All ketosis cases are not created equal, but diagnosing cows with Type 1 or Type 2 may make all the difference in treatment success. Heather White, Ph.D., at the University of Wisconsin – Madison Department of Dairy Science, has been studying ketosis in its two distinct and different forms: Type 1 (later-onset, typically clinical) and Type 2 (earlier-onset, typically subclinical).
According to the assistant professor of nutritional physiology, understanding how the cow’s metabolism acts and reacts in each situation is key to successful management and treatment of the disease.
“We used to lump all ketosis into one group; then we realized that depending on when the disease onset occurred, the etiology was a little different, and we should treat it differently,” White says.
Fat cow versus skinny cow
A blood test is the most accurate way to diagnose cows with subclinical or clinical ketosis, but eyeing up the dry cow and fresh pens can be helpful in identifying at-risk cows.
White defines Type 1 ketosis as the traditional, typically clinical disease, often occurring three to six weeks after calving, around the same time as peak milk production. These cows, which run blood beta-hydroxybutyrate (BHBA) levels above 3.0 mmol per L, tend to be very thin.
“Basically, this is a cow that is milking off of her back to provide energy for glucose production – she is just doing it a little too well,” White explains. “These tend to be the high-producing cows that look like they are making a lot of milk. They will lose quite a bit of body condition score to supply those energy equivalents for milk production.”
Type 2 ketosis, on the other hand, tends to be the subclinical cases with BHBA levels between 1.2 and 3.0 mmol per L. In contrast, these cows were often overconditioned during the dry period or at the time of calving. Onset occurs within the first two weeks after freshening, and the disease may continue to linger at that level or progress to clinical ketosis.
Watch what you treat
White’s research shows that these two types of ketosis affect the cow’s metabolism in different ways, which is why it is important to treat the cow according to what her body really needs.
“With Type 2 ketosis, blood glucose and blood insulin are already elevated,” she says. “This is not the case with the Type 1.”
A cow with Type 1 ketosis has low blood glucose and benefits from an extra energy boost.
“We recommend half a bottle of dextrose (250 mL) in addition to three to four days of oral propylene glycol for clinical cows,” she adds. “That’s enough dextrose to give her that nudge and give her a little bit of glucose that is already made.”
White warns that administering the full 500 mL bottle of dextrose is simply too much and can, in fact, have negative impacts on the cow.
“If the cow’s blood glucose is too high, it sends messages to the liver to stop making glucose on its own,” she explains. “If the liver has received those stop signals, then it is no longer making glucose, and she will have a secondary crash when the blood glucose is decreased again.”
A half-bottle of dextrose is just enough to do the trick. White has seen some dairy producers warm up the bottle of dextrose, remove half of it and add other solutions like a Vitamin B complex. This way, the full contents of the bottle can be given intravenously without the worry of overdoing glucose. Though it may seem wasteful to throw away the remaining solution, she insists it is the best choice.
“It’s going to cost you more to give her that other half than to throw it away. We really want to keep the cow’s liver functioning,” she says. “To give her that other half of the bottle, we take a lot of risk of decreasing her own glucose production. We want to get her back to making glucose on her own.”
The goal is to “help the cow help herself” without shutting down liver metabolism.
For subclinical cases, propylene glycol alone is the preferred treatment over dextrose because these cows already have high glucose levels. Propylene glycol is effective because the liver must “work” in order to turn it into glucose. This keeps the liver active and encourages the cow to rely on her own regulatory mechanisms.
Ketosis management and prevention
White estimates that 20 to 45 percent of cows in U.S. dairy herds have or will be affected by ketosis – either clinical or subclinical – at some point in their lifetime. Left untreated, either form can lead to serious consequences.
Ketotic cows are 50 times more likely to leave the herd in their first 30 days in milk (DIM), and those that are not culled are more likely to suffer from displaced abomasum (DA), lower milk production and reproduction challenges.
Implementing a testing protocol can help to identify sick cows earlier and direct the course of treatment. White recommends a blood BHBA test over urine or milk tests because of its 95 percent accuracy and quantitative results.
In a matter of seconds, a small drop of blood can determine whether or not a cow is under or over the thresholds for subclinical or clinical ketosis. She recommends testing weekly and checking all fresh cows between five and 20 DIM at least once, or testing twice a week for herds with a higher prevalence.
Through her research, White has observed a large variance in the rate of ketosis on dairies. In a study of large, commercial dairies, one particular herd ranged from 10 percent to as high as 25 percent of cows with clinical or subclinical forms of the disease.
“This large variation supports the fact that we need to be aggressively testing so we can manage for the disease,” she adds.
The good news about ketosis is that we can control it.
“This disease has a big impact, but it is something we can definitely manage and treat,” White affirms. “With proactive detection, testing and treatment, we can decrease the prevalence on-farm and decrease negative impacts of the disease.” PD
PHOTO
According to Heather White, Ph.D., clinical and subclinical ketosis do not cause the same metabolic reactions in a cow, thus requiring different treatment protocols. Photo by Peggy Coffeen.
Peggy Coffeen
Editor
Progressive Dairyman
Can we use genomics to predict ketosis?
Genomics could be the crystal ball that allows dairymen to determine which cows are at higher risk for ketosis.
“Our lab is looking at genetic predisposition through genetic markers that will allow dairy producers to manage cows more intensely if they are more likely to get ketosis,” White says.
By knowing which cows are genetically prone to ketosis, producers can have a plan in place for getting them on the right track after calving. The concept is for this information to be part of the analysis that comes back from a genomics test.
The idea is not to eliminate these cows from the herd but rather to adjust management and nutrition to accommodate them.
“We don’t want to select against these cows because they are often high-producing cows, but what we want to do is identify a few markers,” she adds. “We can manage these cows differently to make sure they are set up for success when they freshen.”
White notes that this genomic-based management tool is not that far from becoming reality.
“We are getting pretty close. We have a list of candidate genes now from a small preliminary study,” she says. “We are moving into a study now that would look at 500 cows and correlate genetics with ketosis onset during the transition period.”
