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

Rice bran oil supplementation protects swine weanlings against diarrhea and lipopolysaccharide challenge

Early weaned piglets suffer from oxidative stress and enteral infection, which usually results in gut microbial dysbiosis, serve diarrhea, and even death. Rice bran oil (RBO), a polyphenol-enriched by-product of rice processing, has been shown to have antioxidant and anti-inflammatory properties both in vivo and in vitro. Here, we ascertained the proper RBO supplementation level, and subsequently determined its effects on lipopolysaccharide (LPS)-induced intestinal dysfunction in weaned piglets. A total of 168 piglets were randomly allocated into four groups of seven replicates (42 piglets each group, (21±1) d of age, body weight (7.60±0.04) kg, and half males and half females) and were given basal diet (Ctrl) or basal diet supplemented with 0.01% (mass fraction) RBO (RBO1), 0.02% RBO (RBO2), or 0.03% RBO (RBO3) for 21 d. Then, seven piglets from the Ctrl and the RBO were treated with LPS (100 μg/kg body weight (BW)) as LPS group and RBO+LPS group, respectively. Meanwhile, seven piglets from the Ctrl were treated with the saline vehicle (Ctrl group). Four hours later, all treated piglets were sacrificed for taking samples of plasma, jejunum tissues, and feces. The results showed that 0.02% was the optimal dose of dietary RBO supplementation based on diarrhea, average daily gain, and average daily feed intake indices in early weaning piglets. Furthermore, RBO protected piglets against LPS-induced jejunal epithelium damage, which was indicated by the increases in villus height, villus height/crypt depth ratio, and Claudin-1 levels, as well as a decreased level of jejunal epithelium apoptosis. RBO also improved the antioxidant ability of LPS-challenged piglets, which was indicated by the elevated concentrations of catalase and superoxide dismutase, and increased total antioxidant capacity, as well as the decreased concentrations of diamine oxidase and malondialdehyde in plasma. Meanwhile, RBO improved the immune function of LPS-challenged weaned piglets, which was indicated by elevated immunoglobulin A (IgA), IgM, β‍‍-defensin-1, and lysozyme levels in the plasma. In addition, RBO supplementation improved the LPS challenge-induced dysbiosis of gut microbiota. Particularly, the indices of antioxidant capacity, intestinal damage, and immunity were significantly associated with the RBO-regulated gut microbiota. These findings suggested that 0.02% RBO is a suitable dose to protect against LPS-induced intestinal damage, oxidative stress, and jejunal microbiota dysbiosis in early weaned piglets.

Developmental Changes of Immunity and Different Responses to Weaning Stress of Chinese Indigenous Piglets and Duroc Piglets during Suckling and Weaning Periods

To investigate developmental changes in immunity and different responses to weaning stress of piglets from different breeds during suckling and weaning periods, a total of 30 litters of Taoyuan black (TB) piglets, Xiangcun black (XB) piglets, and Duroc (DR) piglets (ten litters per breed) were selected at 1, 10, 21, and 24 days of age, respectively. The results showed that the liver index of TB piglets was higher at 10 days of age than that of the other days of age and breeds. Regardless of the days of age, TB and XB piglets had a higher plasma IgA level and lower ileal IgM level than in the DR piglets, and XB piglets had a lower plasma IgG level than the other breeds. TB and XB piglets had a higher IL-6 level and lower IL-17 level in plasma at 24 days of age than DR piglets, regardless of the days of age. The ileal levels of IL-2, IL-10, IFN-γ, and TNF-α were lower in the TB and XB piglets at 24 days of age than in the DR piglets. The ileal expression levels of IRAK1, CD14, MyD88, and NF-κB were down-regulated in the TB and XB piglets at 24 days of age compared to those in the DR piglets. These findings suggest that there were differences in the development of immune function among different pig breeds. Moreover, TB and XB piglets presented stronger resistance to weaning stress than the DR piglets, which may be related to the immune regulation mediated by the MyD88/NF-κB signaling pathway.

Taurine Attenuates Oxidized Fish Oil-Induced Oxidative Stress and Lipid Metabolism Disorder in Mice

The objective of this study was to determine the effect of dietary taurine on lipid metabolism and liver injury in mice fed a diet high in oxidized fish oil. The ICR mice (six weeks old) were randomly assigned to six groups and fed different diets for 10 weeks: control (CON), normal plus 15% fresh fish oil diet (FFO), normal plus 15% oxidized fish oil diet (OFO), or OFO plus 0.6% (TAU1), 0.9% (TAU2) or 1.2% (TAU3) taurine. Compared to the CON group, OFO mice showed increased liver index, aspartate aminotransferase (AST) and malondialdehyde (MDA) levels in serum (p < 0.05). In addition, OFO mice had increased cholesterol (CHOL)/high-density lipoprotein cholesterol (HDL-C) and decreased HDL-C/low-density lipoprotein cholesterol (LDL-C) and n-6/n-3 polyunsaturated fatty acid (PUFA) ratio in serum (p < 0.05) compared with CON mice. Notably, dietary taurine ameliorated the liver index and AST and MDA levels in serum and liver in a more dose-dependent manner than OFO mice. In addition, compared to OFO mice, decreased levels of CHOL and ratio of CHOL/HDL-C and n-6 PUFA/n-3 PUFA in serum were found in TAU3-fed mice. Supplementation with TAU2 and TAU3 increased the relative mRNA expression levels of peroxisome proliferator-activated receptor α, adipose triglyceride lipase, lipoprotein lipase, hormone-sensitive lipase and carnitine palmitoyl transferase 1 in liver compared with the OFO group (p < 0.05). Moreover, impaired autophagy flux was detected in mice fed with the OFO diet, and this was prevented by taurine. These findings suggested that dietary taurine might provide a potential therapeutic choice against oxidative stress and lipid metabolism disorder.

Early Weaning Affects Liver Antioxidant Function in Piglets

Simple Summary

Early weaning is used to improve efficiency in pig production. However, early weaning may trigger liver oxidative stress in piglets. In this study, we evaluated the effects of early weaning on the development and antioxidant function of the liver in piglets. Our findings show that early weaning significantly decreases piglet body weight and suppresses liver development. We find that early weaning also suppresses the activities of superoxide dismutase (SOD) and catalase (CAT) (p < 0.05). It could be concluded that weaning may reduce the growth performance and liver antioxidant function of piglets.

Abstract

This study examined the impact of early weaning on antioxidant function in piglets. A total of 40 Duroc × Landrace × Large White, 21-day-old piglets (half male and half female) were divided into suckling groups (SG) and weaning groups (WG). Piglets in WG were weaned at the 21st day, while the piglets in SG continued to get breastfed. Eight piglets from each group were randomly selected and slaughtered at 24th-day (SG3, WG3) and 28th-day old (SG7, WG7). The body weight, liver index, hepatocyte morphology, antioxidant enzymes activity, gene expression of antioxidant enzymes, and Nrf2 signaling in the liver of piglets were measured. The results showed that weaning caused decreased body weight (p < 0.01), lower liver weight (p < 0.01), and decreased the liver organ index (p < 0.05) of piglets. The area and size of hepatocytes in the WG group was smaller than that in the SG group (p < 0.05). We also observed that weaning reduced the activity of superoxide dismutase (SOD) and catalase (CAT) (p < 0.05) in the liver of piglets. Relative to the SG3 group, the gene expression of GSH-Px in liver of WG3 was significantly reduced (p < 0.05). The gene expression of Nrf2 in the SG3 group was higher than that in the WG3 group (p < 0.01). The gene expression of NQO1 in the SG7 group was higher than that in the WG7 group (p < 0.05). In conclusion, weaning resulted in lower weight, slowed liver development, and reduced antioxidant enzymes activity, thereby impairing liver antioxidant function and suppressing piglet growth.

Exploring With Transcriptomic Approaches the Underlying Mechanisms of an Essential Oil-Based Phytogenic in the Small Intestine and Liver of Pigs

Phytogenics are plant-based feed additives utilized in animal nutrition to support animal growth and health. Worldwide restrictions and bans on the use of antibiotic growth promoters resulted in an increased demand for in-feed alternatives including phytogenics. However, several challenges remain for technology readiness in animal industry, especially regarding the standardization of the ingredients as well as our knowledge on the cellular mechanisms underlying their biological effects. In the present study, 32 weaned piglets were allocated for 28 days to four experimental diets, a control diet, a phytogenic feed additive (PFA) diet, or the same two diets but with the addition of oxidized oil (OO) at 10%. The last two diets aimed at evaluating the antioxidant properties of PFA. At the end of the trial, the ileum and the liver of the pigs were sampled, and RNA were isolated for profiling their transcriptome via RNA sequencing (RNA-Seq). In the ileum, the gene set enrichment analysis showed that the activity of several immune pathways (NF-kB, interferon α/β, antimicrobial peptide, and collagen pathways) was reduced in piglets fed PFA compared to the control piglets. As expected, the addition of OO induced strong effects on the liver transcriptome and most likely accounted for the significant growth impairment. The likelihood ratio test across the four diets revealed a global response driven by the oxidative stress challenge with hundreds of genes associated with fatty acid β-oxidation and peroxisome in the liver. The expression levels of those genes in the piglets fed OO+PFA were much less affected by the challenge. Collectively, the effects seen at day 28 suggest that substances in the PFA formulation provide anti-inflammatory and antioxidant properties. The use of RNA-Seq in animal nutrition allows exploring and deciphering novel mechanisms of natural growth promoters.

Effects of guanidinoacetic acid and complex antioxidant supplementation on growth performance, meat quality, and antioxidant function of broiler chickens

BACKGROUND

This study was conducted to evaluate the effects of adding guanidinoacetic acid (GAA), or complex antioxidant (CA), or their combination, in diets on the growth performance, carcass traits, meat quality, and antioxidant capacity of broilers. A total of 192 25-day-old broilers were assigned to a 2 × 2 factorial design including two dietary supplements at two different levels, in which the main effects were the addition of GAA (0 or 600 mg kg^-1 ) and CA (0 or 150 mg kg^-1 ). This trial lasted for 18 days.

RESULTS

Compared with the control group, the GAA group, CA group, and GAA + CA group, decreased feed conversion ratio by 7.02%, 6.58%, and 11.40%, respectively. Guanidinoacetic supplementation increased eviscerated yield, pH_24h (P < 0.05). Complex antioxidant supplementation increased the a* values (P < 0.05). The combination of GAA and CA did not affect the carcass traits and meat quality. Guanidinoacetic acid alone and CA alone and combined with GAA and CA decreased the reactive oxygen species (ROS) level and malonaldehyde (MDA) content (P < 0.05), and the GAA + CA group had the lowest ROS level and MDA content of broilers.

CONCLUSION

Dietary supplementation of GAA, CA or their combination had beneficial effects on growth performance and breast antioxidant capacity, and the combination of GAA and CA could exert a synergistic effect in improving antioxidant capacity. © 2020 Society of Chemical Industry.

The effect of epidermal growth factor on performance and oxidative stress in piglets challenged with enterotoxigenic Escherichia coli K88

This study evaluated the efficacy of epidermal growth factor (EGF) in piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). A total of 28 piglets were assigned to the following dietary treatments for 14 d: negative control (NC) (basal diet containing supernatant without EGF), PC (NC + 2.5 g antibiotic·kg−1 feed), EGF120 [basal diet + supernatant with 120 μg EGF·kg−1 body weight (BW)·d−1], and EGF180 (basal diet + supernatant with 180 μg EGF·kg−1 BW·d−1). After a 6 d acclimation period, each pig was gavaged with 6 mL (2.4 × 1013 cfu·mL−1) of ETEC on the morning of day 7. Overall, piglets fed the EGF and PC diets tended to have higher gain to feed ratio than those fed the NC diet (P = 0.063). Pigs fed EGF diets had lower rectal temperature than those fed the NC diet at 6 h after challenge (P < 0.05). Serum and ileal malondialdehyde concentrations were higher in piglets fed the NC diet compared with those fed EGF and PC diets on days 6 and 7 after challenge, respectively (P < 0.05). In conclusion, EGF has the potential to reduce oxidative stress and body temperature elevation in piglets exposed to ETEC while supporting better feed efficiency.

Changes in carcass traits, meat quality, muscle fiber characteristics, and liver function of finishing pigs fed high level of fish oil

The study was aimed to investigate the changes in carcass traits, meat quality, muscle fiber characteristics, and liver function in pigs fed with high levels of fresh fish oil and oxidized fish oil. About 30 piglets were randomly assigned to receive basal diet plus 2% fish oil (LFO), basal diet plus 8% fish oil (HFO), or basal diet plus 8% oxidized fish oil (OFO) for 120 d. Pigs of the HFO and OFO group showed reduced carcass weight, dressing percentage, loin eye area, and increased yellowness of the longissimus dorsi muscle compared with LFO group (P < 0.05). Dietary HFO and OFO suppressed the relative expression levels of myosin heavy chain (MyHC) isoform (I and II a), glutathione peroxidase 4, and NAD(P)H: quinone oxidoreductase-1 and mitochondrial biogenesis in longissimus dorsi muscle (P < 0.05). Dietary HFO or OFO increased the serum aspartates aminotransferase, alanine aminotransferase, total bilirubin, direct bilirubin, oxidized low-density lipoprotein, liver index, and concentration of malondialdehyde (MDA) in liver (P < 0.05). In conclusion, high levels of fresh fish oil and oxidized fish oil have adverse effects on carcass traits, muscle fiber characteristics, and liver function, which may be partly due to the mitochondrial dysfunction and impaired antioxidative capacity.

Effects of Commercial Antioxidants in Feed on Growth Performance and Oxidative Stress Status of Weaned Piglets

This work aimed to evaluate the effect of adding two different commercial antioxidants (AOX) products to pre-starter and starter diets using low vitamin E (Vit E as DL-α-tocopheryl acetate) levels on the growth performance and oxidative stress of piglets for the first six weeks post-weaning (PW). They were sorted by initial body weight (BW: 6.175 ± 0.931 kg) and randomly allotted to four dietary treatments (with six replicates per treatment): a positive control (PC) and a negative control (NC) diet, with normal and low dose of vitamin E (80 and 15 mg kg^-1, respectively), both without AOX; the other two experimental diets with a low dose of vitamin E (LVE) plus LOXIDAN VD100 (LVE + AOX1) or LOXIDAN E Ros (LVE + AOX2). Growth data were recorded, and blood samples were taken, at the beginning (day 0) and at the end of each feeding period: pre-starter and starter (at days 14 and 42, respectively). No differences among dietary treatments were found with respect to growth performance in the pre-starter period (p ≥ 0.05). However, at the end of the starter period, a lower BW was found in piglets fed the NC diet compared to the other dietary treatments. Differences in daily gain and feed conversion ratio were also found either for the starter period or when the whole period was considered (p < 0.05), whereby piglets fed PC or LVE diets supplemented with AOX showed better growth performance compared to piglets fed the NC diet. Regarding Vit E (α-tocopherol) serum levels, there were no differences among treatments at day 0; but the serum values of this vitamin decreased in LVE diets at 14 and 42 days, but not in the PC. On day 42, the highest levels of α-tocopherol in liver were also found in piglets fed PC (p < 0.05). Nevertheless, in general, from a metabolic point of view and after checking the serum biochemical profile of piglets, there were no differences in other oxidative stress markers (p ≥ 0.05). The results showed that the AOX products used were able to compensate for the lower Vit E supply with respect to growth performance in the starter phase. The use of AOXs or usual levels of Vit E in feed constitutes a key factor in achieving optimal growth performance of piglets in the PW period.

Effect of dietary inclusion of antioxidants and organic trace minerals on growth performance, carcass characteristics, and meat quality of finishing pigs with pre-slaughter transportation

A total of 320 pigs (body weight = 98 ± 4 kg) were assigned to four treatments, with eight replicates (pens) per treatment. Pigs were fed the following diets: a control diet (CON), the CON diet plus antioxidant blends (AOX), organic trace minerals (OTM), or both (AOX + OTM). After the feeding trial, two pigs from each pen were selected for slaughtering right away or after transportation. The inclusion of AOX, OTM, or AOX + OTM had no significant effect on feed intake, average daily gain, and feed efficiency compared with CON (P > 0.05). The pre-transportation significantly reduced the pH value of loin meat at 24 h post mortem and leg meat at 45 min post mortem (P < 0.05). The pigs in the AOX, OTM, and AOX + OTM group had significantly lower plasma malondialdehyde (MDA) content than the CON group (P < 0.05). Pre-transportation resulted in significantly higher meat MDA contents (P < 0.05), clearly influencing the oxidative stress of pigs. The inclusion of antioxidant blends or organic trace minerals had no significant effect on the growth performance and antioxidant capacity of finishing pigs.

Effects of dietary quercetin on the antioxidative status and cecal microbiota in broiler chickens fed with oxidized oil

This study was conducted to evaluate the effects of quercetin on the antioxidant ability, intestinal barrier functions, and cecal microbiota in broiler chickens fed with oxidized soya oil. Four hundred eighty male Arbor Acres broilers were randomly assigned to 5 treatments, each involving 8 cages (12 birds per cage). The treatment groups were as follows: the control group, birds fed with basal diets containing oxidized oil, and birds fed with basal diets containing oxidized oil and supplemented with 200 ppm of quercetin, 400 ppm of quercetin, and 800 ppm of quercetin. The results showed that dietary supplementation with quercetin at a dose of 400 ppm or 800 ppm alleviated the increased serum malondialdehyde (MDA) level induced by oxidized oil on day 11 (P = 0.005) and reversed the increased MDA level in the mucosa on day 11 (P = 0.021). Quercetin significantly upregulated the transcription of nuclear factor erythroid 2–related factor 2 (Nrf2) and its downstream genes such as catalase (P < 0.001), superoxide dismutase 1 (P < 0.001), glutathione peroxidase 2 (P = 0.018), heme oxygenase-1 (HO-1) (P = 0.0), and thioredoxin (P = 0.002) and reversed the mRNA expression of HO-1 (P = 0.007) in the ileal mucosa. Tight junction protein 1 was only downregulated by oxidized oil (P = 0.013). In addition, quercetin (800 ppm) alleviated the decreased mRNA expression of mucin 2 (MUC2), which contributed to the intestinal chemical barrier (P = 0.039). The supplemental dose of 400 ppm of quercetin was able to promote Lactobacillus in the cecum, which enhanced the gastrointestinal tract health. In summary, these results indicated that quercetin ameliorated the oxidized oil–induced oxidative stress by upregulating the transcription of Nrf2 and its downstream genes to restore redox balance and reinforced the intestinal barrier via higher expression and secretion of MUC2 and facilitating the growth of Lactobacillus in the cecum. Therefore, quercetin could be a potential feed additive that can be applied in poultry production for amelioration of oxidative stress caused by oxidized oil and preventing the potential invasion of exogenous pathogens.

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

Background

This study evaluated the use of dietary vitamin E and polyphenols on growth, immune and oxidative status of weaned pigs fed peroxidized lipids. A total of 192 piglets (21 days of age and body weight of 6.62 ± 1.04 kg) were assigned within sex and weight blocks to a 2 × 3 factorial arrangement using 48 pens with 4 pigs per pen. Dietary treatments consisted of lipid peroxidation (6% edible soybean oil or 6% peroxidized soybean oil), and antioxidant supplementation (control diet containing 33 IU/kg DL-α-tocopheryl-acetate; control with 200 IU/kg additional dl-α-tocopheryl-acetate; or control with 400 mg/kg polyphenols). Pigs were fed in 2 phases for 14 and 21 days, respectively.

Results

Peroxidation of oil for 12 days at 80 °C with exposure to 50 L/min of air substantially increased peroxide values, anisidine value, hexanal, and 2,4-decadienal concentrations. Feeding peroxidized lipids decreased (P < 0.001) body weight (23.16 vs. 18.74 kg), daily gain (473 vs. 346 g/d), daily feed intake (658 vs. 535 g/d) and gain:feed ratio (719 vs. 647 g/kg). Lipid peroxidation decreased serum vitamin E (P < 0.001) and this decrease was larger on day 35 (1.82 vs. 0.81 mg/kg) than day 14 (1.95 vs. 1.38 mg/kg). Supplemental vitamin E, but not polyphenols, increased (P ≤ 0.002) serum vitamin E by 84% and 22% for control and peroxidized diets, respectively (interaction, P = 0.001). Serum malondialdehyde decreased (P < 0.001) with peroxidation on day 14, but not day 35 and protein carbonyl increased (P < 0.001) with peroxidation on day 35, but not day 14. Serum 8-hydroxydeoxyguanosine was not affected (P > 0.05). Total antioxidant capacity decreased with peroxidation (P < 0.001) and increased with vitamin E (P = 0.065) and polyphenols (P = 0.046) for the control oil diet only. Serum cytokine concentrations increased with feeding peroxidized lipids on day 35, but were not affected by antioxidant supplementation (P > 0.05).

Conclusion

Feeding peroxidized lipids negatively impacted growth performance and antioxidant capacity of nursery pigs. Supplementation of vitamin E and polyphenols improved total antioxidant capacity, especially in pigs fed control diets, but did not restore growth performance.

The changes in growth performance and lipid metabolism of pigs with yellow fat induced by high dietary fish oil

The aim of this study was to investigate the alteration in growth performance and lipid metabolism during the development of yellow fat in pigs. A total of 30 pigs (9.23 ± 0.21 kg) were assigned to three treatments: (1) low fish oil (LFO), basal diet + 2% fresh fish oil; (2) high fish oil (HFO), basal diet + 8% fresh fish oil; and (3) oxidized fish oil (OFO), basal diet + 8% OFO (peroxide value = 250 meqO2kg−1). Pigs fed HFO and OFO diets showed yellow staining of fat and decreased growth performance, including average daily gain, average daily feed intake, and final body weight (P < 0.01). The oxidized lipid markers malondialdehyde, yellowness b* of backfat, perirenal fat, and abdominal fat were markedly increased in the pigs fed with HFO and OFO (P < 0.05). Furthermore, following HFO feeding, pigs showed significant decreases in n-6 polyunsaturated fatty acid, n-6/n-3 polyunsaturated fatty acid ratio and mRNA expression levels of CCAAT-/enhancer-binding protein alpha, fatty acid synthase, lipoprotein lipase, and hormone-sensitive lipase in backfat (P < 0.01). Overall, pigs with yellow-fat trait showed decreased growth performance and altered lipid metabolism by the high fish oil feeding.

Weeping forsythia extract alleviates dexamethasone-induced oxidative injury of breast muscles in broilers

Antioxidants have been always used to improve post-slaughter meat quality in broilers subjected to stress. Forsythia suspensa extract (FSE), a traditional Chinese herbal medicine, is generally regarded as a natural source of antioxidants. Therefore, the objective of this study was to test the hypothesis that FSE could protect post-slaughter breast muscles against oxidative injury induced by dexamethasone (DEX) mimicking chronic physiological stress in poultry production. Average daily gain and feed efficiency of poultry were suppressed by DEX and improved by FSE (P < 0.05). Dexamethasone caused the decrease in the redness value and the increase in the lightness and yellowness values and drip loss of the breast muscles (P < 0.05), and FSE had the converse effects (P < 0.05). Dietary FSE supplementation decreased monounsaturated fatty acid (FA) and increased polyunsaturated FA in breast muscles of broilers (P < 0.05). In addition, FSE decreased malondialdehyde and carbonyl content in the breast muscles of DEX-treated broilers (P < 0.05). The inhibition of 1,1-diphenyl-2-picryl-hydrazyl in the breast muscles was decreased by DEX and increased by FSE (P < 0.05). Total-antioxidant capacity and glutathione peroxidase activity in the breast muscles were decreased in birds subjected to DEX and increased in birds supplemented with FSE (P < 0.05). Totally, DEX suppressed growth performance and induced breast muscle oxidative injury in broilers, and FSE supplementation improved antioxidant capacity to attenuate these adverse effects. Therefore, FSE could be a potential natural antioxidant to alleviate oxidative injury of the breast muscles in broilers and to improve the meat quality for human consumption.

Effects of Dietary Aged Maize with Oxidized Fish Oil on Growth Performance, Antioxidant Capacity and Intestinal Health in Weaned Piglets

Simple Summary

In China, large quantities of maize are stored in grain depots for two years or more to mitigate the risk of natural disasters impacting feed supplies. However, it is unknown whether the use of long-term stored maize in diets will impair growth performance of piglets, and whether additional dietary oxidants would further exacerbate the effects. This study investigates the effects of dietary aged maize with the supplementation of different levels of oxidized fish oil on growth performance, nutrient digestibility, serum antioxidant activity and gut health in piglets and tries to provide a theoretical foundation for the better use of aged maize in swine production. The results of this study showed that aged maize had no significant effect on growth performance, diarrhea and nutrient digestibility of the piglets, but it did reduce serum antioxidant capacity. When oxidized fish oil was added, aged maize reduced serum antioxidant capacity further, inhibited the expressions of genes related to intestinal nutrient transport, promoted intestinal inflammation, and also reduced the apparent total tract digestibility (ATTD) of nutrients, increased diarrhea and finally reduced the growth performance of piglets. Thus, the use of aged maize in the diet of the piglets may be not feasible, especially when other oxidation-inducing factors existed, which would exacerbate the negative effects of the aged maize.

Abstract

This study aimed to determine the effects of dietary aged maize with supplementation of different levels of oxidized fish oil on growth performance, nutrient digestibility, serum antioxidant activity and gut health in piglets. Forty-two piglets were arranged in 2 × 3 factorial treatments in a complete randomized block design with seven replicates per treatment and one pig per replicate for 28 d. Diets included twp types of maize (normal maize or aged maize) and three levels of oxidized fish oil (OFO) (3% non-oxidized fish oil (0% OFO), 1.5% OFO and 1.5% non-oxidized fish oil (1.5% OFO), and 3% OFO (3% OFO). Results showed that dietary aged maize did not affect growth performance, diarrhea, and the apparent total tract digestibility (ATTD) of nutrients in piglets (p > 0.05). However, aged maize increased malonaldehyde (MDA) content and decreased total antioxidant capacity (T-AOC) in serum on both 14th and 28th days (p < 0.05) compared to the normal maize groups. Meanwhile, compared with normal maize, dietary aged maize showed a slight, but not significant (p > 0.10) decrease in total superoxide dismutase (T-SOD) activity and VE content in serum on the 14th day. In addition, aged maize significantly decreased GLUT2 mRNA expression (p < 0.05) and tended to increase (p < 0.10) TNF-α and IL-6 mRNA expression in jejunal mucosa. Compared with non-oxidized fish oil, oxidized fish oil resulted in the decrease of the 14–28 d and 0–28 d ADG, as well as the ATTD of dry matter (DM), ether extract (EE), organic matter (OM) (p < 0.05), whereas the increase in diarrhea index (p < 0.05) and F/G of the whole period (p < 0.05). Oxidized fish oil decreased serum T-AOC on both the 14th and the 28th days (p < 0.05), and decreased serum T-SOD activity and VE content on the 28th day (p < 0.05), whereas increased serum MDA content on the 28th day (p < 0.05) and 14th day (p < 0.10) compared with fresh fish oil. Meanwhile, MUC2 (p < 0.05) and SGLT1 (p < 0.10) mRNA expression in jejunal mucosa were decreased compared with non-oxidized fish oil. In addition, dietary oxidized fish oil tended to decrease 14–28 d ADFI and the ATTD of CP (p < 0.10), and piglets fed oxidized fish oil significantly decreased 14–28 d ADFI, the ATTD of CP, GLUT2 and SGLT1 mRNA expressions in jejunal mucosa when piglet also fed with aged maize (p < 0.05). Collectively, these results indicated that dietary oxidized fish oil decreased growth performance and nutrients digestibility of piglets fed with aged maize. This nutrient interaction may be mediated by inhibiting intestinal nutrient transporter, inducing intestinal inflammation, and reducing antioxidant capacity.

Lipid peroxidation impairs growth and viability of nursery pigs reared under commercial conditions1

The objective of this study was to investigate the impact of lipid peroxidation in a dose-dependent manner on growth, health, and oxidative stress status of nursery pigs. A total of 2,200 weaned pigs (5.95 ± 0.20 kg BW) were housed in 100 pens (22 pigs per pen) in a randomized complete block design based on initial BW and sex. Pigs were randomly assigned within blocks to 5 dietary treatments, consisting of a corn-soybean meal-based diet supplemented with 5% of either control corn oil (iodine value = 118, FFA = 0.06%, anisidine value = 3, peroxide value = 3 mEq/kg oil) or peroxidized corn oil (iodine value = 120, FFA = 0.35%, anisidine value = 30, peroxide value = 163 mEq/kg oil). These 2 diets were blended to obtain 5 levels of peroxidation with final treatments designated as 0 (diet with 5% control oil), 25%, 50%, 75%, and 100% (diet with peroxidized corn oil) peroxidation. Diets were fed ad libitum for 43 d. Blood samples were collected on d 33 from 20 pigs per treatment to determine serum oxidative stress markers and vitamin E concentrations and again on d 43 (14 d after vaccination) to determine immune response to porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (Mhyo). Gain:feed ratio decreased linearly (P = 0.023) with increasing peroxidation, but pen ADG and ADFI were not affected. Number of pigs removed for medical treatment, total number medically treated, pigs culled for low end weight, and mortality increased, and full-value pigs linearly decreased (P < 0.04) with increasing peroxidation. Consequently, total pen gain (weight of viable pigs that remained in test pens at the end of the study minus weight of pigs placed) decreased linearly (P < 0.01) with increasing peroxidation. Antibody titers to Mhyo and PCV2 increased postvaccination (P < 0.001), but did not differ due to dietary treatment. Serum concentrations of malondialdehyde, 8-hydroxy-2'-deoxyguanosine, and protein carbonyl were not affected by peroxidation. Total antioxidant capacity and serum vitamin E concentrations decreased (P = 0.01) linearly with increasing peroxidation. Data show a dose-dependent negative impact of lipid peroxidation on pig productivity when determined under field population conditions, being primarily manifested by increased mortality, number of pigs medically treated, and number of culled pigs (≤13.6 kg BW). Results underscore the importance of proper assessment of lipid peroxidation as part of quality control to prevent oxidative stress and performance losses in weaned pigs.

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

Background

Maize oil is abundantly used in foods and feeds and is highly susceptible to oxidation. Consequently, commercially available antioxidants should be evaluated for effectiveness against lipid oxidation in swine diets. Our study was conducted to evaluate growth performance of nursery pigs fed oxidized maize oil and to determine effects of using antioxidants on oxidative status in a 2 × 2 factorial design. Two hundred eight weaned pigs were blocked by initial BW into 13 blocks, resulting in 4 pigs per pen and 13 pens per treatment. Dietary treatments included 6% unoxidized or oxidized maize oil, and 0 or 60 mg/kg of tert-butylhydroquinone (TBHQ), which was added after lipid oxidation. Data for growth performance were collected from 5 time periods of a two-phase feeding program (Phase 1 = d 0 to 12 and Phase 2 = d 13 to 34). Serum and liver samples were collected from one pig per pen, which had initial BW closest to average BW to determine oxidative status on d 34.

Results

Oxidized maize oil was heated for 12 h at 185 °C with 12 L/min of air, yielding a peroxide value (PV) of 5.98 mEq O₂/kg and TBARS of 0.11 mg MDA eq/g. Addition of TBHQ to diets containing oxidized maize oil decreased PV by 37% and increased the oil stability index by 69%. Final BW, ADG, ADFI, and G:F of pigs were not different among the four dietary treatments. However, pigs fed oxidized maize oil tended (P <  0.08) to increase hepatosomatic index by 5% compared with those fed unoxidized oil, and this was not affected by adding TBHQ. The serum vitamin E concentration of pigs fed oxidized maize oil was less (P < 0.03) than pigs fed unoxidized oil, but this reduction was not reversed by adding TBHQ. Finally, the serum and liver selenium concentration were not different among the treatments.

Conclusions

The addition of TBHQ did not affect growth performance and vitamin E status in pigs fed moderately oxidized maize oil, but TBHQ reduced lipid oxidation, enhanced the oil stability, and appeared to reduce oxidative stress.

Effects of thermally oxidized canola oil and tannic acid supplementation on nutrient digestibility and microbial metabolites in finishing pigs1

The present study investigated the effects of oxidized canola oil and tannic acid (TA) supplementation on nutrient digestibility and microbial metabolites in finishing pigs. Four experimental diets were formulated to include 5% of either fresh canola oil (0 mEq/kg of peroxide value) or oxidized canola oil (180 mEq/kg of peroxide value). An equal portion of each diet was supplemented with 0.1% TA. Eight pigs (initial body weight of 82.89 ± 2.26 kg) were surgically fitted with a T-cannula at the distal ileum. At the beginning of the experiments, all pigs were fed a nitrogen-free diet for 7 d. Then, they were assigned to 4 dietary treatments according to an incomplete replicated 4 × 3 Latin square design with 3 periods to give 6 replicates per treatment. Each experimental period lasted for 9 d, starting with a 5-d adaptation period followed by 2 consecutive 2-d periods for fecal (day 6 and day 7) and ileal digesta (day 8 and day 9) collection. The inclusion of oxidized oil reduced (P < 0.05) the standardized ileal digestibility (SID) of Pro and the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of NDF. Also, pigs fed the oxidized oil tended to have lower (P ≤ 0.10) lactate and ammonia-nitrogen concentrations in the ileum and lower (P ≤ 0.10) acetate and propionate concentrations in the feces than those fed the fresh oil. The supplementation of 0.1% TA reduced (P < 0.05) the AID of NDF and the ATTD of gross energy, crude protein, and NDF. Additionally, the TA-supplemented diet tended to have a lower (P ≤ 0.10) digestible energy content than the nonsupplemented diet. Pigs fed the TA-supplemented diet showed reduced (P < 0.05) AID and SID of His, Cys, and Pro compared with those fed the nonsupplemented diet. There were interactive effects (P < 0.05) of oxidized oil and TA supplementation on acetate, isovalerate, total short chain fatty acids, and pH level in the ileum. In conclusion, the results indicated that the effects of oxidized oil are greater on microbial activities rather than nutrient digestibility. Although negative effects of dietary TA supplementation were observed in relation to nutrient digestibility, TA supplementation was found to ameliorate these negative effects of oxidized oil on microbial metabolites. Therefore, further studies are required to investigate the interaction between dietary oxidized oil and TA in relation with the gut microbiota in pigs.

Dietary vitamin E affects small intestinal histomorphology, digestive enzyme activity, and the expression of nutrient transporters by inhibiting proliferation of intestinal epithelial cells within jejunum in weaned piglets1

Vitamin E (VE) is an indispensable vitamin in piglet feed formula. Among other things, it affects tissues including small intestine tissues and in particular its major unit intestinal epithelial cells. Previously, limited in vivo experiments have focused on the effect of VE on the intestine, particularly digestion and absorption. VE has been shown to inhibit proliferation of some types of cells. This experiment was conducted to test the hypothesis that VE affects intestinal functions by influencing the intestinal epithelial cell proliferation. Thirty 21-d old weaned [(Yorkshire × Landrace) × Duroc] piglets with BWs of 6.36 ± 0.55 kg were randomly divided into five VE-containing feeding formula groups. The treatments were (i) 0 IU (control), (ii) 16 IU, (iii) 32 IU, (iv) 4. 80 IU, and (v) 5. 160 IU. The treatments lasted 14 d. At the end of the experiment, all subjects were sacrificed to obtain blood and tissue samples. The results suggest that VE did not affect the growth performance. VE did tend to decrease jejunal crypt depth (linear, P = 0.056) and villus width (linear, P < 0.05). Sucrase activity significantly decreased in the adding 80 IU VE compared with the control (P < 0.05). Jejunal crypt, cell proliferation in 80 IU group significantly decreased compared with the control group (P < 0.05). This study suggests that dietary VE may affect intestinal morphology and functions by inhibiting weaned piglet jejunal epithelial cell proliferation.

Immunomodulatory, antioxidant and intestinal morphology-regulating activities of alfalfa polysaccharides in mice

The effects of alfalfa polysaccharides (APS) on immunomodulatory and antioxidant functions, as well as intestinal morphology were investigated in vivo in this study. Sixty-four mice were randomly divided into four groups and administered 0, 200, 400 or 800 mg/kg/d body weight APS via gavage for 28 days. The blood parameters and metabolites, viscera indices, antioxidant enzyme activities and intestinal morphology were measured. The results showed that the oral administration of APS improved the immune functions of mice, significantly enhanced the white blood cells and lymphocyte counts, and led to improvements in spleen and thymus indices. APS exhibited significant antioxidant activity by enhancing total antioxidant capacity, superoxide dismutase and glutathione peroxidase activities in heart, kidney and liver, and decreasing the malondialdehyde levels of heart and liver. Moreover, administration of APS potently enhanced the small intestinal villous height and the villus-to-crypt ratio, and decreased the crypt depth of duodenum in mice. Therefore, we can conclude that APS possesses pronounced immunomodulatory activities, and plays an important role in the prevention of oxidative stresses and in the improvement of intestinal morphology in the immunological system in vivo. APS thus shows potential for the development as an effective natural immunomodulatory and antioxidant agent.

Assessment of the efficacy of a grape seed waste in counteracting the changes induced by aflatoxin B1 contaminated diet on performance, plasma, liver and intestinal tissues of pigs after weaning

The aim of this study was to investigate the potential of a grape seed byproduct to mitigate the harmful damage produced by aflatoxin B1 (AFB1) at systemic level in plasma and liver as well as at local level in the gastrointestinal tract in weaned piglets. Twenty four crossbred pigs (TOPIG) were randomly assigned to one of four experimental diets: 1)- control diet (normal compound feed for starter piglets without mycotoxin), 2)- AFB1 diet (compound feed contaminated with 320 ppb pure AFB1), 3)- GS diet (compound feed including 8% of grape seed meal), 4)- AFB1+GS diet (compound feed containing 8% of grape seed meal contaminated with 320 ppb AFB1) for 30 days. The results showed that pigs fed AFB1 diet had altered performance (-25.1%), increased the thiobarbituric substances (TBARS) concentration wile reduced total antioxidant capacity and activity of antioxidant enzymes (CAT, SOD and GPx) in plasma and organs. AFB1 produced a dual effect on inflammatory response by increasing the level of pro-inflammatory cytokines in liver and colon and decreasing these cytokines in duodenum. The inclusion of grape seed in the diet of AFB1 intoxicated pigs enhanced the antioxidant enzymes activity, decreased the pro-inflammatory cytokines and TBARS level and ameliorated the growth performance of AFB1-treated animals. These findings suggest that grape waste is a promising feed source in counteracting the harmful effect of aflatoxin B1.

Impact of a dietary challenge with peroxidized oil on the glutathione redox status and integrity of the small intestine in weaned piglets

Glutathione (GSH) is considered to play an important role in maintaining the integrity of the small intestine. In piglets, altered mucosal GSH levels might therefore be involved in weaning-induced changes of the small intestinal morphology and barrier function. To test this hypothesis, we aimed to challenge the mucosal GSH redox status during the first 28 days after weaning, by feeding diets containing 5% fresh linseed oil (CON), or 2.5% (OF1) or 5% (OF2) peroxidized linseed oil (peroxide value 225 mEq O2/kg oil) and exploring the effects on gut integrity. Piglets were pair-fed and had a total daily feed allowance of 32 g/kg BW. A fourth treatment included animals that were fed the control diet ad libitum (ACON). Animals were sampled at days 5 and 28 post-weaning. The malondialdehyde (MDA) concentration and GSH redox status (GSH/GSSG Eh) were determined in blood, liver and small intestinal mucosa. Histomorphology of the duodenal and jejunal mucosa was determined, and Ussing chambers were used to assess fluorescein isothiocyanate dextran (FD4) and horseradish peroxidase (HRP) fluxes across the mucosa. Results show that peroxidized linseed oil imposed an oxidative challenge at day 28, but not at day 5 post-weaning. At day 28, increasing levels of dietary peroxides to pair-fed pigs linearly increased MDA levels in duodenal and jejunal mucosa. Moreover, FD4 fluxes were significantly increased in OF1 (+75%) and OF2 (+64%) in the duodenum, and HRP fluxes tended (P=0.099) to show similar differences, as compared to CON. This co-occurred with a significant 11 mV increase of the hepatic GSH/GSSG Eh, potentiated by a significantly increased GSH peroxidase activity for treatments OF1 (+47%) and OF2 (+63%) in liver as compared to CON. Furthermore; duodenal HRP flux significantly correlated with the hepatic glutathione disulphide (GSSG) level (r=0.650), as also observed in the jejunum for hepatic GSSG (r=0.627) and GSH/GSSG Eh (r=0.547). The jejunal permeability was not affected, but FD4 and HRP fluxes significantly correlated with the local GSH (r=0.619; r=0.733) and GSSG (r=0.635; r=0586) levels. Small intestinal histomorphology was not affected by dietary lipid peroxides, nor were there any correlations found with the GSH redox system. To conclude, under oxidative stress conditions, jejunal barrier function is related to the local and hepatic GSH redox system. It is suggested that the hepatic GSH system participates in the elimination of luminal peroxides, and thereby impacts on duodenal barrier function.

Influence of feeding thermally peroxidized soybean oil on oxidative status in growing pigs

The objectives of this study were to determine whether feeding thermally processed peroxidized soybean oil (SO) induces markers of oxidative stress and alters antioxidant status in pig tissue, blood, and urine. Fifty-six barrows (25.3 ± 3.3 kg initial BW) were randomly assigned to dietary treatments containing 10% fresh SO (22.5 °C) or thermally processed SO (45 °C for 288 h, 90 °C for 72 h, or 180 °C for 6 h), each with constant air infusion rate of 15 liters/minute. Multiple indices of lipid peroxidation were measured in the SO including peroxide value (2.0, 96, 145, and 4.0 mEq/kg for 22.5, 45, 90, and 180 °C processed SO, respectively) and p-anisidine value (1.2, 8.4, 261, and 174 for 22.5, 45, 90, and 180 °C processed SO, respectively); along with a multitude of aldehydes. Pigs were individually housed and fed ad libitum for 49 d which included a 5 d period in metabolism crates for the collection of urine and serum for measures of oxidative stress. On day 49, pigs were euthanized to determine liver weight and analyze liver-based oxidative stress markers. Oxidative stress markers included serum, urinary, and liver thiobarbituric acid reactive substances (TBARS), and urinary F2-isoprostanes (ISP) as markers of lipid damage; serum and liver protein carbonyls (PC) as a marker of protein damage; and urinary and liver 8-hydroxy-2'-deoxyguanosine (8-OH-2dG) as a marker of DNA damage. Superoxide dismutase (SOD), and catalase activity (CAT) were measured in liver, glutathione peroxidase activity (GPx) was measured in serum and liver, and ferric reducing antioxidant power (FRAP) was measured in serum and urine as determinants of antioxidant status. Pigs fed 90 °C SO had greater urinary ISP (P = 0.02), while pigs fed the 45 °C SO had elevated urinary TBARS (P = 0.02) in comparison to other treatment groups. Pigs fed 45 °C and 90 °C SO had increased serum PC concentrations (P = 0.01) and pigs fed 90 °C SO had greater (P = 0.01) liver concentration of 8-OH-2dG compared to pigs fed the other SO treatments. Furthermore, pigs fed 90 °C SO had reduced serum GPx activity in comparison to pigs fed fresh SO (P = 0.01). In addition, pigs fed 180 °C SO had increased liver CAT activity (P = 0.01). Liver GPx and SOD or serum and urinary FRAP were not affected by dietary treatment. These results indicate that dietary peroxidized soybean oil induced oxidative stress by increasing serum PC while diminishing serum GPx, increasing urinary ISP and TBARS, and increasing 8-OH-2dG and CAT in liver.

ω-3 Fatty Acids and Cardiovascular Diseases: Effects, Mechanisms and Dietary Relevance

ω-3 fatty acids (n-3 FA) have, since the 1970s, been associated with beneficial health effects. They are, however, prone to lipid peroxidation due to their many double bonds. Lipid peroxidation is a process that may lead to increased oxidative stress, a condition associated with adverse health effects. Recently, conflicting evidence regarding the health benefits of intake of n-3 from seafood or n-3 supplements has emerged. The aim of this review was thus to examine recent literature regarding health aspects of n-3 FA intake from fish or n-3 supplements, and to discuss possible reasons for the conflicting findings. There is a broad consensus that fish and seafood are the optimal sources of n-3 FA and consumption of approximately 2-3 servings per week is recommended. The scientific evidence of benefits from n-3 supplementation has diminished over time, probably due to a general increase in seafood consumption and better pharmacological intervention and acute treatment of patients with cardiovascular diseases (CVD).

Characteristics of lipids and their feeding value in swine diets

In livestock diets, energy is one of the most expensive nutritional components of feed formulation. Because lipids are a concentrated energy source, inclusion of lipids are known to affect growth rate and feed efficiency, but are also known to affect diet palatability, feed dustiness, and pellet quality. In reviewing the literature, the majority of research studies conducted on the subject of lipids have focused mainly on the effects of feeding presumably high quality lipids on growth performance, digestion, and metabolism in young animals. There is, however, the wide array of composition and quality differences among lipid sources available to the animal industry making it essential to understand differences in lipid composition and quality factors affecting their digestion and metabolism more fully. In addition there is often confusion in lipid nomenclature, measuring lipid content and composition, and evaluating quality factors necessary to understand the true feeding value to animals. Lastly, advances in understanding lipid digestion, post-absorption metabolism, and physiological processes (e.g., cell division and differentiation, immune function and inflammation); and in metabolic oxidative stress in the animal and lipid peroxidation, necessitates a more compressive assessment of factors affecting the value of lipid supplementation to livestock diets. The following review provides insight into lipid classification, digestion and absorption, lipid peroxidation indices, lipid quality and nutritional value, and antioxidants in growing pigs.