Abstract A total of 143 newborn piglets from 15 litters (7 litters from PIC337 and 8 from PIC800 sire lines, all bred to Camborough sows) were allotted to 6 treatments in a 2 × 3 factorial arrangement. Main factors were: 1) sire line (PIC337 vs. PIC800), and 2) number of iron injections (0, 1, or 2 intramuscular injections of 200 mg iron; UNIFERON®200, Pharmacosmos, Inc.) administered at d 3 (1 injection), or d 3 and 8 (2 injections). Colostrum and milk (d 15 of lactation) were collected. Six piglets per sire line at birth and six per treatment at weaning (d 18.9 ± 1.6 of age) were euthanized for collection of liver, spleen, kidney, heart, whole blood and remaining body tissue for iron analysis. Remaining pigs were transferred to a nursery facility and fed a common diet for 28 d. Body weight in suckling and nursery period and feed disappearance in nursery period were measured to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio. Hemoglobin levels were measured at d 3, 8, 15 of age, at weaning, and weekly in the nursery period. Plasma malondialdehyde, catalase, and superoxide dismutase levels were measured at d 0, 14 and 28 postweaning. PIC337 pigs had greater overall ADFI in the nursery period (P = 0.10, tendency; 0.54 and 0.49 kg/d for PIC337 and PIC800, respectively) and had a greater body weight at d 28 postweaning (P = 0.06, tendency; 15.48 and 13.99 kg, respectively) than PIC800 pigs. PIC337 pigs had lower hemoglobin levels than PIC800 pigs from d 15 of age to d 7 postweaning (P 0.05; 101.7 and 108.5 g/L respectively). Increasing iron injection frequency linearly increased weaning weight (P 0.05; 4.99, 5.30, and 5.50 kg, respectively), body weight (P 0.05, tendency; 13.4, 15.2, and 15.6 kg, respectively) and ADG through d 28 postweaning (P 0.05; 0.295, 0.353, and 0.362 kg/d, respectively). Hemoglobin levels also increased linearly and quadratically from d 15 of age to d 14 postweaning (P ≤ 0.05; 72.5, 108.9, and 114.2 g/L at d 14 postweaning, respectively). Plasma malondialdehyde levels increased quadratically at weaning (P = 0.06) and d 14 postweaning (P 0.05; 13.8, 16.2, 15.6 µM, respectively), with a peak in the 1-injection group. Plasma catalase level increased linearly at d 14 postweaning (P ≤ 0.05). Total iron retention in individual organs and whole-body (P 0.05; 121.3, 291.5, and 509.1 mg, respectively) increased linearly with iron injection frequency. No differences were observed between sire lines in the whole-body iron retention at birth at weaning, and in iron content of colostrum and milk. In conclusion, a second iron injection before weaning increased hemoglobin levels through d 14 postweaning, nursery weight gain, antioxidant status and whole-body iron retention, confirming that most of the injected iron was retained in the body.
Torres et al. (Wed,) studied this question.