Sow Anemia and Piglet Iron Supplementation: Impacts on Farrowing and Weaning Performance

Abstract Anaemia in sows, defined by low haemoglobin (HGB), haematocrit (HCT), or red blood cell (RBC) counts, may prolong farrowing and increase stillbirth risk and maternal stress. In piglets, anaemia is also common, and routine iron supplementation is aimed at preventing its occurrence; however, a second injection may offer additional benefits. This study investigated the effects of maternal anaemia on sow and piglet health, farrowing performance, and litter outcomes, as well as the impact of one versus two iron injections on piglet haematological status. Forty-nine sows and their litters were enrolled one week before farrowing and classified as anaemic (HGB 10.4 g/dL; A, n = 20) or non-anaemic (HGB ≥ 10.4 g/dL; NA, n = 29) based on haematological reference values. Within each litter, piglets were divided into 2 groups, based on their body weight (BW), to receive either one iron injection (F1: 200 mg dextran iron on day 3) or two injections (F2: 200 mg dextran iron on days 3 and day 15). Blood samples were collected from sows near farrowing, while piglet BW and mortality were recorded at days 0, 3, 15, and 28 (waening). Piglet blood samples were collected at weaning. Sow blood data were analysed using a linear model including group, parity, and batch as fixed factors. Piglet haematological data were evaluated using a linear mixed-effects model including sow group, parity, batch, and number of iron injections as fixed factors and sow as a random effect. Cumulative piglet mortality was analysed using a binomial mixed-effects model including sow group, parity, batch, litter size at weighing, and mortality up to day 15 (for the day 28 model) as fixed factors and sow as a random effect. Anaemic sows exhibited significantly lower RBC, HGB, and HCT (p 0.001), and higher mean corpuscular volume (MCV) and platelet count (PLT) (p = 0.03 and p = 0.05, respectively), confirming impaired erythropoiesis. Piglets of F2 group from anaemic sows showed lower cumulative mortality at 28 days of life (p 0.001), while no difference was observed for growth performance. Two injections improved neutrophil (NEUT), eosinophil (EO), HGB, and HCT values (p 0.05). Conversely, red cell distribution width (RDW-CV) was higher in F1 piglets (p 0.05), suggesting less stable erythrocyte production. In conclusion, maternal anaemia near farrowing primarily impairs erythrocyte parameters in sows, indicating altered haematological homeostasis, while did not affect piglets ones. Providing piglets with a second iron injection enhances piglet haematological profile and their survival when born from anaemic sows. These findings highlight the importance of monitoring sow iron status during gestation and support the inclusion of a second postnatal iron supplementation to improve piglet health and reduce mortality in herds affected by maternal anaemia.