Effect of Secondary Iron Injection Timing to Suckling Pigs on Pre- and Post-Weaning Growth Performance and Hematological Parameters

Abstract The objective of this study was to evaluate the effects of secondary iron injection timing to suckling pigs on pre- and post-weaning growth performance and hematological variables. A total of 22 pigs (initial body weight: 1.62 ± 0.12 kg) from 4 litters were allotted into 3 treatments within litter based on body weight and sex at d 1-3 of age (d 0 of experiment) as follows: 1) Control: intramuscular injection of 150 mg iron-dextran at d 0 of experiment only, 2) Iron14: intramuscular injection of 150 mg iron-dextran at d 0 of experiment and 100 mg iron-dextran at d 10 of experiment (14 d before weaning), and 3) Iron7: intramuscular injection of 150 mg iron-dextran at d 0 of experiment and 100 mg iron-dextran at d 17 of experiment (7 d before weaning). The pigs were housed by litter in the suckling and nursery periods with a common corn-soybean meal-based diet during the nursery period. Body weight, hemoglobin concentrations and hematocrit were measured at d 0, 10, 17, 24 (weaning), 31 and 38 of experiment. The Iron14 treatment tended to have greater final weight at d 38 of experiment than the control treatment (P = 0.07; 10.97 vs. 9.38 kg) and the Iron7 treatment had intermediate value (10.15 kg). The ADG in d 24-31 postweaning tended to be greater in the Iron14 treatment than the control and Iron7 treatments (P = 0.08; 82.6, 151.8, and 53.5 g/d for the control, Iron14, and Iron7 treatments, respectively). In hemoglobin concentrations, the Iron14 treatment had greater levels than the control treatment at d 17 (P = 0.06; 12.24, 13.51, and 11.66 g/dL, respectively), 24, and 31 (P < 0.05; 10.72, 12.74, and 12.77 g/dL, respectively) of experiment whereas the Iron7 treatment had greater concentrations than the control treatment at d 24, 31, and 38 (P< 0.05; 9.46, 10.60, and 11.21 g/dL, respectively) of experiment and less than Iron14 treatment at d 17 and 24 (P < 0.05; 10.63, 12.95, 11.91 g/dL, respectively) of experiment. Hematocrit showed similar response to hemoglobin concentrations in which the Iron 14 treatment had greater hematocrit than the control treatment at d 17, 24, 31 (P < 0.05) and 38 (P = 0.10) of experiment while the Iron7 treatment had greater hematocrit levels than the control treatment at d 24, 31, and 38 (P < 0.05) of experiment. Hematocrit levels only at d 17 of experiment was greater in the Iron14 treatment than the Iron7 treatment (P < 0.05). In conclusion, the secondary iron injection to suckling piglets could improve early postweaning growth when the pigs were injected with iron at 14 d before weaning and increase hemoglobin concentrations and hematocrit regardless of timing, but the differences in hemoglobin and hematocrit values varied depending on the timing of secondary iron injection.