| Abstract: | Plasma levels of vitamin D3 were determined in a group of 10 cows housed indoors and exposed during the winter to ultraviolet irradiation (UVR). Exposure to UVR was associated with marked rises in plasma vitamin D3 concentrations. The pattern and magnitude of the plasma vitamin D3 response to UVR exposure in sheep raised in total confinement was also investigated. Exposure to sun lamps produced a significant increase in sheep plasma vitamin D3 concentrations. There was no significant difference in the plasma levels of vitamin D3 due to length of time of exposure to UVR. |
