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Report uses milk tests to predict levels of ketosis in the herd

Kelli Boylen Published on 06 August 2015

Mike Larson

Mike Larson, general manager of Larson Acres, says they were surprised to learn just how many of the cows in their herd had subclinical ketosis. Since there were no symptoms, the condition went undetected and untreated.



KetoMonitor, an Ag Source Cooperative Services product, was introduced last winter. The Larsons have been using it longer than most producers since they were one of the test farms where researchers collected information to create the product.

Six Larson families milk 2,400 cows three times daily on their farm near Evansville, Wisconsin. Their family has farmed at that location for 90 years, and they operate about 5,000 acres.

The report estimates herd ketosis prevalence on the day of milk test to help guide management and nutrition decisions. It alerts dairy producers when prevalence levels increase above desired targets, at which time blood-based testing protocols should be implemented to more closely manage ketosis in fresh cows. The report can be used to track the impact of management changes on transitional cow health.

Larson says it has helped them to not only understand the frequency of subclinical ketosis in their herd but also the patterns behind the subclinical cases. This allows them to focus on those challenge areas, he says.

They discovered most of their subclinical cases of ketosis were in second-lactation cows at 11 to 20 days in milk. Many of the cows were overconditioned, had extended dry periods and, in some cases, had experienced lameness.


Cows experiencing subclinical ketosis at Larson Acres are considered to be positive ketosis cases, and treatment protocol differs depending upon the severity of the case. They are also adjusting their post-fresh ration to see if they can reduce the number of cases.

Heather White, Ph.D., assistant professor of nutritional physiology, Department of Dairy Science at the University of Wisconsin – Madison, leads the team that developed KetoMonitor. She says the average cost of ketosis (both clinical and subclinical) is about $289 per case.

A herd with 1,000 calvings and 30 percent incidence each year will lose $90,000 annually. If they can reduce the incidence from 30 percent to 15 percent, they can recover $50,000 of that potential loss.

“We have been continually analyzing the growing database generated by [the report’s] sampling and have learned several things,” she says. “First, herd prevalence is at 19 percent across the tested herds, with prevalence in heifers at 7 percent and second- and greater-lactation animals at 27 percent out of more than 90,000 fresh cow samples.”

Subclinical ketosis affects 40-60 percent of cows (total number of new cases found in repeat sampling of the same cows during the fresh period).

The report samples each cow once a month, so it provides the “prevalence” of ketosis (or in other words, a “snapshot” of the number of cases) in all fresh cows on test day.


White explains that when the prevalence of subclinical ketosis is 27 percent of cows entering their second or later lactation, it means about 67 percent of multiparous fresh cows actually have subclinical ketosis at some point during the transition period.

Within the dataset, White says, the 30-day culling rate is more than three times greater for a predicted ketosis-positive cow compared to a healthy cow (4.5 percent versus 1.4 percent). Also, peak milk production is 4 pounds less per day for first-lactation cows and 3 pounds less per day for second- and greater-lactation cows that were predicted positive at their first milk test.

dairy barn

Research shows they are more likely to develop a displaced abomasum and are less likely to conceive at first service. “These negative outcomes associated with ketosis highlight the benefit of managing ketosis to reduce prevalence,” she says.

White says the report has been very accurate at determining herd prevalence across farms they have worked with over the last six months, usually predicting the ketosis prevalence within 2 percent compared with blood testing.

“This provides very valuable information to the farm on prevalence and allows them to monitor ketosis prevalence in response to change,” she says. “Several farms working with me or a member of the team have had a higher-than-desired prevalence and have been able to reduce their ketosis prevalence through improving nutrition or management.

Some farms are using the data on predicted positive cows to identify patterns that help them strategize closer monitoring. For example, if most of a farm’s predicted positive cows have longer dry periods, any cow that calves in after a longer-than-average dry period would be blood-tested for ketosis.”

David Rhoda, DVM, works with the Larson family on herd health. “It’s too early for us to be definite about how we’ll use this, but I am excited about what I’ve seen so far. We’re anxious to continue the field studies, and we feel working on this at the subclinical level is a very positive plan,” he says.

“It is my personal opinion that this work will teach us more about management risk factors from the previous lactation and dry period, just as transition dry period management did in the last 10 years,” Rhoda adds. “I’m always interested in new tools for old problems that have been especially difficult, and ketosis certainly fills the bill.”

Although it was not designed to be an individual cow test, Larson says he is excited about the impact the data on individual cows will have on their operation.

“Mike and his team are certainly using the [report’s] outputs strategically, and he has been instrumental in our research trying to develop an individual cow identification tool that can be used practically and economically on-farm,” White says.

She says their current research, both on farms such as the Larsons and at the UW – Madison research facility, is focusing on repeat sampling cows twice a week during the fresh period so they can identify definite diagnosis as healthy or ketotic.

They are using this data in their research to identify cows genetically predisposed to ketosis so they can be identified prior to calving and monitored more closely.

This repeat sampling may also strengthen the report and expand it to an individual cow identification tool in the future. This would be most practical on larger farms that could incorporate weekly milk sampling into their SOP, and the goal is to be able to use that weekly milk test to identify cows that need treatment without needing a follow-up blood test. PD

Kelli Boylen is a freelance writer in Waterville, Iowa.

PHOTO 1: Mike Larson says a new ketosis report has helped his dairy team understand both the frequency of subclinical ketosis in their herd and the patterns behind the subclinical cases.

PHOTO 2: Current research through the KetoMonitor team is repeat sampling cows twice a week during the fresh period so that they can identify definite diagnosis as healthy or ketotic. Photos courtesy of Kelli Boylen.