Dietary peroxidized maize oil affects the growth performance and antioxidant status of nursery pigs

This experiment was conducted to evaluate the effects of increasing dietary levels of peroxidized maize oil on growth performance and antioxidant status of nursery pigs. Weanling barrows (n = 128; initial body weight (BW) = 6.3 ± 1.4 kg) were blocked by initial BW and assigned randomly to 1 of 32 pens. Within block, pens were assigned randomly to 1 of 4 dietary treatments: 90 g/kg unheated maize oil, 60 g/kg unheated maize oil +30 g/kg rapidly peroxidized (RO) maize oil, 30 g/kg unheated maize oil +60 g/kg RO maize oil, or 90 g/kg RO maize oil. Diets were formulated to contain identical levels of total maize oil and standardized ileal digestible Lys to metabolizable energy (ME) ratios. Maize oil was heated for 12 h at 185 °C (air flow rate = 12 L/min) to yield RO (PV = 5.7 meq O₂/kg; thiobarbituric acid reactive substances = 26.7 mg malondialdehyde eq/kg) maize oil. A 3-phase feeding program (phase 1 = d 0-4, phase 2 = d 4-14, and phase 3 = d 14-35) was used, and average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and energetic efficiency (g ADG/MJ of ME intake) were determined. Serum was collected on d 0, 14, and 35 from 1 pig per pen that was subsequently harvested to obtain liver and heart tissue. Final BW (19.5 vs 18.5 ± 0.6 kg for 0 vs 90 g/kg RO maize oil; P < 0.15) and ADG (377.5 vs 347.0 ± 13.6 g for 0 vs 90 g/kg RO maize oil; P ≤ 0.10) tended to decline linearly with increasing dietary RO, but ADFI was not affected. Consequently, G:F (P < 0.05) declined linearly by 1.4-4% with increasing dietary concentrations of RO maize oil. The α-tocopherol content of serum declined with increasing dietary concentrations of RO maize oil (linear and cubic; P < 0.01). These data suggest that RO maize oil negatively affects growth performance and the efficiency of energy utilization of nursery pigs linearly and reduces serum α-tocopherol content.