and meet the farm’s criteria for milk production, body condition score and estrus – as detected by the system.

Research support

Research presented at the 2016 Joint Annual Meeting of ASAS – ADSA – CSAS – WSASAS bears this out. Results indicate increasing the VWP from 60 to 88 days can have a positive effect for some cows – such as first-lactation cows – and be neutral for others. This means a longer VWP can be beneficial for the entire herd under good dairy management.

The trial was conducted with 1,392 cows and compared breeding cows at 60 days in milk versus 88 days in milk using a protocol for timed A.I. (double Ovsynch). All cows were managed in the same manner with heat detection and timed A.I. after resynchronization of ovulation with Ovsynch.

Results show:

  • An 8.7 percentage point increase in conception rate for first-lactation animals.

  • No statistical difference in conception rate for second-lactation- and-higher animals with the longer VWP.

  • Cows in the longer VWP group had better body condition scores than those in the shorter VWP group.

  • Cows in the shorter VWP group compensated for lower conception rates to first service due to the additional opportunities to become pregnant from multiple services.

Ultimately, the research shows dairies have options when it comes to VWP decisions. The important consideration is to have a sound reason for doing what you do, then monitor results to make any needed modifications as conditions warrant.

Run the numbers

In the end, VWP – like most management parameters – can be customized and tailored to meet specific herd conditions and management abilities as long as you listen to everything your cows tell you.

That means tapping into actionable data available via animal monitoring systems and considering postpartum health, efficiency of heat detection, first-service conception rates and anticipated late-lactation milk production.

In a high-producing herd with an effective timed-A.I. program or closely managed animal monitoring data, a VWP set longer than 60 days can be a successful alternative to the long-held industry rule of thumb – when correctly executed.  end mark

References omitted but are available upon request. Click here to email an editor. 

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