Supplementing antioxidants to pigs fed diets high in oxidants: I. Effects on growth performance, liver function, and oxidative status1

Abstract

The objective of the study was to determine the effects of a dietary antioxidant blend (ethoxyquin and propyl gallate) and vitamin E on growth performance, liver function, and oxidative status in pigs fed diets high in oxidants. Crossbred barrows (n=100, 10.91±0.65 kg BW, 36±2 d of age, Landrace×Duroc) were allotted to 5 treatments on the basis of BW (5 replicate pens per treatment, 4 pigs per pen). Treatments included 1) HO, high-oxidant diet containing 5% oxidized soybean oil and 10% PUFA source (providing 2.05% docosahexaenoic acid in the diet), 2) VE, the HO diet with 11 IU/kg of added vitamin E, 3) AOX, the HO diet with antioxidant blend (135 mg/kg), 4) VE+AOX, the HO diet with both vitamin E and antioxidant blend, and 5) SC, a standard corn-soy control diet. The trial lasted for 118 d; on d 83, the HO diet pigs were switched to the SC diet because the animals were displaying very poor health. Compared with SC pigs, HO pigs had decreased ADG (0.92 vs. 0.51 kg for d 26 to 55, 1.29 vs. 0.34 kg for d 56 to 82; P<0.05) and ADFI (1.84 vs. 0.96 kg for d 26 to 55, 3.41 vs. 1.14 kg for d 56 to 82; P<0.05). However, switching the HO pigs to the SC diet resulted in HO pigs having a greater ADG than VE-fed pigs from d 83 to 118 (0.90 vs. 0.60 kg; P<0.05). The antioxidant blend restored pig performance to a level similar that of pigs fed the SC diet (P>0.05) with greater G:F for the entire period (0.44 vs. 0.38; P<0.05). A greater liver to BW ratio was found in HO compared with other treatments on d 55 and in VE on d 118. Total bilirubin concentration in plasma of HO pigs on d 55 was greater than that in VE+AOX pigs (P<0.05), whereas on d 118, bilirubin concentration in VE was higher than those in VE+AOX and SC (P<0.05). A similar trend was observed in aspartate transaminase. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) and carbonyl were elevated (P<0.05) in the HO pigs compared with the SC pigs on d 55 but not on d 118. Liver TBARS and carbonyl concentrations showed a similar trend, except that HO pigs had the greatest carbonyl concentration on d 118. Pigs fed AOX diets had plasma and liver TBARS and carbonyl concentrations similar to those fed SC diets. In the oxidative stress model used in this study, dietary addition of antioxidant blend or antioxidant blend+vitaimin E was effective in improving growth, liver function, and plasma markers of oxidative stress, but VE alone was not.

Growth performance, oxidative stress and immune status of newly weaned pigs fed peroxidized lipids with or without supplemental vitamin E or polyphenols

“…On the other hand, there may be a threshold beyond which the impact of peroxidized lipids manifests itself. The fact that detrimental effects of dietary peroxidized soybean oil was expressed more in the long term is supported by Anjum et al [14] and Lu et al [30] in broilers and pigs, respectively. DeRouchey et al [36], Liu et al [11] and Rosero et al [12] reported reductions in ADFI in pigs when feeding peroxidized lipids and these effects were dose-dependent.…”

“…In the present study, protein carbonyl in serum was increased by lipid peroxidation, particularly on day 35, but supplementation with antioxidants did not ameliorate this effect. Likewise, Lindblom et al [21] and Lu et al [30] reported increased protein carbonyl in serum of pigs fed peroxidized oil. Boler et al [9] did not observe differences in protein carbonyls in plasma when using a synthetic antioxidant blend supplemented to diets containing peroxidized corn oil, when compared with a peroxidized corn oil diet without antioxidant in pigs.…”

“…Boler et al [9] did not observe differences in protein carbonyls in plasma when using a synthetic antioxidant blend supplemented to diets containing peroxidized corn oil, when compared with a peroxidized corn oil diet without antioxidant in pigs. A study conducted by Lu et al [30] showed significant decreases in plasma carbonyls on day 55 in growing pigs fed peroxidized lipids when using dietary vitamin E in combination with a synthetic antioxidant blend, but this was not the case on day 118, indicating that long-term supplementation of peroxidized oil may overwhelm the antioxidant system resulting in increased markers of oxidative stress.…”

“…Rooke et al [44] reported that an antioxidant blend or antioxidant blend plus vitamin E improved growth performance when feeding 5% of dietary peroxidized oil and showed regeneration of vitamin E by vitamin C and glutathione peroxidase. Peroxidation products could reduce the function of fat-soluble vitamins [30].…”

“…Several studies reported positive effects of vitamin E or plant polyphenols on meat oxidation in broilers [26,27], meat quality in finishing pigs [9], and antioxidant activity in piglets [28,29]. Moreover, the supplementation of vitamin E plus synthetic antioxidant blends or synthetic antioxidants to diets containing peroxidized vegetable oil for weaned piglets and finishing pigs improved growth and reduced lipid and protein oxidation [9,30].…”