Effects of natural oral alternatives to parental iron supplementation on haematological and health-related blood parameters of organic piglets

The most common and efficient iron supply to prevent neonatal anaemia in piglets is the injection of iron dextran or gleptoferron. This treatment is problematic in organic farms because organic specifications strictly limit the use of chemically synthesised allopathic drugs. Based on the observation that piglets raised outdoors rarely develop anaemia, we hypothesised that piglets satisfy their iron needs by ingesting soil from their environment. Therefore, we compared the efficacy of a 100-mg intramuscular iron dextran injection (Iron, 8 litters, n = 98 piglets) at 4 days (d) of age (d4), to a daily ad libitum supply of dried soil (Soil, 8 litters, n = 101) or dried peat-like river silt (Peat, 8 litters, n = 102) from d4 to weaning (at 49 days of age, d49). Pigs were raised according to organic farming rules. Blood was collected on three males and three females per litter on d4, 20, 41, 50 and 69. BW was similar in the three groups on d4, 20, 41, 50 and 69 (P > 0.1). During the experiment, piglets were affected by a severe digestive E. coli episode but litter mortality rate between d4 and d69 did not differ between groups (P > 0.1). Blood haemoglobin concentration (Hb) was similar in all groups on d4, 50 and 69. However, on d20, Hb was higher in Peat and Iron groups than in the Soil group (P < 0.001), and on d41 and d50, Hb was higher in the Peat group than in Iron and Soil groups (P < 0.001). Mean red blood cell volume (RBCV) remained stable over time in the Peat group. In comparison, RBCV dropped in the Soil group on d20 and d41 (P < 0.001), and in the Iron group on d41 (P < 0.001). Soil and Iron group RBCV returned values similar to the Peat group by d69 (P > 0.1). In conclusion, soil supply in the pen was not sufficient to ensure a satisfactory iron intake in piglets, unlike peat-like river silt, which enable to reach haemoglobin concentrations above 80 mg/mL for over 90% of the piglets from d20 and, over 100% of piglets at weaning. The daily supply of the silt proved more efficient than the 100-mg iron injection beyond 20 days.