Iron Transporters Are Differentially Regulated by Dietary Iron, and Modifications Are Associated with Changes in Manganese Metabolism in Young Pigs1–3

Abstract

To investigate the effects of dietary iron (Fe) on manganese (Mn) metabolism, 24 weaned pigs (21 d old) were blocked by litter and weight and randomly assigned to the following treatments: 1) no supplemental Fe [low Fe (L-Fe)]; 2) 100 mg supplemental Fe/kg [adequate Fe (A-Fe)]; and 3) 500 mg supplemental Fe/kg [high Fe (H-Fe)]. The basal diet was analyzed to contain 20 mg Fe/kg. Tissues were harvested after 32 d of feeding. Daily gain (least square means ± SEM) was greater in A-Fe pigs (328.3 ± 29.9 g/d) than in L-Fe pigs (224.0 ± 11.2 g/d). Hemoglobin concentrations on d 32 were lower in L-Fe pigs (62 ± 3.5 g/L) than in A-Fe pigs (128 ± 5.6 g/L) and did not differ between pigs fed A-Fe and H-Fe (133 ± 12.0 g/L). Liver Fe increased with increasing dietary Fe. Relative hepatic hepcidin expression was greater in pigs fed A-Fe and H-Fe than in those fed L-Fe. Relative expressions of duodenal divalent metal transporter 1 (DMT1) and solute carrier family 39 member 14 (ZIP14) were increased in L-Fe pigs compared with H-Fe pigs. Liver copper (Cu) was higher in L-Fe (0.56 ± 0.04 mmol/kg) and H-Fe (0.58 ± 0.04 mmol/kg) pigs than in A-Fe pigs (0.40 ± 0.04 mmol/kg). Liver Mn was lower in H-Fe pigs (0.15 ± 0.01 mmol/kg) than in A-Fe (0.23 ± 0.02 mmol/kg) or L-Fe pigs (0.20 ± 0.02 mmol/kg). Duodenal Mn concentrations were greater in L-Fe pigs than in A-Fe or H-Fe pigs. Fe deficiency in pigs increased gene expression of duodenal metal transporters (DMT1 and ZIP14) and supplementation with H-Fe reduced expression of DMT1 and ZIP14, which may have decreased absorption of Mn.