Magnesium Requirement of Guinea Pigs and Rats

Abstract

Weanling guinea pigs and rats were fed diets deficient in magnesium and of variable calcium and phosphorus content. The growth rate, incidence of visible calcium phosphate deposits, mortality and other symptoms of magnesium deficiency were noted. Excessive intake of phosphorus was observed to accentuate the symptoms of magnesium deficiency. The injurious effect of phosphorus, when added to a diet low in magnesium, was more marked than that of calcium but the effect was largely eliminated by adequate magnesium. When the diet contained 0.9% of calcium and 0.4% of phosphorus the magnesium requirement was determined to be 80 mg per 100 gm of diet. When phosphorus was elevated to 1.7%, the requirement rose to 240 mg. The symptoms of magnesium deficiency in the guinea pig include slow growth, soft-tissue calcification, stiffness in the hind limbs, exostosis of the mandibles, overgrowth of the molars, and erosion, softening and decay of the incisors.