Studies on Milk Fever in Dairy Cows. IV. Prevention by Short-Time, Prepartum Feeding of Massive Doses of Vitamin D

Calcium and phosphorus metabolism in ruminants with special reference to parturient paresis

“…Large oral doses (20-30 million units) of vitamin D have been used successfully to prevent parturient paresis (89,91). To be effective, however, treatment has to start at least 3 d before parturition and must not be continued for more than 7 d, or toxic effects appear (49,129).…”

Vitamin Tolerance of Animals

“…Parenteral administration of 15 million IU of vitamin D 3 in a single dose caused toxicity and death in many pregnant dairy cows . On the other hand, oral administration of 20 to 30 million IU of vitamin D 3 daily for 7 days resulted in little or no toxicity in pregnant dairy cows (Hibbs and Pounden, 1955). Napoli et al, (1983) have shown that rumen microbes are capable of metabolizing vitamin D to the inactive 10 keto-19-nor vitamin D. Parenteral administration would circumvent the deactivation of vitamin D by rumen microbes and may partially explain the difference in toxicity between oral and parenteral vitamin D.…”

Effect of Parturient Paresis and the Oral Administration of Large Prepartal Doses of Vitamin D on Blood Calcium and Phosphorus in Dairy Cattle

“…13 The lowering of milk fever incidence at the 10 million-units- per-day level of vitamin D feeding, and the complete protection resulting from the 20-and 30-million-unit level (TABLE 2),13 were accompanied by the maintenance of blood calcium and phosphorus a t levels higher than the controls during the critical postpartum period (TABLE 3 and FIGURE 6). 13 The relatively high blood-calcium level maintained during the critical postpartum period is believed to be the cause of, or a t least an indicator of, the protection against milk fever. The mode of action of vitamin D in eliciting the increased blood calcium, much of which was apparently due to ionic calcium,17 however, is not completely understood.…”