Calcium and magnesium metabolism in calves. 2. Effect of dietary vitamin D and ultraviolet irradiation on milk-fed calves

Publisher Website
Google Scholar
Abstract
The addition of a supplement of 300-400 IU of vitamin D3/day to the diet of milk-fed calves reduced the rate of decrease in Ca utilization as the calves got older and prevented the plasma-Ca level from falling when the plasma-Mg level fell. The addition to the diet of 70,000 IU of vitamin D3/day or irradiation of the calves with UV light greatly improved the utilization of Ca both in calves previously receiving no vitamin D and in those receiving 300-400 IU of vitamin D3/day. The mean fecal excretion of Mg increased from 32% of the dietary Mg at about 3 weeks of age of 86% at about 16 weeks of age, after which it did not change greatly. Neither the addition of vitamin D to the diet nor irradiation of the calves with UV light had any appreciable effect on this excretion.