Reduce the Economic Impact of Low Blood Calcium in Transition Cows

The impact of milk fever on dairy cow health and production is well-known. But milder forms of low blood calcium can also create problems for transition cows – and at significant cost. Joining us today on DairyLine is Dr. David Kirk, Dairy Technology Manager with Phibro Animal Health.

David Kirk: All cows, even first lactation heifers, are susceptible to hypocalcemia at calving, as the requirement for calcium increases dramatically from low, to meet her maintenance needs, to high, as colostrum and milk production begins.

Clinical hypocalcemia, or milk fever, is an expensive disease, with costs estimated as high as $344 per case. Fortunately, clinical milk fever occurs in only about 5 percent of fresh cows. But subclinical hypocalcemia, with serum total calcium of less than 8.5 mg/dl, but without clinical signs, has a much higher incidence rate, at more than 50 percent of postpartum animals.

Dr. Gary Oetzel of the University of Wisconsin School of Veterinary Medicine, in 2011, estimated the costs associated with subclinical hypocalcemia at $125 per case. When you combine the high incidence of subclinical hypocalcemia with this relatively conservative cost/case, the economic impact of subclinical hypocalcemia is far greater than clinical milk fever.

DairyLine: Dave, cows with subclinical hypocalcemia are also susceptible to other diseases. What should producers know?

David Kirk: We know cows suffering from clinical milk fever are at much greater risk of having a retained placenta or developing mastitis and metritis. Subclinical hypocalcemia is associated with increased risk of disease, as well.

Reports from a very large observational study conducted using blood samples taken from around 2,000 cows from herds across the U.S. and Canada showed strong associations of subclinical hypocalcemia with cow health, milk production and reproduction.

In those reports, cows with low serum total calcium during the week after calving had a three-fold greater risk of developing a displaced abomasum, produced about 5 ½ pounds less milk on first test day, and had lower first service conception rates. Other research, conducted at the University of Florida, indicated there was a strong association of subclinical hypocalcemia with increased incidence of metritis as well.

DairyLine: Phibro Animal Health has compiled some figures that illustrate the potential magnitude of the economic impact. Please share some of that data.

David Kirk: Recently, Dr. Jamie Jarrett, one of our Dairy Technology Managers in California, put together a nice example of the potential economic impact of subclinical hypocalcemia in a typical herd of 1,000 cows, with 45 percent first lactation animals. Using previously published estimates for disease costs and incidence rates of subclinical and clinical hypocalcemia, Dr. Jarrett estimated the combined costs of milk fever and subclinical hypocalcemia totaled over $90,000.

However, with that same dairy feeding a fully-acidified pre-fresh diet, the expected reduction in clinical milk fever and subclinical hypocalcemia will lower those combined costs to $16,000. That’s a potential savings of nearly $75,000 per 1,000 calvings achieved by feeding a negative DCAD diet to transition cows prior to calving.

DairyLine: For producers who may not be fully versed in negative DCAD diets, please provide a little background.

David Kirk: DCAD, or Dietary Cation-Anion Difference, is essentially the balance of positively-charged minerals, or cations, with negatively charged minerals (anions) in the diet. The effective cations are potassium and sodium. The effective anions are chlorine and sulfur.

Interestingly, the DCAD of the diet impacts blood chemistry. Diets that are relatively high in potassium and sodium – high DCAD – make the blood more basic, or raise blood pH. By increasing blood pH, these high DCAD diets impair the cows’ own ability to maintain proper blood calcium levels around the time of calving, therefore increasing the risk of developing clinical or subclinical hypocalcemia.

The opposite happens when a negative DCAD diet is fed. Diets that are relatively high in chlorine and sulfur – low DCAD – make the blood more acidic, or lower blood pH.

By reducing blood pH, the negative DCAD diets actually enhance the cows own ability to correct blood calcium concentrations around the time of calving. That means, by feeding a negative DCAD diet before calving we can reduce the incidence of both clinical and subclinical hypocalcemia.

DairyLine: What role does Phibro Animal Health’s specialty nutritional product, Animate®, play in reducing the risk of subclinical hypocalcemia?

David Kirk: Animate is an excellent source of chlorine and sulfur, the anions that lower DCAD. When fed as part of a properly balanced pre-fresh diet for at least 21 days before calving, Animate will help reduce the incidence of both clinical and subclinical hypocalcemia.

Research has shown that the lower we reduce the DCAD content of the pre-fresh diet, the greater the concentration of blood calcium at calving, as long as intake isn’t reduced. Because Animate is highly palatable, it can be used to fully acidify the pre-fresh diet without fear of lower dry matter intake.

These fully-acidified pre-fresh diets with Animate help to significantly reduce the incidence of subclinical hypocalcemia and the negative impacts on fresh cow health, production and reproduction associated with subclinical hypocalcemia.

DairyLine: Thanks, Dave. That’s Dr. David Kirk, Dairy Technology Manager, with Phibro Animal Health.

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