Effect of dietary aflatoxin on vitamin D3 metabolism in chicks

Male broiler chicks were fed diets containing either O (control) or 2.5 p.p.m. aflatoxin (toxin) for four weeks. A group of eight birds fed each diet was infected intravenously with radioactive vitamin D3 (D3) and a second group with radioactive 25-hydroxy vitamin D3 (25-OH D3). Plasma was obtained 24 hr. after dosing with D3 and 6 hr. after dosing with 25-OH D3. The vitamin D metabolites were extracted from the plasma an chromatographed on Sephadex LH-20 for separation. The four peaks of radioactivity separated corresponded to D3, 25-OH D3, 24,25-dihydroxy vitamin D3 (24,25-(OH)2D3) and 1,25-dihydroxy vitamin D3 (1,25-(OH)2D3). Percentages of radiation in each peak were (1) controls given D3--6.55, 64.30, 5.94 and 4.04; (2) toxin given D3--10.05, 56.96, 8.95 and 4.68; (3) control given 25-OHD3-2.16, 85.80, 4.11 and 2.04; and (4) toxin given 25-OH D3--1.53, 79.84, 5.56 and 2.14. The only significant differences between the control and toxin groups were in D3 and 24,25-(OH)2D3 in chicks given D3. Even these changes were small and the data would suggest that feeding 2.5 p.p.m. aflatoxin for four weeks does not greatly alter vitamin D metabolism.