Mammary transfer of vitamin D3 in the rabbit doe

Mammary transfer of vitamin D3 from a single intravenous injection containing 100 000 IU vitamin D3 in ethanol, was studied in lactating rabbit does. Significant amounts of the injected vitamin D3 appeared in the milk of does. The highest concentration was observed in the first milk sampling (24 h after administration) which was followed by a decreasing pattern in the five postinjection days. Vitamin D3 concentration in the neonate tissues were smaller than in their dams. In the maternal tissue the highest concentration occurred in the liver, whereas muscle had the lowest value. Among the various neonatal tissues liver contained the highest amounts although in the other tissues appreciable amounts of vitamin D3 were recovered.