Historically in the dairy industry, rates of clinical hypocalcemia (milk fever) and ketosis were high. More recently dairies have done a better job controlling these two disorders through more precise nutrition, appropriate pen moves and better facilities. While a dairy producer might not see high rates of clinical ketosis and milk fever, these two disorders might still lurk under the surface at a subclinical level, causing a negative economic impact on the farm.
A cow with clinical hypocalcemia is likely near calving and unable to rise due to blood calcium levels. If your veterinarian analyzed blood from these cows, blood calcium levels would be below normal. Research has shown on most farms, 50% of more mature cows are affected by subclinical hypocalcemia. This is defined as a cow that is still able to rise, but has a reduced blood calcium level (less than 8.5 mg/dL) within 24 to 48 hours after calving.
Even though clinical hypocalcemia incidence might be low on your farm, the rate of subclinical hypocalcemia could still be high and negatively affecting your mature cows. If you aren’t convinced, take blood samples from at least 10 mature cows within 24 hours after calving to see where you stand.
A cow with clinical ketosis is a cow that has a reduced appetite, lethargy and high circulating blood ketone levels. This typically occurs within the first 21 days after calving. If your veterinarian analyzed blood from these cows, you would typically see levels of blood ketones above 3.3 mmol/L.
Subclinical ketosis is much more common. It is defined as a cow that does not appear sick and has a normal appetite but has blood ketone levels between 1.2 and 3.3 mmol/L. Some research suggests for every one cow affected by clinical ketosis, there are potentially five more cows affected by subclinical ketosis, but this varies from farm to farm. If you still aren’t convinced subclinical ketosis is an issue, obtain a blood ketone meter and draw blood twice weekly from cows three to 16 days in milk. Make sure you share all these results with your nutritionist and veterinarian.
With both subclinical hypocalcemia and ketosis, cows might never require treatment. At first glance, producers might not be able to notice anything wrong with these cows unless they conduct more in-depth testing.
Why Does it Matter?
First of all, ketosis and hypocalcemia can occur at high levels without obvious signs.
Second, the downstream effects cannot be understated. Because both diseases predispose cows to other transition issues, they are considered gateway disorders. Subclinical and clinical hypocalcemia predispose cows to mastitis, metritis and ketosis in the first 30 days in milk. Ketosis predisposes cows to metritis and displaced abomasum. Both diseases are financially important because they affect first-service conception rates, peak milk levels and increase risk of culling or death in the first 60 days in milk.
Consider paying closer attention to prefresh and dry cow groups to maximize fresh cow health, increase early lactation production, improve reproduction and reduce cows culled or dead by 60 days in milk. Create the team approach between your veterinarian, farm management and nutritionist to make a plan to minimize the impact of these disorders. Look below the tip of the iceberg to find where your dairy could be losing money.
Gabe Middleton is a partner with Mel Wenger at Orrville Veterinary Clinic, Orrville, Ohio. He serves bovine, equine, small ruminant and small animal clients.
Note: This article appears in the January 2018 magazine issue of Dairy Herd Management.