Longitudinal effects of early-life iron status in pigs
Iron deficiency is reported as the most common nutrient deficiency worldwide. Due to rapid growth and low iron stores at birth, infants are at particular risk for developing iron deficiency. Further, iron deficiency is known to affect the developing microbiota. Thus, the aim of this study was to determine the lasting effects of an early-life iron deficiency on physiological outcomes after a period of iron repletion in the diet. Forty-two intact male pigs were provided ad libitum access to dietary treatments including control (CONT, 21.3 mg Fe/L) or iron-deficient (ID, 2.72 mg Fe/L) milk replacers from postnatal day (PND) 2 to 32. From PND 33 to 61, all pigs were transitioned through a series of age-appropriate, iron-adequate diets. Blood was collected weekly from PND 7 to 28, and again on PND 35 and 56, and fecal samples and tissues were collected at PND 32 and/or 61. Body weight gain was reduced (P < 0.001) in ID pigs compared with CONT pigs before PND 32, with treatment effects remaining (P = 0.03) after dietary iron repletion. At PND 32, ID pigs exhibited reduced (P < 0.001) hematocrit and hemoglobin compared with CONT pigs, but both responses had equalized after iron repletion. Analysis of peripheral protein and mRNA gene expression biomarkers yielded inconclusive results as would be expected based on previous biomarker analyses across multiple species. Additionally, ID pigs exhibited increased (P < 0.001) total volatile fatty acid (VFA) concentrations in ascending colon and rectal contents compared with CONT pigs at PND 32, but differences in VFA concentrations were absent after iron repletion. In ascending colon contents, 15 genera differed between ID and CONT pigs, while 27 genera were differentially affected in rectal contents. Finally, ID pigs had higher (P = 0.012) relative abundance of Lactobacillus and lower (P = 0.042) relative abundance of Parabacteroides in ascending colon contents compared with CONT pigs. In rectal contents, ID pigs had lower (P ≤ 0.05) relative abundances of Bacteroides, and various members of the Clostridium family including Clostridiaceae, Lachnospiraceae, and Ruminococcaceae. These findings suggest that early-life iron status causes profound shifts in growth performance and hematological outcomes, with only partial recovery following dietary iron repletion. Interestingly, VFA concentrations were increased in ID pigs, and microbial composition was shifted within the colon, though stabilization of VFA after receiving a common, iron-replete diet was observed.
iron deficiency, iron deficiency anemia, pig, iron repletion, pediatric nutrition, comparative nutrition, volatile fatty acids, microbiota
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign