Supplemental dietary inulin influences expression of iron and inflammation related genes in young pigs.

We have previously shown improved hemoglobin (Hb) repletion efficiency by supplementing a 50:50 mixture of short (P95) and long-chain (HP) inulin (Synergy 1, BENEO-Orafti) into a corn-soybean meal-basal diet (BD) for young pigs. In this study, weanling pigs (5 or 6 wk old) were fed the BD or the BD + 4% of P95, HP, or Synergy 1 (50:50 mixtures of HP and P95) for 5-7 wk. Blood Hb concentrations of pigs were measured weekly and digesta samples were collected at the end of the trial. In a replicate experiment, total RNA was isolated from the liver and mucosa of duodenum, ileum, cecum, and colon of all pigs at the end of the trial. Relative mRNA expression of 27 genes, including iron and inflammation-related genes, was quantified using real-time quantitative-PCR. Although all 3 types of inulin resulted in similar improvements (P < 0.05) in blood Hb concentration and liver ferritin protein amount, neither type of inulin was detectable in the digesta of cecum or colon. Supplemental inulin enhanced the expression of iron-storing protein genes but decreased that of inflammation-related genes. Such effects were more pronounced (P < 0.05) in the mucosa of the lower than the upper gut and were seen on 7 genes in liver. In conclusion, all 3 types of inulin shared similar efficacy and possibly similar modes of action in improving dietary iron utilization by young pigs. Suppressing inflammation-induced genes that can negatively influence iron metabolism might help explain the benefit of inulin.