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Studies on Milk Fever in Dairy Cows. V. The Effect of Massive Oral Doses of Vitamin D on Absorption, Excretion, Retention and Blood Levels of Calcium and Phosphorus¹

Department of Dairy Science, Ohio Agricultural Experiment Station, Wooster and UT-AEC Agricultural Research Program, Oak Ridge, Tenn.

ABSTRACT

This study is concerned with changes in the physiological behavior of calcium and phosphorus when massive oral doses of vitamin D are fed to cattle.

Recently Hibbs and Pounden (13) have shown that 30 million units per day of vitamin D fed 3–8 days prepartum prevented milk fever in mature cows with previous milk fever histories. The protection afforded by vitamin D was attributed to its calcemic effect, whieh was indicated by the relatively high blood calcium level maintained during the critical postpartum period. Other studies (24) have suggested that the increased blood calcium level was not due to parathyroid stimulation, because parathyroid activity was suppressed after 7 days of vitamin D feeding at thirty million units per day. In support of this, various workers (1, 15) using other species have found that calcemic doses of vitamin D increased absorption of calcium from the intestine, but parathyroid hormone secretion actually declined (1) and parathyroid size decreased (16).

¹ Journal article No. 34-56 of the Ohio Agricultural Experiment Station. Approved by the Assoc. Director April 17, 1956.