Effects of circadian iron administration on iron bioavailability and biological rhythm in pigs

BACKGROUND Iron supplements are limited by their poor absorption and low efficacy. A circadian feeding schedule would affect the circadian rhythm and improve nutrient metabolism. In this study, 18 iron‐deficient piglets were randomly assigned to three groups: a control group receiving a constant diet with mid‐iron (MI), a ‘HL’ group receiving a high‐iron (HI) diet at 8:00 h and a low‐iron (LI) diet at 18:00, and an ‘LH’ group receiving a LI diet at 8:00 and a HI diet at 18:00. The effects of circadian iron administration on iron absorption, iron status, and biological rhythm in iron‐deficient piglets were investigated. RESULTS Serum iron and hemoglobin improved significantly ( P < 0.05) but did not significantly differ in the circadian iron‐feeding groups ( P > 0.05). Iron concentration in the liver and spleen was significantly higher in the LH group than in the HL group ( P < 0.05), and mRNA expression of divalent metal transport 1 (DMT1), cytochrome B (CYBRD1) and ferroportin (FPN) genes in the duodenum was significantly elevated in the LH group ( P < 0.05). The clock‐related genes showed differential expression in the duodenum, with greater mRNA expression for period (Per2) and cryptochrome (Cry1 and Cry2) in the LH group ( P < 0.05). CONCLUSION Circadian iron administration affected iron absorption and iron storage in pigs. Iron supplementation in the evening might be a more effective pattern for iron utilization. The rhythmic system in the intestine, driven by the time, played an important role in this process. © 2020 Society of Chemical Industry