UVB Exposure of Farm Animals: Study on a Food-Based Strategy to Bridge the Gap between Current Vitamin D Intakes and Dietary Targets

Vitamin D deficiency is a global health problem. This study aimed to investigate the efficacy of ultraviolet (UV) B radiation for improving vitamin D(3) content of eggs and meat. In a two-factorial design hens that received diets with 0 (-D(3)) or 3,000 IU (+D(3)) vitamin D(3)/kg were non-exposed (-UVB) or exposed to UVB radiation (+UVB) for 3 h daily over 4 weeks. Data show that UVB radiation was very effective in raising the vitamin D(3) content of egg yolk and meat. Egg yolk from +UVB/−D(3) hens had a higher vitamin D(3) content (17.5±7.2 µg/100 g dry matter (DM)) than those from the –UVB/+D(3) group (5.2±2.4 µg/100 g DM, p<0.01). Vitamin D(3) content in egg yolk of vitamin D(3)-supplemented hens could be further increased by UVB radiation (32.4±10.9 µg/100 g DM). The content of 25-hydroxyvitamin D(3) (25(OH)D(3)) in the egg yolk also increased in response to UVB, although less pronounced than vitamin D(3). Meat revealed about 4-fold higher vitamin D(3) contents in response to UVB than to dietary vitamin D(3) (p<0.001). In conclusion, exposure of hens to UVB is an efficient approach to provide consumers with vitamin D(3)-enriched foods from animal sources.