In layman’s terms,what does DCAD mean? DCAD stands for dietary cation-anion difference. It is a simple calculation of adding together the milliequivalents of dietary cations (sodium + potassium) and subtracting the sum of the milliequivalents of dietary anions (chloride + sulfur).
This is the most popular equation, but other equations do not include sulfur, so it is important to know which equation was used to calculate DCAD.
How is it measured?
Accurate, consistent ration DCAD can only be measured and monitored by conducting feedstuff wet chemistry analysis for the minerals in the equation.
What impact does it haveon a ration?
DCAD does not necessarily impact the ration directly, but it has strong influences on the cow. As the DCAD becomes more negative, the cow is forced into a mild acidosis, which is desirable at certain stages of her life – like the three weeks prior to calving.
As DCAD becomes more positive, the cow develops more blood-buffering capacity, which is desirable in fresh and high-producing cows.
What does this do in the ration?
Negative DCAD causes mild acidosis, which is desirable in the prepartum transition period to help mobilize calcium from bones and prevent clinical and subclinical milk fever as well as maintain immune function. A DCAD of -8 to -12 meq per 100 g ration dry matter is recommended.
Positive DCAD increases blood buffers and is needed postpartum when the cow is producing a lot of metabolic acids. (High milk production, fat mobilization and increased respiration increase blood acid load.) The more milk you expect, the higher the DCAD should be.
Recommendations are for postpartum DCAD levels to be +35 to +45 meq per 100 g ration dry matter for high-producing cows, +30 to +35 for mid-lactation cows (not groups of cows) producing less than 85 pounds of milk and +25 to +30 for late-lactation cows. Research shows that higher DCAD also optimizes milk and component production, along with feed efficiency.
What percentage of your clients do you think really understand this value?
We expect that about a third or fewer of dairy producers and nutritionists truly understand the value of DCAD balancing. If it was correctly understood, the concepts would be used more routinely due to the significant impact proper ration DCAD has on cow health and productivity. PD
Elliot Block
Senior Manager of Technology
Arm & Hammer Animal Nutrition
