In previous Dairy Performance articles, we’ve discussed the importance of testing for and monitoring subclinical ketosis in dairy cows. We’ve often highlighted the Precision Xtra® blood meter as a simple cowside tool for evaluating ketosis. But is it really that simple? We conducted an on-farm survey last year to ask that very question.
What are we measuring?
Before we discuss effective ways to detect ketosis, let’s first review how ketosis develops. At freshening, a cow’s dry matter intake is already at a low point. Her increased energy demand for lactation outpaces her low intake, pushing her into a negative energy balance (she’s burning more than she’s consuming). Thus, her body begins to burn fat to meet her energy needs. The problem arises when her body mobilizes more fat than her liver can metabolize completely, leading the development of ketones, which will circulate in her bloodstream. Her body can’t burn the ketones for energy and she thus remains in a negative energy balance.
Measuring the ketones in a cow’s bloodstream shows the severity of ketosis. One of these ketones is beta-hydroxybutyric acid (BHBA). Using a very small blood sample, the Precision Xtra meter measures the level of BHBA in the cow’s blood. This kind of tool is necessary because, unlike clinical ketosis, subclinical ketosis cannot be diagnosed by outward symptoms.
We conducted our subclinical ketosis survey during a 10-month time period between March and December 2012. The survey took place on 18 dairy farms located in Iowa, Minnesota and South Dakota. These farms ranged in size from 500 to 4,500 cows. Most farms milked primarily Holsteins, but one farm had an all-Jersey herd and one was mostly crossbred. For safety and tracking purposes, farms enrolled in our survey needed to have headlocks in the fresh pen and either DairyComp 305 or PC Dart records.
In total, we tested 1,164 cows with the Precision Xtra meter. All of these cows ranged from two to 15 days in milk. We tested cows in groups of 12 or 24 and took three sample sets of cows on each farm roughly two weeks apart. This ensured we would never test the same cow twice.
What we learned about the meter
As we conducted the survey, we found that the Precision Xtra meter was indeed easy to use. The handheld meter requires only a very small droplet of blood placed on the test strip. This sample is easily attained from the tail vein. Once blood is applied to the strip, the meter displays a result in 10 seconds. We found we could test groups of cows in a very minimal amount of time.