Calculating the Dietary Cation-Anion Balance for Healthy Cows

BicarZ -Dietary Cation-Anion Balance- DCAB

The Dietary Cation-Anion Balance (or DCAB) is conventionally used to take into account the major parameters likely to modify the acid-base balances in the ruminant organism. The DCAB is an indicator of the effect of a food or diet on the acid-base homeostasis of the animal.

Highly positive DCAB leads to metabolic alkalinization

One of the biochemical parameters of metabolic alkalinization is a urine pH value over 8. Ruminants, due to their consumption of feed rich in alkaline elements (mainly K), tend physiologically towards metabolic alkalosis.

A negative DCAB causes metabolic acidosis

This is characterized in particular by a urine pH value below 7.5 (and up to 5.5 in cases of severe metabolic acidosis).  Metabolic acidosis is a pathological condition inducing, among other things, a decrease in ingestion and significant urinary calcium loss. It should also be noted that metabolic acidosis (and therefore a low urinary pH) can occur in other situations too, such as ketosis, severe diarrhea ...

 

How to calculate the Cations-Anions Food Balance? 

To calculate the Dietary Cation-Anion Balance of the ration, the milliequivalents of positively charged cations (sodium and potassium) must be deducted from the negatively charged anions (sulphur and chlorine). We can calculate the value of the Cation-Anion Balance of any ration and feed if we know the concentrations of these four elements. If there are more than milliequivalents of cations, the charge will be positive and if there are more anions, the charge will be negative.

DCAB = Na + K – Cl – S en mEq/kg.

What is the technical explanation? Sodium [Na+] and potassium [K+] have an alkalizing effect, whereas chloride [Cl-] and sulphur-containing ions [S, in different chemical forms] have an acidifying effect. 

What is the DCAB value of Bicar® Z?

The molecular weight of Na is 23 g. 

Bicar®Z contains 270 g of Na/kg without Cl, K or S. 

So its DCAB value is 270 g /23 g, i.e. 11.7 BACA equivalent / kg of sodium bicarbonate, or 11,700 mEq of DCAB / kg of sodium bicarbonate. 

 

This is why the effect of 1% of Bicar®Z in a ration for dairy cows (i.e. 250 g/d) will therefore be +117 mEq of DCAB and +2.7 g of sodium per kg of DM.

The Dietary Cation-Anion Balance varies depending on your animal

What is the ideal Cation-Anion balance for dairy cows? 

Dietary Cation-Anion Balance-DCAB

The DCAB recommendations of dairy cows differ according to the sources. US nutritionists prefer maximum intake and production, which explains their choice of a fairly high DCAB:

  • 120-150 mEq/kg DM according to INRA (French National Institute for Agronomic Research).
  • In the USA, the recommendations are well above 250 mE/kg of DM.
  • 280-370 mEq/kg MS (Hu 2004 - Beede 2005)
  • 350-400 mEq/kg in early lactation (Lean 2013)
  • 275-450 (Oetzel 2017)

Increasing the sodium level to 0.4% of the ration and the DCAB to 400 mEq/kg DM (Dry Matter) is equivalent to providing 250 g of sodium bicarbonate (and more as required); ensure that the potassium level is at least 1.5% of the DMI (Dry Matter Intake).

 

Stage of development

Ideal DCAB value (mEq/kg DM)

Beginning of drying out 

As low as possible

Calving preparation

As low as possible, preferably negative

Freshly calved cow

Between 200 and 400 

Beginning of lactation

Between 200 and 400 

Halfway through lactation

between 200 and 400 

End of lactation

Between 200 and 400 

In case of heat stress

between 300 and  500 

 

What is the ideal Cation-Anion balance for a young bull?

Stage of development

Ideal DCAB value (mEq/kg DM)

Young bull at the start of fattening 

Between 200 and 250 

Young bull in the final stage

Between 220 and 280 

Young bull in heat stress situation

Between 250 and 300