Just because a fresh cow tests over the standard threshold typically used to screen for ketosis doesn’t necessarily mean she’s sick. She might be just fine and even rocking and rolling into lactation, according to two University of Minnesota researchers who have studied ketosis extensively.
On a recent episode of The Dairy Signal from the Professional Dairy Producers, veterinarians Luciano Caixeta and Cainan Florentino parsed the details of their ketosis research. Both have practiced veterinary medicine and advanced their educations further. Caixeta has a PhD and is an Associate Professor of Dairy Production Medicine at the university’s College of Veterinary Medicine, and Florentino is a third-year PhD student there.
“As a veterinarian, I got sick of treating the same dairy diseases, which are very preventable,” said Caixeta. “So, I decided to study more about them.” He said ketosis specifically has gotten a bad reputation, and there are a lot of misconceptions about the condition.
Florentino said ketosis screening on-farm has become a common practice. It is typically accomplished by measuring ketone bodies in blood or urine. The diagnostic threshold for assigning a ketosis diagnosis (hyperketonemia) is greater than or equal to 1.2 mmol/L of beta-hydroxybutyrate (BHB) in blood or 15 mg/dL acetoacetate in urine. Both tests deliver results in less than a minute.
But managing illness associated with ketosis is not as simple as screening every cow and treating those above a certain level. The research duo has found that a number of intersecting factors come into play in solving the ketosis puzzle, including:
(1) A ketosis screening protocol should be done within the first week postpartum. Clinical ketosis in the first week of life has been shown to significantly reduce milk production, impair reproductive efficiency, and increase the likelihood that cows will leave the herd. But the researchers found that by the second week postpartum, some cows will post high readings (example: BHB of 1.7 mmol/L) but will be milking heavily, eating well, and not sick at all. So, a high reading in week 2 is much less predictive of a problem that needs treatment.
(2) Looking beyond a BHB reading of 1.2 mmol/L, a cow’s overall health can tell you more than the categorization. They said a high BHB reading, even in week 1, is not absolutely declarative of a problem. “If she’s not sick and is milking well, she’s showing that she’s coping with this new physiological state, using all that she has available to overcome the challenge of lactation, and is succeeding at it,” stated Caixeta.
(3) Recovering rumination time after calving can be an indicator of high milk yield, even when a cow is in a high state of ketosis. Longer rumination time has been shown to positively correlate with postpartum health and performance. In one study, Florentino shared that all cows with hyperketonemia (not considering whether or not they were treated for ketosis) produced significantly more milk than their herd mates without ketosis. In fact, the group with the highest rumination time produced 14 pounds more per day over the first 3 months of lactation than their non-ketotic herd mates that also had high rumination times.
(4) Rumination time prepartum can help identify cows with increased risk of ketosis-related sickness postpartum. They found that cows with lower prepartum rumination times were at 18% greater risk of becoming sick in the first week postpartum. Thus, low rumination time prepartum could flag cows that should be screened for ketosis and potentially treated.
(5) Treating hyperketonemic cows with low rumination time can rescue milk production in early lactation. Based on their research results, not all cows need treatment (typically oral propylene glycol for 3 days) for ketosis. They found that in the first 18 weeks postpartum, cows with low rumination times did benefit from treatment, and produced about the same amount of milk as cows without ketosis, but more than ketotic cows that were not treated. However, no positive effect from treatment was realized when cows had high rumination times. Both treated and untreated hyperketonemic cows produced more milk than cows without ketosis.
Caixeta advised against evaluating every fresh cow in the herd for ketosis. Rather, screening is more useful when applied with other factors, like cows with low prepartum rumination times, and fresh cows that are clinically sick. Screening a subset of fresh cows every 2-3 weeks also has value in ongoing herd surveillance of how cows are transitioning, and/or evaluating ration changes.
He said ketosis should be viewed more as a metabolic snapshot and physiological condition of fresh cows, rather than a disease. Often, cows can navigate the condition and perform very well. “If you screen every cow at 5 days in milk, you’re going to find a lot of cows with high BHB, but doing just fine,” he declared.
