Calcium Status Studies on Adult Sheep

Abstract

Experiments were conducted with sheep, maintained with a calcium-deficient diet, to evaluate methods for determining calcium status of mature animals. During a 10-week balance trial, animals fed the Ca-deficient diet exhibited a linear decrease in plasma calcium for 3 weeks, after which it returned to the initial level and remained so for the next 7 weeks. Plasma phosphorus increased with time, but urinary phosphorus excretion did not increase. After the balance trial, the Ca-deficient sheep were given, via intravenous injection, 100 mg and later 300 mg of phosphorus. In comparison with controls the treated sheep were observed to maintain lower plasma phosphorus peaks immediately after the injection of phosphorus. Renal arterial-venous difference in phosphorus levels were greater in Ca-deficient animals, and hence it is postulated that renal phosphorus clearance was greater in the Ca-deficient sheep.