Response of Growing Rats to Diets Varying in Magnesium,Potassium and Protein Content

Abstract

Summary

Dietary magnesium, potassium and protein interactions were studied in weanling rats. Growth rate, efficiency of feed utilization, and blood serum magnesium and calcium levels were significantly lower in rats fed a magnesium-deficient diet than in those fed a similar magnesium-adequate diet. A diet containing 4 times as much potassium (8132 mg/kg) increased the serum magnesium level 60% after 28 days (1.0 vs. 1.6 mg%) and 90% after 56 days (0.9 vs 1.7 mg%) indicating an inhibition by potassium of the reduction in serum magnesium associated with consumption of magnesium-deficient diet. Typical gross magnesium deficiency symptoms, including reddened ears and paws and convulsions lasting 1–5 minutes were observed, however, in all groups fed low magnesium diets regardless of potassium level. Diets containing 20% protein produced significantly greater growth rate than those containing 10% in the presence of adequate magnesium but not during magnesium deficiency. No histological lesions associated with treatment occurred even after 56 days on test despite the fact that gross magnesium deficiency symptoms appeared as early as one week on test.