Addition of tert-butylhydroquinone (TBHQ) to maize oil reduces lipid oxidation but does not prevent reductions in serum vitamin E in nursery pigs

Authors: HUNG, YANG - University Of Minnesota; HANSON, ANDREA - University Of Minnesota; URRIOLA, PEDRO - University Of Minnesota; JOHNSTON, LEE - University Of Minnesota; Kerr, Brian; SHURSON, GERALD - University Of Minnesota

Submitted to: Journal of Animal Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/2019
Publication Date: 7/4/2019
Citation: Hung, Y.T., Hanson, A.R., Urriola, P.E., Johnston, L.J., Kerr, B.J., Shurson, G.C. 2019. Addition of tert-butylhydroquinone (TBHQ) to maize oil reduces lipid oxidation but does not prevent reductions in serum vitamin E in nursery pigs. Journal of Animal Science and Biotechnology. 10:51. https://doi.org/10.1186/s40104-019-0362-5.
DOI: https://doi.org/10.1186/s40104-019-0362-5

Interpretive Summary: Corn oil is an abundant source of vegetable oil used in human foods and animal feeds. In animal feeds, the addition of corn oil not only increases energy density, but also enhances the absorption of fat-soluble vitamins and improves feed efficiency and palatability. However, corn oil contains high concentrations of unsaturated fatty acids making it susceptible to peroxidation when storage and processing conditions involve exposure to oxygen, heat, and pro-oxidant metals. Even though corn oil contains significant amounts of natural antioxidants, synthetic antioxidants are considered to be more effective to prevent peroxidation during oil processing, with tert-butylhydroquinone (TBHQ) having a superior antioxidant capacity due to its stability at high temperatures. The current experiment was conducted to determine if TBHQ addition to previously peroxidized corn oil would prevent further lipid peroxidation and ameliorate the potential negative effects on growth performance in nursery pigs. Data from this experiment indicate that heating corn oil to 180°C for 12 hours resulted in increased indices of peroxidation in corn oil, but that feeding this moderately peroxidized corn oil had no impact on pig performance. In addition, supplementation of TBHQ to the peroxidized corn oil reduced additional peroxidation thereby enhancing its stability, but its addition did not have an effect on pig growth performance. This information is important for nutritionists at universities, feed companies, and pork production facilities indicating that a corn oil can be peroxidized due to heating, but depending upon its level of peroxidation, it may not have an effect on animal performance. Likewise, the data shows that synthetic antioxidants can prevent further lipid peroxidation, but may not affect pig performance when peroxidized oil is fed. Taken together, these factors are important in evaluating the use of peroxidized oils and synthetic antioxidants in feed production.

Technical Abstract: The abundance of maize oil being produced and used in human foods and animal feeds, along with its high susceptibility to peroxidation, requires evaluating the effectiveness of commercially available antioxidants in swine diets containing peroxidized maize oil. Therefore, the current study was designed to evaluate growth performance of nursery pigs fed peroxidized maize oil and to determine if there was any amelioration by using antioxidants in a 2 × 2 factorial design. Two hundred eight (208) weaned pigs (body weight (BW) = 7.6 ± 0.6 kg) were blocked by initial BW into 13 blocks, resulting in 4 pigs per pen and 13 pens per treatment. Dietary treatments included 6% unperoxidized or peroxidized maize oil, and 0 or 60 mg/kg of tert-butylhydroquinone (TBHQ), which was added after lipid peroxidation. Peroxidized maize oil was prepared by heating at 185°C with 12 L/min of air for 12 h, which resulted in achieving a peroxide value (PV) of 5.98 mEq O2/kg and TBARS of 0.11 mg malondialdehyde (MDA) eq/g. Data for average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were collected from 5 time periods of a 2-phase feeding program (Phase 1 = d 0 to 12 and Phase 2 = d 13 to 34). Serum and liver samples were collected from 1 pig per pen, which had BW closest to average initial BW to determine oxidative status on d 34. Addition of TBHQ to diets containing peroxidized maize oil decreased PV by 37% and increased the oil stability index by 69%. Final BW of pigs was not affected by consuming peroxidized maize oil with or without TBHQ supplementation. Similarly, ADG, ADFI, and G:F were not different among the four dietary treatments. However, pigs fed peroxidized maize oil tended (P < 0.08) to increase hepatosomatic index by 5% compared with those fed unperoxidized oil, and this was not affected by adding TBHQ. The serum vitamin E concentration of pigs fed peroxidized maize oil was less (P < 0.03) than pigs fed unperoxidized oil, but this reduction was not reversed by adding TBHQ. Finally, there were no differences in selenium concentration in the serum and liver from feeding diets containing unperoxidized or peroxidized maize oil with or without supplementation with TBHQ. In conclusion, addition of TBHQ did not affect growth performance and vitamin E status in pigs fed moderately peroxidized maize oil, but TBHQ reduced lipid peroxidation, enhanced the oil stability, and appeared to reduce oxidative stress.