Interrelationships between dietary concentrations of sodium, potassium and chloride in laying hens

Twelve diets, representing the factorial combination of two concentrations of Cl- (0.8 and 1.4 g/kg), three concentrations of Na+ (0.5, 1.1 and 1.7 g/kg) and two concentrations of K+ (7 and 12 g/kg) were fed to groups of laying hens for 24 weeks and records taken of their productivity. Different concentrations of Na+, K+ and Cl- showed highly significant interactions which were always similar. Thus, a deficiency of Na+ (0.5 g Na/kg) was aggravated by the restriction of Cl- (0.8 g/kg), but was partly compensated for by supplementing the diet with K+ (12 instead of 7 g/kg). Without a sodium deficiency other interactions occurred; for example, the higher concentration of K+ became unfavourable if the other two ions were also supplied at the higher concentrations. These results show that, for the laying hen, the optimum concentrations of Na+, K+ and Cl- cannot be determined independently but depend upon the concentration of the two others in the diet.