Additional intramuscular iron injections tended to improve post-weaning growth when administered at weaning, but not at day seven of life

Piglets have a high requirement for iron due to their rapid growth rates and low body iron stores; moreover, intensive production conditions restrict access to environmental sources of iron, such as soil. The low iron content of sow colostrum and milk, combined with the partitioning of limited nutrients among many piglets in a litter, results in inadequate piglet iron intake, predisposing them to iron-deficient anemia (IDA) during lactation and weaning. Prevalent IDA results in reduced post-weaning growth and reduced hemoglobin (Hb) concentrations. To combat this, indoor-reared piglets are given an injectable iron supplement shortly after birth to maintain body iron stores until weaning, when feed containing dietary iron is consumed. Due to continued selection for growth rates and litter sizes, this single injection is now considered inadequate to meet iron requirements. It was hypothesized that an additional iron injection, irrespective of timing, would improve Hb concentrations and growth performance, with a day 7 injection resulting in higher Hb and growth at weaning and a weaning injection increasing Hb and performance in pigs later in the nursery period. A total of 440 mixed sex pigs were used in this experiment in three treatment groups: control: only receiving iron dextran two days after birth; day 7: receiving iron injections at days two and seven after birth; Weaning iron: receiving iron dextran injections on day two and at weaning (20.1 days). Hb concentrations were significantly (<i>P </i>< 0.001) improved in the day 7 treatment for 18 days after weaning. Pigs in the control and weaning iron groups had a treatment mean of 9.9 g/dL ± 0.32 and 9.7 g/dL ± 0.32, respectively, indicating sub-clinical anemia, compared to the day 7 group with a treatment mean of 12.2 g/dL ± 0.32, indicating healthy Hb concentrations. Average daily gain tended (<i>P</i> = 0.08) to be higher in the weaning iron treatment group during the second week of the experiment compared to the control and day 7 groups. Pig removals were also significantly (<i>P</i> < 0.001) reduced in the weaning treatment group. Plasma hepcidin anti-microbial peptide, was elevated in the weaning iron group after injection, possibly impairing enteric iron absorption. An additional injection at weaning showed potential for improved growth in the post-weaning period and has practical advantages for producers.