Iron
Iron is an important component of many enzymes and is essential for synthesis of hemoglobin. Iron is low in grains and thereby commonly supplemented from inorganic sources in a trace mineral premix. Newly born piglets develop iron deficiency in the first week of life and have to be provided with injectable iron.
Injectable iron
Piglets develop iron deficiency in the first week of life due to limited iron storages at birth, low levels of iron in sow milk, and the rapid growth rate that occurs during this early stage of life. Iron deficiency is characterized by anemia, and anemic piglets evidence low growth rate, lethargy, pale skin, and rough hair coats. Iron in excess is also prejudicial, as iron affects gut health, stimulates proliferation of bacteria, and causes diarrhea (Li et al., 2016).
Hemoglobin and hematocrit are commonly used as reliable blood criteria to indicate iron status in pigs. Hemoglobin levels of 11 g/dL or above indicate adequate blood iron status, levels of 9 to 11 g/dL indicate borderline anemia, and levels of 9 g/dL or below indicate an anemic condition (Bhattarai and Nielsen, 2015). For hematocrit, values above 30% indicate adequate blood iron status (Perri et al., 2016).
Iron injection in piglets is a well-stablished practice to prevent iron deficiency and anemia. The injection is administered intramuscularly and preferentially in the neck area of piglets. The most commonly used sources of iron are iron dextran and gleptoferron, which have shown similar efficacy in preventing iron deficiency in piglets (Morales et al., 2018). However, absorption of iron seems to be greater with gleptoferron due to its potentially greater iron bioavailability (Morales et al., 2018).
A dose of 200 mg of injectable iron is required to maximize growth performance and improve blood iron status at weaning and in the nursery (Williams et al., 2018a). The need for a second iron injection depends on the amount of iron given in the first injection. When using an injection of 200 mg of iron within 2 days of birth, an additional booster dose of 100 mg of iron midway through lactation can improve blood iron status, but it does not provide further benefits in growth performance (Williams et al., 2018a).
An iron injection is typically applied within the first week after birth. The optimum timing for iron injection is around 4 or 6 days after birth, when it seems to maximize growth performance and improve blood iron status at weaning and in the nursery (Williams et al., 2018b). On the other hand, providing an iron injection too soon (day 2) or too late (days 8 or 10) after birth seems to restrict pig performance (Williams et al., 2018b).