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

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Abstract
A study was made of the serum Ca, P, Mg, and phosphatase in the blood of normal and milk fever cows at parturition when fed various amts. of vitamin D. Although 1 million units of vitamin D fed daily to cows for 30 days before parturition doubled the vitamin D content of the blood and 2 million units fed daily for 2 weeks caused a 4-fold increase in the blood level, no significant changes in the blood serum Ca, P or Mg were observed. No difference in the composition of colostrum between normal and milk fever cows was noted. The blood serum Ca-Mg relationship is discussed in regard to its possible effect on the symptomatology of milk fever. Before increases in the serum Ca and P level of the blood can be obtained, sufficient to lower milk fever incidence, apparently more than 2 million units of vitamin D must be fed daily before parturition. Expts. are in progress to determine the effect of larger amts. of vitamin D on the blood picture and on the incidence of milk fever.