Jerry Gaska, D.V.M.Subclinical ketosis quietly lurks in dairy herds, but its negative impact on feed intake, reproductive efficiency, milk production, immune function and more can't be ignored.

The ketone body most commonly used to diagnose subclinical ketosis is blood ?-hydroxybutyric acid (BHBA). A cut point of 1.2 mmol/L or greater is an indicator of subclinical ketosis.

At the Professional Dairy Producers of Wisconsin (PDPW) Business Conference, Jerry Gaska, D.V.M., the dairy manager at Nehls Brothers Farms, shared testing and treatment protocols from their 2,000-cow dairy in Juneau, Wis.

In their herd, they alternate ketosis testing between cows and heifers. One week they will sample about 20 fresh cows three to 14 days in milk; the next week, about 20 fresh heifers.

If 15 percent or less of animals fall under that 1.2 mmol/L mark, the regular testing protocol continues. If more than 15 but less than 40 percent are positive, they will sample all cows three to nine days in milk and treat those with high BHBA levels. If 40 percent or more of cows register high, all fresh cows will be treated. Their treatment is 300 cc of propylene glycol, given orally once daily for five days.

Gaska uses spreadsheets and DairyComp 305 records to track the farm's test results over time, and he unveiled some interesting trends within their herd. One was the correlation between dry period length and BHBA level. On their farms, 10 percent of cows with a dry period of 60 days or less had an incidence of BHBA 1.2 mmol/L or higher. Cows with a longer dry period, over 60 days, had an incidence of 24 percent, despite the preventative treatment for ketosis those cows already received.

Another trend was days in milk during the previous lactation. Cows with less than 320 days in their last lactation were positive 9 percent of the time; of those with lactations over 320 days, 17 percent had elevated BHBA.

Age at first calving made a difference, too. Among heifers that calved at 24 months of age or less, 12 percent were high. For heifers over 24 months, almost twice as many, 21 percent, had elevated BHBA.

Are certain tendencies taking place in your herd? Gaska encouraged producers to track BHBA levels and watch for trends. "With ongoing monitoring, you can detect changing trends in subclinical ketosis levels and institute intervention," he said. "In doing so, testing and treatment programs can be targeted to high-risk cattle."

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(c) Hoard's Dairyman Intel 2015
March 23, 2015
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