UV-B light stimulates the production of Vitamin D3 in Atlantic salmon

Vitamin D 3 was analysed in fish muscle during two separate production trials with Atlantic salmon in the freshwater phase. Each trial consisted of two groups exposed to UV-B light and two control groups. Fish were sampled at the start of the trial and after approximately 30 and 70 days. The groups exposed to UV-B light had 2,5 to 6 times higher Vitamin D 3 in the muscle after 4 weeks and more than 5 times as much after about 10 weeks than the control groups. The study suggests that Atlantic salmon in the freshwater phase synthesize pre-vitamin D 3 from 7-dehydrocholesterol using UV-B light in a larger extent than previously thought. In today's salmon farming, where more of the farming occurs in closed and submerged facilities with no or limited access to UV-B from natural sunlight, this knowledge is important.