Longitudinal Effects of Iron Deficiency Anemia and Subsequent Repletion on Blood Parameters and the Rate and Composition of Growth in Pigs

Iron deficiency is reported as the most common nutrient deficiency worldwide. Due to rapid growth, infants are at particular risk for developing iron deficiency, which can easily progress to iron deficiency anemia (IDA), if not treated. The aim of this study was to determine the lasting effects of an early-life iron deficiency after a period of dietary iron repletion. Forty-two intact male pigs were fed, ad libitum, either control (CONT, 21.3 mg Fe/L) or iron-deficient (ID 2.72 mg Fe/L) milk replacer from postnatal day (PND) 2 to 32 (phase 1). From PND 33 to 61 (phase 2), all pigs were transitioned onto a series of industry-standard, iron-adequate diets. Blood was collected weekly from PND 7 to 28, and again on PND 35 and 56, and tissues were collected at either PND 32 or PND 61. At the end of phase 1, ID pigs exhibited reduced hematocrit (Hct; p < 0.0001) and hemoglobin (Hb; p < 0.0001) compared with CONT pigs, but neither Hct (p = 0.5968) nor Hb (p = 0.6291) differed between treatment groups after dietary iron repletion at the end of phase 2. Body weight gain was reduced (p < 0.0001) 58% at PND 32 in ID pigs compared with CONT pigs during phase 1, and this effect remained significant at the end of phase 2 (p = 0.0001), with ID pigs weighing 34% less than CONT pigs at PND 61. Analysis of peripheral protein and messenger RNA (mRNA) gene expression biomarkers yielded inconclusive results, as would be expected based on previous biomarker analyses across multiple species. These findings suggest that early-life iron status negatively influences blood parameters and growth performance, with dietary iron repletion allowing for full recovery of hematological outcomes, but not growth performance.