UVB exposure is an effective approach to fortify egg yolk with vitamin D₃.

<p>Changes between basal and final vitamin D₃ (A) and 25(OH)D₃ (B) contents in egg yolk dry matter (DM) and final contents of vitamin D₃ (C) and 25(OH)D₃ (D) in egg yolk DM and in in non-treated (-UVB) or UVB-treated (+UVB) hens that were fed either a vitamin D₃-deficient (-D₃) or vitamin D₃-adequate diet (+D₃), respectively. Data represent mean ± SD (n = 9). Data were analyzed by two-way ANOVA with the classification factors were UVB exposure, vitamin D₃ in the diet, and the interaction between both factors. (A) Effect of UVB: <i>p</i><0.001, vitamin D₃: <i>p</i><0.001, UVB × vitamin D₃: <i>p</i><0.05. (B) Effect of UVB: <i>p</i><0.001, vitamin D₃: <i>p</i><0.001, UVB × vitamin D₃: <i>p</i><0.001. When two-way ANOVA (2WA) revealed a significant interaction between UVB x vitamin D₃ individual means of the groups were compared by post-hoc test. Asterisks within one diet group (-D₃ and +D₃) indicate a significant difference between -UVB and +UVB groups, *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001.