Feeding nursery pigs diets containing peroxidized soybean oil has minimal effects on oxidative status but dramatically reduces serum vitamin E concentrations.

A subgroup of pigs from two experiments (EXP) were selected to evaluate the impact of pigs fed diets containing peroxidized soybean oil (SO) on plasma-based measures of oxidative stress and vitamin E. Pigs were fed diets containing SO that was either unprocessed (23 °C; peroxide value of 3 meq/kg and an anisidine value of 4) or thermally processed at 135 °C for 42 h (peroxide value of 30 meq/kg and an anisidine value of 501). The corn-soybean meal-based diets contained either 10% SO (EXP 1) or 8% SO (EXP 2). Pigs were fed the experimental diets for 22 d (EXP 1, 13.5 to 24.0 kg, 2 pigs/pen) or 27 d (EXP 2, 21.3 to 37.5 kg, 1 pig/pen), each with 10 replications per dietary treatment. Pigs fed diets containing the peroxidized SO had reduced ADG, ADFI, and GF compared to pigs fed diets containing the unheated SO (P ≤ 0.01). Pigs fed diets containing peroxidized SO had increased plasma concentrations of F2-isoprostanes and reactive oxygen metabolites compared to pigs fed diets containing unheated SO (P ≤ 0.01). In contrast, plasma thiobarbituric acid reactive substances concentrations tended to decrease in pigs fed diets containing peroxidized SO compared to pigs fed diets containing unheated SO (P = 0.10). There was no apparent effect of pigs consuming diets containing peroxidized SO on plasma antioxidant adsorbent capacity or an oxidative stress index (P ≥ 0.19). Pigs fed diets containing peroxidized SO resulted in a reduction in plasma vitamin E compared to pigs fed diets containing unheated SO (P ≤ 0.01). Results indicate that adding SO that has been thermally processed thereby containing high concentrations of aldehydes resulted in inconsistent changes of markers of oxidative stress, but dramatically reduced plasma vitamin E concentrations.