About 60 % of sodium is located in the soft tissues and body fluids; 40 % is present in the skeleton and bones. Sodium is a basic mineral element in blood serum and is the main cation regulating blood pH. Chlorine represents two thirds of anions in blood. Sodium and chlorine are important for maintaining osmotic pressure, acid-base balance and exchange mechanism through the cell membranes (sodium pump).
Sodium also ensures distribution of water throughout the body; moreover it plays a role in nerve impulse transmission, muscles contraction and the rhythmic maintenance of heart action; sodium is also necessary for the assimilation of amino acids and mono - saccharides in the small intestine. Chlorine is a component of hydrochloric acid, indispensable for digestion. Finally, sodium chloride is important for appetite, feed intake, digestion, in milk secretion, growth, reproduction, resistance to heat and diseases.
Main sources

Sodium chloride
Sodium bicarbonate Sodium sulphate anhydrous
Quality and selection parameters
The optimal particle size and density depend on the use in various types of feed as premix, mineral feed stuffs, complementary or complete feed. Granulariry and bulk density of the product are important parameters for the mixing behaviour. By treatment with anti-caking agents like E 530 magnesia or E 554 sodium aluminium silicate or E551 silica at max. 20 g / kg, or crystal modifiers like E536 potassium ferrocyanide or E535 sodium ferrocyanide at max. 80 mg/kg  the flowability of sodium salts can be improved. The presence of chloride in the sodium source may be another selection criteria.
Analytical methods
Determination of Cl according to ISO 2481 or ISO 6227
NaCl assary: calculation by difference with determination of humidity - insolubles - sulphates - calcium - magnesium.
Conversion Factors
Na x 2,543 = NaCl
NaCl x 0,393 = Na
Na = Cl x 0,648