If the piglets are not supplemented with iron, they will develop iron deficiency (Hb < 110 g/L) or iron deficiency anemia (IDA) (Hb < 90 g/L) (Egeli et al., 1998; Bhattarai and Nielsen, 2015; Stojanac et al., 2016). The gene discussed is GSTM1; the disease is anemia.