The importance of electrolyte balance in animal nutrition

Dear colleagues,

As the maintenance of acid-base balance is essential for life, there are different homeostatic mechanisms that act to ensure its constancy such as the endogenous buffer system based on phosphates, bicarbonates and proteins, the respiratory system that is key to the elimination of CO2 and the excretory (renal) system that modulates the excretion of electrolytes, bicarbonate, phosphate, and acids.

The three main fluid compartments of the organism are the intracellular, the interstitial and the plasma, where acid-base balance takes place:

• The intracellular is based on a relationship between the cationic strength of K and Mg and the anionic strength of phosphates, sulfates, and proteins.
• The interstitial extracellular is based on a relationship between the cationic strength of Na and the anionic strength of carbonates and Cl.
• And the plasma where a balance is maintained between the cationic strength of Na and the cationic strength of Carbonates, Proteins and Cl.

Diet can have a direct impact on acid-base balance, either by containing acids or potentially acidic substances, or by the buffering capacity it provides and the most common way to estimate the buffering capacity of the diet is to calculate its electrolyte balance.

The most used formula for measuring electrolyte balance takes Na, K and Cl into account:

Electrolyte balance (mEq/kg) = (Na/23 + K/39 – Cl/35.5) x 1000.

Although there are more precise formulas, which are necessary in cases where, for example, one works with ingredients rich in inorganic sulfur such as whey:

dUA(Patience, 1990) (mEq/kg) = (Na/23 + K/39 + 2xCa/12 + 2xMg/24.3 – Cl/35.5 – 1.8xP/31 – 2xS/32 ) x 1000.

The lower the value, the more acidogenic the diet, and vice versa, the higher the value, the more alkaline.

The recommendations for an optimal Electrolyte Balance for poultry and swine diets are usually between 200-250 mEq/kg.

Although it is always necessary to evaluate the metabolic situation of our animals, for example, it is positive to increase the value of the electrolyte balance >250 mEq in birds that suffer an excess of heat to control with carbonate the respiratory alkalosis produced by the loss of CO2 or to reduce the electrolyte balance <200 mEq in weaned piglets where their capacity of acidification of the digestive tract is limited, in laying hens it is also important to adjust very well the electrolyte balance to have a correct mobilization of calcium.

We also want to remind that the current tendency to reduce the percentage of protein in diets, for economic reasons, formulation precision, intestinal health, or environmental reasons, also reduces the electrolyte balance, although the formulas usually used do not take this into account.

To conclude, we are pleased to attach this week an interesting article where we evaluate how Electrolyte Balance affects piglets.

Enjoy the article!