Abstract Piglets are born with limited iron reserves and experience a physiological decline in hemoglobin (Hb) due to rapid postnatal growth and low iron content of sow’s milk. To prevent iron deficiency anemia, intramuscular (IM) iron injection is routinely administered within the first days postpartum. However, parenteral supplementation may increase infection risk, induce stress and require substantial labour. An alternative strategy is the automatic delivery of iron through a milk cup system, allowing piglets to self-regulate intake while reducing handling stress and labour demands. This study evaluated the effects of iron supplementation via complementary milk versus IM injection during lactation on post-weaning growth and hematological parameters. A total of 1,241 DanBred × Pietrain piglets received complementary milk (Pump’n’Grow, AB Neo, Spain). Half received an IM iron injection (INJ; 200 mg gleptoferron with 45 mg toltrazuril) one day after birth, while others received a liquid iron supplement (PB; Piglet Boozt, AB Neo, Spain) containing FeSO4, vitamin B12, zinc, organic acids, and salts, administered through the milk for 18 days (1,300 mg FeSO4/L milk). Piglets were weaned at 24 days of age (initial body weight (BW)= 6.63 ± 0.20 kg) and assigned to 48 pens (22–23 pigs/pen) according to sex, body weight, and prior iron treatment. All pigs were fed standard post-weaning diets containing 100 ppm Fe (days 0–14) and 80 ppm Fe (days 14–43). Forty-eight pigs were sampled two days pre-weaning and at days 13 and 41 post-weaning for analysis of hematocrit (Ht), Hb, and red blood cell (RBC) counts. Piglets supplemented with PB during lactation showed higher feed intake and growth during days 0–14, 14–28, and overall (0–43) post-weaning (p 0.05), resulting in greater BW (day 43: INJ = 18.31 kg; PB = 19.27 kg; p 0.001). The PB group also showed lower culling (INJ = 0.74%; PB = 0.17%; p = 0.026) and combined mortality plus culling rates (INJ = 1.25%; PB = 0.35%; p = 0.049) between days 28–43 and tended to have fewer diarrhoea days during the first two weeks post-weaning (INJ = 0.37; PB = 0.21; p = 0.059). Although PB piglets had lower pre-weaning Ht and Hb levels (p = 0.002), Ht values equalized by day 13, and PB pigs showed higher RBC counts (INJ = 5.7 × 106; PB = 6.6 × 106; p = 0.004). By day 41, hematological parameters were similar between treatments. In conclusion, liquid iron supplementation through a milk dosing system during lactation improved post-weaning growth performance and reduced mortality and culling in the late nursery phase. Although pre-weaning Ht and Hb were initially lower, these differences resolved after weaning.
Sobrevia et al. (2026) studied this question.