Subclinical ketosis is a common fresh-cow challenge that affects even the best-managed herds. Zeroing in on excellent care of transition cows is critical to optimal herd health, reproduction and production levels.

Dairy producers know the impacts of subclinical ketosis.

  • decreased milk production and increased cull rates in the first 30 days
  • worse first-service conception rates
  • more incidence of displaced abomasum

When considering cows with both subclinical and clinical ketosis, the economic burden amounts to about $289 per case.

Research done at the University of Wisconsin-Madison in the laboratory of Heather White led to the development of KetoMonitor. It’s a tool that uses milk-test and cow-management data to assess if a cow has subclinical ketosis. In partnership with AgSource Cooperative Services, KetoMonitor is helping researchers better understand how on-farm practices may be tweaked to curb the effects of the costly disease.

Among other points of data, length of dry period and its impact on subclinical ketosis was recently studied. Farm records collected by AgSource show the average dry period for cows with subclinical ketosis is 66 days. That compares to 55 days for cows that don’t develop subclinical ketosis. That doesn’t mean a longer dry period will cause subclinical ketosis. But it does indicate those cows may be at greater risk and they’ll need extra attention after calving.

First-lactation cows that develop sublinical ketosis have a worse somatic-cell count at first test compared to non-subclinical-ketosis cows. Research shows an average log score of 3.75 in sub-clinically ketotic compared to 2.8 in non-sub-clinically-ketotic primarous cows. Interestingly the difference in first-test somatic-cell count between the two groups is much smaller in mature cows.

Peak milk is better in cows without subclinical ketosis, averaging 81 pounds compared to 75 pounds in cows with subclinical ketosis. The same pattern can be observed in second and later lactations – cows without subclinical ketosis averaged 109 pounds compared to 106 pounds in cows with subclinical ketosis.

Those observations show that cows developing subclinical ketosis in their first lactation produce less milk and have compromised udder health early in lactation. One extra pound of peak milk is estimated to increase 305-day milk yield by more than 200 pounds. The potential milk-production losses of primiparous cows with subclinical ketosis is 1,200 pounds. For multiparous cows with subclinical ketosis the potential loss is 600 pounds. At $14 per hundredweight, that equals $168 and $84 for the lactation.

Cows with longer dry periods were more likely to develop subclinical ketosis. Those subclinical-ketosis cows had lesser peak milk and a better somatic-cell count at first test. The research doesn’t demonstrate that subclinical ketosis causes each of those negative outcomes. But knowing the symptoms may help producers determine which cows are affected so they can intervene sooner.

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Henry Holdorf is a doctoral fellowship student with Purina Animal Nutrition, working in Heather White’s laboratory in the Department of Dairy Science at the University of Wisconsin-Madison. Email hholdorf@wisc.edu to reach him.