Studies on Milk Fever in Dairy Cows. II. The Effect of Vitamin D on Some of the Blood Changes in Normal and Milk Fever Cows at Parturition

Abstract

Many of the usual blood changes occurring at parturition and in milk fever have been extensively investigated. Since Little and Wright (24) reported low blood calcium values ill COWS with milk fever much attention has been given to various mineral constituents of the blood. It appears that when an explanation is found for the changes in the mineral constituents of the blood and a way to prevent those changes can be devised, the mystery Of the milk fever syndrome will be solved. Since the report of Little and Wright (24) numerous reports have been submitted dealing with total calcium (1, 2, 10, 11, 12, 14, 15, 17, 24, 25, 27. 32, 33, 36) and diffusible calcium (15, 27, 30, 33) in the blood of normal and milk fever cows at parturition. All are in agreement that a marked decrease in both total and diffusible calcium occurs in milk fever. A sharp drop in blood inorganic phosphorus in milk fever-has been repeatedly reported (2, 11, 14, 15, 27, 29, 30, 33, 36). In contrast to serum calcium and phosphorus, serum magnesium is said to increase during milk fever (1, 2, 15, 23, 29, 30, 31, 33). The work of Mattick and Little (26) suggests some benefit in preventing the fall of blood calcium and phosphorus at parturition as the result of feeding cod-liver oil. The present paper is a report of s~udies covering the effect of irradiated yeast feeding on some of the blood changes at parturition and in milk fever, made in connection with the experiment described in the preceding paper (20) involving the effect of feeding vitamin D in the form of irradiated dry yeast on the incidence of milk fever.