FIGURE 2.
Vitamin D3 metabolite plasma concentrations of 78-wk Hy-Line Brown laying hens fed different concentrations of dietary vitamin D3. (A) Cholecalciferol [vitamin D3; 400 and 800 IU treatment concentrations were below limit of detection and were not determined (ND)] (B) 25-hydroxycholecalciferol (25-OH-D3) (C) 24,25-dihydroxycholecalciferol [24,25-(OH)2-D3] (D) ratio of 24,25-(OH)2-D3/25-OH-D3 presented as a percentage. Blue squares denote standard NRC range vitamin D3 concentrations (400 and 800 IU D3/kg) in diet (n = 4), and red diamonds denote super-dose concentrations of vitamin D3 (14,000, 20,000, and 36,000 IU D3/kg) in diet (n = 4). Samples were reported as means ± SEM. Samples with common letters were not significantly different from each other (general linear models, P < 0.0001). NRC, National Research Council; SEM, standard error of the mean.