Research in the last decades has revealed that vitamin D is essential for physiological functions “beyond bone” and displays important functions for reproduction, cellular development, and immune system function, to name a few. From an evolutionary perspective, significant amounts of vitamin D are obtained from exposure to sunlight and vitamin D photosynthesis in the skin. Pigs that are housed indoors, especially younger animals, are frequently found to have a low vitamin D status when compared to pigs housed outdoors during summer conditions, even when receiving “typical” levels of vitamin D3 supplementation in the diet.
In this brief review, recent research is provided to support recommendations for achieving an optimum vitamin D status for modern, lean genotypes housed indoors; and the benefits of dietary supplementation using 25-OH-D3 to safely achieve healthy plasma levels of 60 – 90 ng/ml of 25-OH-D3 are demonstrated.
