LAUSR

Dietary iron (Fe) influences manganese (Mn) utilization in chickens fed with inorganic Mn-supplemented diet. This study aimed to determine if dietary Fe levels affect Mn utilization in broilers fed with organic Mn-supplemented diet. Nine hundred 8-day-old broilers were randomly assigned to 1 of 6 treatments in a 3 (Fe level) × 2 (Mn source) factorial arrangement after feeding Mn- and Fe-unsupplemented diets for 7 days. The broilers were fed the basal diets (approximately 28 mg Mn/kg and 60 mg Fe/kg) supplemented with 0, 80, or 160 mg/kg Fe (L-Fe, M-Fe, or H-Fe), and 100 mg/kg Mn from Mn sulfate (MnSO 4 ) or manganese-lysine chelate (MnLys) for 35 days. The H-Fe diet decreased ( P  < 0.05) body weight gain and feed intake as compared with L-Fe and M-Fe diets regardless of dietary Mn sources. Dietary Fe levels did not influence ( P  > 0.10) serum Mn concentration in MnLys-treated broilers, but serum Mn concentration decreased ( P  < 0.05) with dietary Fe increasing in MnSO 4 -treated broilers. The Mn concentration in the duodenum and tibia decreased ( P  < 0.05) with increasing dietary Fe levels regardless of dietary Mn sources, and MnLys increased ( P  < 0.04) these indices as compared with MnSO 4 . Dietary Fe levels did not significantly influence ( P  > 0.11) Mn concentration and activity and mRNA abundance of manganese-containing superoxide dismutase (MnSOD) in the heart of MnLys-treaded broilers, but the H-Fe diet decreased ( P  < 0.05) these indices in MnSO 4 -treated broilers as compared with M-Fe and L-Fe diets. The L-Fe diet increased ( P  < 0.001) duodenal divalent metal transporter 1 mRNA abundance when compared with the M-Fe and H-Fe diets on day 42, regardless of dietary Mn sources. The M-Fe and H-Fe diets decreased ( P  < 0.001) duodenal ferroportin 1 (FPN1) mRNA level when compared with the L-Fe diet in MnSO 4 -treated broilers, while dietary Fe levels did not significantly influence ( P  > 0.40) duodenal FPN1 mRNA abundance in MnLys-treated broilers. These results indicated dietary Fe levels decreased Mn utilization in MnSO 4 -treated broilers, but did not influence Mn utilization in MnLys-treated broilers evaluated by Mn concentrations in the serum and heart, and the activity and mRNA expression of heart MnSOD.