Arm & Hammer Animal and Food Production
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Optimizing the transition period with negative DCAD in prepartum diets.

Posted February 27, 2020 by Dr. Ruby Wu, Ruminant Technical Services Manager

The transition period in dairy cows is one of the most important determinants of productivity and postpartum health, setting the stage for the entire lactation. Metabolic disorders that crop up during transition are extremely costly. A single displaced abomasum can cost you $340. One case of milk fever can be over $300 and you’ll lose approximately $145 on a case of ketosis.1 But even then, those are just the acute costs. Poor start-up milk, high incidence of metritis and low pregnancy rates could also be weighing on productivity.

Fighting ketosis and milk fever in cows.

While it’s obvious that clinical cases of hypocalcemia, uterine diseases and retained placentas negatively affect your bottom line, subclinical metabolic disorders are also productivity-killers. This makes the transition period critical to lactation success—the smoother the transition, the better.

One proven way to reduce cases of milk fever and other metabolic disorders before they even start? Negative DCAD (dietary cation anion difference) prepartum.

DCAD for transition cow success.

DCAD measures the levels of macrominerals in the diet, including potassium (K) and sodium (Na)—the positively charged cations—and chloride (Cl) and sulfur (S), the negatively charged anions. 

DCAD Balancing

This number is important because it informs what your cows may be missing in their diet at any given time. Prepartum, cows need more chloride and sulfur—or a negative DCAD—to increase their blood calcium at calving.  However, the trick is to bring DCAD down while maintaining palatability.

How do DCAD diets work?

Essentially, a negative DCAD of -8 to -12 meq/100g metabolizes the calcium transfer from bone to the bloodstream, increasing blood calcium and reducing the likelihood of milk fever.

DCAD bubbles

Optimizing transition cow nutrition.

Follow these steps to reach optimal negative DCAD levels.

  1. Conduct a chemical analysis to know the exact DCAD levels of your feed ingredients and forages.
  2. Decrease dietary potassium and sodium as much as possible.
  3. Adjust DCAD levels to -8 to -12 meq/100g dry matter by adding a palatable anion source to the ration.
  4. Formulate magnesium levels to be above 0.40% of the total dry matter.
  5. Monitor urine pH to a target range of 6.0 to 6.8.

Finding the right anion source.

While there are many products on the market, not all of them are scientifically backed or contribute to other important prepartum diet factors. This calculator can help you compare the costs of different anion sources.

BIO-CHLOR is the only anion source that delivers negative DCAD to consistently acidify cows, while also optimizing metabolizable protein (MP) and driving microbial growth that supports rumen function. Plus, it’s accepted by the cow and supports dry matter intake prepartum so you spend less time diagnosing off-feed issues postcalving.

It’s also extensively researched, with promising results showing BIO-CHLOR drastically reduced incidence of metabolic disorders in 13,000 cows.2


BIO-CHLOR Health Benefits chart

To learn more about how negative DCAD can improve transition health, find an ARM & HAMMER™ rep near you.



2 Robert Corbett. ARM & HAMMER Animal Nutrition, 2001. Data on file.

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