Resveratrol alleviates oxidative stress induced by oxidized soybean oil and improves gut function via changing gut microbiota in weaned piglets

BACKGROUND

Oxidized soybean oil (OSO) has been shown to impair growth and exacerbate inflammation, leading to intestinal barrier injury in animals. Recent evidence suggests important roles for resveratrol (RES) in the promoting growth performance, antioxidant capacity, anti-inflammatory, and regulate intestinal barriers in animals. Therefore, The objectives of this study are to investigate the effects of dietary RES (purity 98%) supplementation on the growth performance, antioxidant capacity, inflammatory state, and intestinal function of weaned piglets challenged with OSO.

METHODS

A total of 28 castrated weaned male piglets with a similar body weight of 10.19 ± 0.10 kg were randomly assigned to 4 dietary treatments for 28-d feeding trial with 7 replications per treatment and 1 piglet per replicate. Treatments were arranged as a 2 × 2 factorial with oil type [3% fresh soybean oil (FSO) vs. 3% OSO] and dietary RES (0 vs. 300 mg/kg).

RESULTS

The results showed that relative to the FSO group, OSO stress tended to decrease the average daily feed intake (ADFI), and decreased the activity levels of lipase, villus/crypt ratio (VCR), the mRNA expression of FABP1, SOD2, IL-10 and ZO-1 in the jejunum, and SOD2, GPX1, occludin and ZO-1 in the colon, the levels of acetic acid in the colonic digesta, whereas up-regulated the mRNA expression of IL-1β and TNF-α in the jejunum (P < 0.05). Moreover, dietary supplementation with RES increased ether extract (EE), the activity levels of sucrase, lipase, α-amylase, villus height (VH) and VCR, the mRNA expression of FABP1, SOD2, IL-10 and occludin in the jejunum, and FABP1, PPAR-γ, GPX1, occludin and ZO-1 in the colon, and the abundance of Firmicutes, acetic and propionic acid, but decreased the levels of D-lactic acid in the plasma, the abundance of Bacteroidetes in the colonic digesta of weaned piglets compared to the non-RES group (P < 0.05). Meanwhile, in the interaction effect analysis, relative to the OSO group, dietary RES supplementation in the diets supplemented with OSO increased the activity levels of trypsin, VH in the jejunum, the abundance of Actinobacteria, the levels of butyric acid of weaned piglets, but failed to influence the activity levels of trypsin and VH, Actinobacteria abundance, the levels of butyric acid when diets were supplemented with FSO (interaction, P < 0.05). Relative to the OSO group, dietary RES supplementation in the diets supplemented with OSO decreased the activity levels of DAO in the plasma of weaned piglets but failed to influence the activity levels of DAO when diets were supplemented with FSO (interaction, P < 0.05). Relative to the FSO group, dietary RES supplementation in the diets supplemented with FSO decreased the level of propionic acid, whereas RES supplementation failed to influence the level of propionic acid when the diet was supplemented with OSO (interaction, P < 0.01).

CONCLUSIONS

Inclusion of OSO intensified inflammatory states and impaired the intestinal health characteristics of weaned piglets. Dietary RES supplementation improved the antioxidant capacity, anti-inflammatory activity, and intestinal morphology. Further studies showed that the protective effects of RES on gut health could be linked to the decreased abundance of Prevotella_1, Clostridium_sensu_stricto_6, and Prevotellaceae_UCG003 and increased levels of acetic and propionic acid.

Identification of Protective Amino Acid Metabolism Events in Nursery Pigs Fed Thermally Oxidized Corn Oil

Feeding thermally oxidized lipids to pigs has been shown to compromise growth and health, reduce energy digestibility, and disrupt lipid metabolism. However, the effects of feeding oxidized lipids on amino acid metabolism in pigs have not been well defined even though amino acids are indispensable for the subsistence of energy metabolism, protein synthesis, the antioxidant system, and many other functions essential for pig growth and health. In this study, oxidized corn oil (OCO)-elicited changes in amino acid homeostasis of nursery pigs were examined by metabolomics-based biochemical analysis. The results showed that serum and hepatic free amino acids and metabolites, including tryptophan, threonine, alanine, glutamate, and glutathione, as well as associated metabolic pathways, were selectively altered by feeding OCO, and more importantly, many of these metabolic events possess protective functions. Specifically, OCO activated tryptophan-nicotinamide adenosine dinucleotide (NAD⁺) synthesis by the transcriptional upregulation of the kynurenine pathway in tryptophan catabolism and promoted adenine nucleotide biosynthesis. Feeding OCO induced oxidative stress, causing decreases in glutathione (GSH)/oxidized glutathione (GSSG) ratio, carnosine, and ascorbic acid in the liver but simultaneously promoted antioxidant responses as shown by the increases in hepatic GSH and GSSG as well as the transcriptional upregulation of GSH metabolism-related enzymes. Moreover, OCO reduced the catabolism of threonine to α-ketobutyrate in the liver by inhibiting the threonine dehydratase (TDH) route. Overall, these protective metabolic events indicate that below a certain threshold of OCO consumption, nursery pigs are capable of overcoming the oxidative stress and metabolic challenges posed by the consumption of oxidized lipids by adjusting antioxidant, nutrient, and energy metabolism, partially through the transcriptional regulation of amino acid metabolism.

Feeding thermally processed spray-dried egg whites, singly or in combination with 15-acetyldeoxynivalenol or peroxidized soybean oil on growth performance, digestibility, intestinal morphology, and oxidative status in nursery pigs

Two experiments (EXP) determined the susceptibility of spray-dried egg white (SDEW) to oxidation (heating at 100 °C for 72 h; thermally processed, TP) and whether feeding TP-SDEW, 15-acetyldeoxynivalenol (15-ADON), or peroxidized soybean oil (PSO), singularly or in combination, would affect pig performance, intestinal morphology, digestibility, and markers of oxidative stress in nursery pigs. In EXP 1, 32 pigs (7.14 kg body weight, BW) were placed individually into pens and fed diets containing either 12% SDEW, 6% TP-SDEW plus 6% SDEW, or 12% TP-SDEW. Performance was measured at the end of the 24-d feeding period with biological samples harvested following euthanasia. In EXP 2, 64 pigs (10.6 kg BW) were placed individually into pens and fed diets containing 7.5% soybean oil or PSO, 10% SDEW or TP-SDEW, and diets without or with 3 mg 15-ADON/kg diet in a 2 × 2 × 2 factorial arrangement. Performance was measured at the end of the 28-d feeding period with biological samples harvested following euthanasia. In EXP 1, dietary treatment did not affect pig performance, apparent ileal digestibility of amino acids (AAs), apparent total tract digestibility (ATTD) of gross energy (GE) or nitrogen (N), ileal crypt depth, or villi height:crypt depth ratio (P > 0.05). The effects of feeding TP-SDEW on protein damage in the plasma and liver (P < 0.05) were variable. In EXP 2, there were no three-way interactions and only one two-way interactions among dietary treatments on parameters evaluated. There was no effect of feeding TP-SDEW on ATTD of GE or N, intestinal morphology, or on oxidative markers in the plasma, liver, or ileum (P > 0.05). There was no effect of feeding diets containing added 15-ADON on ATTD of GE, ileal AA digestibility, intestinal morphology, oxidative markers in the plasma, liver, or ileum, or pig performance (P > 0.05). Feeding pigs diets containing PSO resulted in reduced ATTD of GE and N, plasma vitamin E concentration, and pig performance (P < 0.01) but did not affect intestinal morphology or oxidative markers in the liver or ileum (P > 0.05). In conclusion, it was difficult to induce protein oxidation in SDEW and when achieved there were limited effects on performance, digestibility, intestinal morphology, and oxidative status. Furthermore, singly adding 15-A-DON to a diet had no effect on the animal. At last, adding PSO reduces animal performance, but has limited effect on digestibility, intestinal morphology, and oxidative status in nursery pigs.

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.

Effect of chelated source of additional zinc and selenium on performance, yolk fatty acid composition, and oxidative stability in laying hens fed with oxidised oil

1. The following study determined whether the effects of the combined addition of zinc amino acid complex (ZA) and selenomethionine (SM) was superior to their single addition in controlling the oxidative stress induced by dietary oxidised fat in laying hens.2. Two hundred and forty 32-week-old laying hens were divided into the following dietary treatments (each consisting of six replicates of eight birds): 1) a fresh soy oil (FSO) diet; 2) an oxidised soy oil (OSO) diet; 3) an OSO diet plus 20 mg zinc as ZA/kg (OSO+ZA); 4) an OSO diet plus 0.2 mg selenium as SM/kg (OSO+SM); and 5) an OSO diet plus ZA and SM (OSO+ZA+SM).3. After 10 weeks of feeding hens, feed intake, egg production, and egg mass in the OSO+ZA+SM group were similar to the FSO group but better (P<0.05) than those in the OSO group. Shell thickness and shell breaking strength were significantly improved by the OSO+ZA and OSO+ZA+SM treatments.4. Increases in the yolk concentrations of palmitic acid and total saturated fatty acids (SFA), and decreases in yolk linoleic acid, n-6 polyunsaturated fatty acids (PUFA), total PUFA, and PUFA/SFA ratio were induced by dietary oxidised fat which were normalised (P<0.05) by OSO+SM and OSO+ZA+SM.5. An increase (P<0.05) in malondialdehyde and a decrease in 2,2-diphenyl-picrylhydrazyl radical scavenging activity in the yolk, induced by dietary oxidised fat, was significantly improved by all dietary supplementations, but only birds fed the OSO+ZA+SM diet exhibited similar values to those fed FSO.6. In conclusion, the simultaneous inclusion of organic zinc plus selenium in the oxidised fat diets was beneficial for improving egg-laying performance, yolk fatty acid profile, and oxidative stability, but not for internal egg quality, compared with either zinc or selenium alone in laying hens.

Evidence-Based Challenges to the Continued Recommendation and Use of Peroxidatively-Susceptible Polyunsaturated Fatty Acid-Rich Culinary Oils for High-Temperature Frying Practises: Experimental Revelations Focused on Toxic Aldehydic Lipid Oxidation Products

In this manuscript, a series of research reports focused on dietary lipid oxidation products (LOPs), their toxicities and adverse health effects are critically reviewed in order to present a challenge to the mindset supporting, or strongly supporting, the notion that polyunsaturated fatty acid-laden frying oils are "safe" to use for high-temperature frying practises. The generation, physiological fates, and toxicities of less commonly known or documented LOPs, such as epoxy-fatty acids, are also considered. Primarily, an introduction to the sequential autocatalytic peroxidative degradation of unsaturated fatty acids (UFAs) occurring during frying episodes is described, as are the potential adverse health effects posed by the dietary consumption of aldehydic and other LOP toxins formed. In continuance, statistics on the dietary consumption of fried foods by humans are reviewed, with a special consideration of French fries. Subsequently, estimates of human dietary aldehyde intake are critically explored, which unfortunately are limited to acrolein and other lower homologues such as acetaldehyde and formaldehyde. However, a full update on estimates of quantities derived from fried food sources is provided here. Further items reviewed include the biochemical reactivities, metabolism and volatilities of aldehydic LOPs (the latter of which is of critical importance regarding the adverse health effects mediated by the inhalation of cooking/frying oil fumes); their toxicological actions, including sections focussed on governmental health authority tolerable daily intakes, delivery methods and routes employed for assessing such effects in animal model systems, along with problems encountered with the Cramer classification of such toxins. The mutagenicities, genotoxicities, and carcinogenic potential of aldehydes are then reviewed in some detail, and following this the physiological concentrations of aldehydes and their likely dietary sources are considered. Finally, conclusions from this study are drawn, with special reference to requirements for (1) the establishment of tolerable daily intake (TDI) values for a much wider range of aldehydic LOPs, and (2) the performance of future nutritional and epidemiological trials to explore associations between their dietary intake and the incidence and severity of non-communicable chronic diseases (NCDs).

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.

Feeding oxidized chicken byproduct meal impacts digestibility more than performance and oxidative status in nursery pigs

Rendered products from the meat industry provide quality proteins in diets for companion animals. These proteins are exposed to extreme temperatures during processing leading to the potential for decreased diet digestibility and subsequent growth performance. While this would impact production efficiency in livestock species, oxidized ingredients in companion animal diets may impact health and longevity. The objective of this study was to determine the extent to which a feedstuff containing oxidized protein and lipid affect diet digestibility, growth performance, and oxidative stress in nursery pigs. A total of 56 male pigs (21 d of age, initial body weight 5.51 ± 0.65 kg) were randomly assigned to one of the four dietary treatments in a 2 × 2 factorial arrangement with two levels of heat and two levels of antioxidant (AOX). Diets were fed for 35 d and growth performance was measured, while total tract digestibility and nitrogen (N) balance was determined during the trial on day 18–20. Blood plasma was collected on day 34 and jejunum, colon, and liver tissues were collected on day 35 to analyze for markers of oxidative stress. Average daily feed intake (ADFI) was reduced in pigs fed diets without AOXs (P = 0.02). Additionally, pigs consuming diets containing heated chicken byproduct (CBP) meal had decreased gain:feed (GF; P = 0.02). There was an interaction between heat and AOX (P = 0.02) where heating CBP reduced N digestibility in the presence of an AOX but did not have an impact when AOX was not present. The removal of AOX resulted in reduced GE digestibility (P < 0.01). Dry matter (P < 0.01), ash (P < 0.01), and protein (P < 0.01) digestibility were reduced (P < 0.01) as a result of heating. Furthermore, heating (P =0.01) as well as absence of AOX (P =0.01) resulted in reduced digestible energy. No difference was detected in N retention suggesting that oxidation reduces digestibility but has no impact on N utilization. This is supported by the fact that systemic oxidative stress was not consistently affected by heating or AOX inclusion. These results suggest that feeding pigs CBP containing oxidized proteins and lipids did not induce oxidative stress. However, feeding young pigs CBP containing oxidized proteins and lipids did result in reduced energy and nutrient digestibility as well as negatively affected feed efficiency. Because CBP is commonly used in companion animal diets, it is reasonable to revisit their impacts on those species.

Influence of feeding thermally peroxidized lipids on growth performance, lipid digestibility, and oxidative status in nursery pigs

Three experiments were conducted to evaluate oil source and peroxidation status (experiment 1) or peroxidized soybean oil (SO; experiments 2 and 3) on growth performance, oxidative stress, and digestibility of dietary ether extract (EE). In experiment 1, palm oil (PO), poultry fat (PF), canola oil (CO), and SO were evaluated, while in experiments 2 and 3, only SO was evaluated. Lipids were either an unheated control (CNT) or thermally processed at 90 °C for 72 hr, being added at 10%, 7.5%, or 3% of the diet in experiments 1, 2, and 3, respectively. In experiment 1, 288 pigs (body weight, BW, 6.1 kg) were fed 1 of 8 factorially arranged treatments with the first factor being lipid source (PO, PF, CO, and SO) and the second factor being peroxidation status (CNT or peroxidized). In experiment 2, 216 pigs (BW 5.8 kg) were fed 1 of 6 treatments consisting of 100%, 90%, 80%, 60%, 20%, and 0% CNT SO blended with 0%, 10%, 20%, 40%, 80%, and 100% peroxidized SO, respectively. In experiment 3, 72 pigs (BW 5.8 kg) were fed either CNT or peroxidized SO. Pigs were fed 21 d with feces collected on day 12 or 14 and pigs bled on day 12 blood collection. In experiment 1, an interaction between oil source and peroxidation status was observed for averaged daily gain (ADG) and average daily feed intake (ADFI; P = 0.10) which was due to no impact of feeding pigs peroxidized PO, PF, or SO on ADG or ADFI compared with feeding pigs CNT PO, PF, or SO, respectively; while pigs fed peroxidized CO resulted in reduced ADG and ADFI compared with pigs fed CNT CO. There was no interaction between oil source and peroxidation status, and no lipid source effect on gain to feed ratio (GF; P ≥ 0.84), but pigs fed the peroxidized lipids had a lower GF compared with pigs fed the CNT lipids (P = 0.09). In experiment 2, feeding pigs diets containing increasing levels of peroxidized SO resulted in reduced ADG (quadratic, P = 0.03), ADFI (linear, P = 0.01), and GF (quadratic, P = 0.01). In experiment 3, feeding peroxidized SO at 3% of the diet reduced ADG (P = 0.11) and ADFI (P = 0.13), with no observed change in GF (P = 0.62). Differences in plasma protein carbonyls, glutathione peroxidase, and vitamin E due to feeding peroxidized lipids were inconsistent across the 3 experiments. Digestibility of dietary EE was reduced in pigs fed peroxidized PO or SO (P = 0.01, experiment 1) and peroxidized SO in experiments 2 and 3 (P ≤ 0.02). In conclusion, the peroxidation status of dietary lipids consistently affects growth performance and EE digestibility but has a variable effect on measures of oxidative stress.

Impact of dietary oxidized protein on oxidative status and performance in growing pigs

Rendered products from the meat industry can provide economical quality sources of proteins to the animal and feed industry. Similar to lipids, rendered proteins are susceptible to oxidation, yet the stability of these proteins is unclear. In addition, interest in understanding how oxidative stress can impact efficiency in production animals is increasing. Recent studies show that consumption of oxidized lipids can lead to a change in the oxidative status of the animal as well as decreases in production efficiency. To date, little is known about how consumption of oxidized proteins impacts oxidative status and growth performance. The objectives of this study were to determine if feeding diets high in oxidized protein to growing pigs would: 1) impact growth performance and 2) induce oxidative stress. Thirty pigs (42 d old; initial body weight [BW] 12.49 ± 1.45 kg) were randomly assigned to one of three dietary treatments with increasing levels of oxidized protein. Spray-dried bovine plasma was used as the protein source and was either unheated upon arrival, heated at 45 °C for 4 d, or heated at 100 °C for 3 d. Diets were fed for 19 d and growth performance was measured. Blood plasma (days 0 and 18), jejunum, colon, and liver tissues (day 19) were collected to analyze for markers of oxidative stress (e.g., protein oxidation, lipid oxidation, DNA damage, and glutathione peroxidase activity). Average daily gain (ADG;P < 0.01) and average daily feed intake (ADFI;P < 0.01) had a positive linear relationship to increased protein oxidation, but there was no effect on gain to feed ratio. Furthermore, protein (P = 0.03) and fat (P < 0.01) digestibility were reduced with increased protein oxidation in the diet. Crypt depth showed a positive linear relationship with dietary protein oxidation levels (P = 0.02). A trend was observed in liver samples where pigs fed the plasma heated to 45 °C had increased lipid oxidation compared with pigs fed the plasma either unheated or heated to 100 °C (P = 0.09). DNA damage in the jejunum tended to have a linear relationship with the dietary protein oxidation level (P = 0.07). Even though results suggest dietary oxidized protein did not induce oxidative stress during short-term feeding, differences in performance, gut morphology, and digestibility are likely a result of reduced protein availability.

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.

A Transcriptome Analysis Reveals that Hepatic Glycolysis and Lipid Synthesis Are Negatively Associated with Feed Efficiency in DLY Pigs

Feed efficiency (FE) is an important trait in the porcine industry. Therefore, understanding the molecular mechanisms of FE is vital for the improvement of this trait. In this study, 6 extreme high-FE and 6 low-FE pigs were selected from 225 Duroc × (Landrace × Yorkshire) (DLY) pigs for transcriptomic analysis. RNA-seq analysis was performed to determine differentially expressed genes (DEGs) in the liver tissues of the 12 individuals, and 507 DEGs were identified between high-FE pigs (HE- group) and low-FE pigs (LE- group). A gene ontology (GO) enrichment and pathway enrichment analysis were performed and revealed that glycolytic metabolism and lipid synthesis-related pathways were significantly enriched within DEGs; all of these DEGs were downregulated in the HE- group. Moreover, Weighted gene co-expression analysis (WGCNA) revealed that oxidative phosphorylation, thermogenesis, and energy metabolism-related pathways were negatively related to HE- group, which might result in lower energy consumption in higher efficiency pigs. These results implied that the higher FE in the HE- group may be attributed to a lower glycolytic, energy consumption and lipid synthesizing potential in the liver. Furthermore, our findings suggested that the inhibition of lipid synthesis and glucose metabolic activity in the liver may be strategies for improving the FE of DLY pigs.

Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, gut integrity, and oxidative stress in nursery pigs

The objectives of the current experiments were to evaluate the effect of feeding soybean oil (SO) with different levels of peroxidation on lipid, N, and GE digestibility, gut integrity, oxidative stress, and growth performance in nursery pigs. Treatments consisted diets 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 an air infusion of 15 L/min, with postprocessing peroxide values of 7.6, 11.5, 19.1, and 13.4 mEq/kg and p-anisidine values of 1.92, 6.29, 149, and 159, for the 22.5 °C, 45 °C, 90 °C and 180 °C processed SO, respectively. In experiment 1, 64 barrows (7.1 ± 0.9 kg initial BW) were randomly allotted into 2 rooms of 32 pens and individually fed their experimental diets for 21 d, with a fresh fecal sample collected on day 20 for determination of GE and lipid digestibility. In experiment 2, 56 barrows (BW 9.16 ± 1.56 kg) were placed into individual metabolism crates for assessment of GE, lipid, and N digestibility and N retention. Urinary lactulose to mannitol ratio was assessed to evaluate in vivo small intestinal integrity, and urine and plasma were collected to analyze for markers of oxidative stress. Pigs were subsequently euthanized to obtain liver weights and analyze the liver for markers of oxidative stress. In experiment 1, pigs fed the SO thermally processed at 90 °C had reduced ADG (P = 0.01) and ADFI (P = 0.04) compared to pigs fed the other SO treatment groups, with no differences noted among pigs fed the 22.5 °C, 45 °C, and 180 °C SO treatments. No effects of feeding thermally processing SO on dietary GE or lipid digestibility (P > 0.10) were noted in either experiment. In experiment 2, there was no dietary effect of feeding peroxidized SO on the DE:ME ratio, N digestibility, or N retained as a percent of N digested, on the urinary ratio of lactulose to mannitol, on serum, urinary, or liver thiobarbituric acid reactive substances, on plasma protein carbonyls, or on urinary or liver 8-OH-2dG (P > 0.10). In experiment 2, pigs fed the SO thermally processed at 90 °C had the greatest isoprostane concentrations in the serum (P ≤ 0.01) and urine (P ≤ 0.05) compared to pigs fed the unprocessed SO. These results indicate that the change in fatty acid composition and/or the presence of lipid peroxidation products in peroxidized SO may reduce ADG and ADFI in nursery pigs, but appears to have no impact on GE, lipid, or N digestibility, or gut permeability. These data suggest that the presence of lipid peroxidation products may affect certain markers of oxidative stress.

Changes in markers of lipid oxidation and thermal treatment in feed-grade fats and oils

BACKGROUND

Oxidized feed lipids have been shown to have detrimental effects on food animal growth and metabolism. The present study aimed to measure classes of lipid oxidation products (LOP) in feed-grade oils at temperatures representing production and storage conditions.

RESULTS

There were significant oil type × time interactions in the accumulation of primary and secondary LOP. At 22.5 °C, peroxide value (PV), a marker for the primary phase of lipid oxidation, increased most in fish oil (FO), followed by tallow (TL), soybean oil (SO), linseed oil (LO) and modified algae oil (MAO), whereas palm oil (PO) showed no appreciable increase in PV. Secondary LOP, such as p-anisidine value, hexanal, 2,4,-decadienal, polymerized triacylglycerols and total polar compounds, increased only in FO. At 45 °C, FO and SO produced both primary and secondary LOP, whereas MAO, PO and TL had slower rates of PV increase and no secondary LOP. At 90 °C and 180 °C, all oils except for FO accumulated both primary and secondary LOP.

CONCLUSIONS

Higher polyunsaturated fatty acid:saturated fatty acid oils and higher temperatures produced greater quantities of primary and secondary LOP. However, unrefined TL was more prone to oxidation at 22.5 °C than predicted, whereas LO was more stable than predicted, indicating that pro-oxidant and antioxidant compounds can markedly influence the rate of oxidation. Measuring both primary and secondary LOP will provide better information about the oxidative status of feed oils and provide better information about which classes of LOP are responsible for detrimental health effects in animals. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.

Identification of C9-C11 unsaturated aldehydes as prediction markers of growth and feed intake for non-ruminant animals fed oxidized soybean oil

Background

The benefits of using the oxidized oils from rendering and recycling as an economic source of lipids and energy in animal feed always coexist with the concerns that diverse degradation products in these oxidized oils can negatively affect animal health and performance. Therefore, the quality markers that predict growth performance could be useful when feeding oxidized oils to non-ruminants. However, the correlations between growth performance and chemical profiles of oxidized oils have not been well examined. In this study, six thermally oxidized soybean oils (OSOs) with a wide range of quality measures were prepared under different processing temperatures and processing durations, including 45 °C-336 h; 67.5 °C-168 h; 90 °C-84 h; 135 °C-42 h; 180 °C-21 h; and 225 °C-10.5 h. Broilers and nursery pigs were randomly assigned to diets containing either unheated control soybean oil or one of six OSOs. Animal performance was determined by measuring body weight gain, feed intake, and gain to feed ratio. The chemical profiles of OSOs were first evaluated by common indicative tests, including peroxide value, thiobarbituric acid reactive substances, p-anisidine value, free fatty acids, oxidized fatty acids, unsaponifiable matter, insoluble impurities, and moisture, and then analyzed by the liquid chromatography-mass spectrometry-based chemometric analysis.

Results

Among common quality indicators, p-anisidine value (AnV), which reflects the level of carbonyl compounds, had the greatest inverse correlation with the growth performance of both broilers and pigs, followed by free fatty acids and oxidized fatty acids. Among the 17 aldehydes identified in OSOs, C9-C11 alkenals, especially 2-decenal and 2-undecenal, had stronger inverse correlations (r < − 0.8) with animal performance compared to C5-C8 saturated alkanals, suggesting that chain length and unsaturation level affect the toxicity of aldehydes.

Conclusions

As the major lipid oxidation products contributing to the AnV, individual C9-C11 unsaturated aldehydes in heavily-oxidized oils could function as effective prediction markers of growth and feed intake in feeding non-ruminants.

Effects of dietary fatty acids on gut health and function of pigs pre- and post-weaning

Fatty acids (FA) play a major role in relation to mucosal immune responses, epithelial barrier functions, oxidative stress, and inflammatory reactions. The dietary FA composition and the molecular structures (chain length and number of double bonds) influence digestion, absorption and metabolism, and the bioactivity of the FA. Piglets post-weaning having an immature intestine and not fully formed immune functions are very vulnerable to invading microorganisms. Manipulation of the milk FA composition via sow nutrition, or inclusion of dietary fat sources in the feed for newly weaned pigs, may be used as a strategic tool to enhance pig performance and their gut health and function pre- and post-weaning. Medium-chain fatty acids (MCFA) are absorbed directly into the portal blood and may contribute to immediate energy for the enterocytes. In addition, the MCFA, similarly to the short-chain fatty acids (SCFA), possess antibacterial effects and may thereby prevent overgrowth of pathogenic bacteria in the gastrointestinal tract. The essential FA, linoleic (LA) and α-linolenic (ALA) FA, form the building blocks for the long-chain polyunsaturated n-3 and n-6 FA. The conversion of ALA and LA into n-3 and n-6 eicosanoids, respectively, influences the molecular structures of metabolites and inflammatory reactions and other immune responses upon bacterial challenges. Dietary manipulation of the lactating sow influences the transfer of the n-3 and n-6 polyunsaturated fatty acids (PUFA) from the sow milk to the piglet and the incorporation of the FA into piglet enteric tissues and cell membranes, which exerts bioactivity of importance for immune responses and the epithelial barrier function. Especially, the n-3 PUFA present in fish oil seem to influence the gut health and function of pigs, and this is of importance during the transition periods such as post-weaning in which piglets are prone to inflammation. The proportion of unsaturated FA in the cell membranes influences the susceptibility to oxidative stress. Oxidative stress accompanies infectious diseases, and the development of lipid peroxides and other reactive oxygen products may be harmful to the epithelial barrier function. Fatty acid peroxides from the feed may also be absorbed with other lipid-solubles and thereby harm the intestinal function. Hence, antioxidative protection is important for the enteric cells. In conclusion, manipulation of the dietary FA composition can influence the gut health and function in pigs and may support a normal immune system and modulate resistance to infectious diseases during especially stressful phases of a pig's life such as post-weaning.

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.

Effects of chlorogenic acid-enriched extract from Eucommia ulmoides Oliver leaf on growth performance and quality and oxidative status of meat in finishing pigs fed diets containing fresh or oxidized corn oil

To investigate the effects of chlorogenic acid-enriched extract (CGAE) from Eucommia ulmoides Oliver leaf on growth performance and quality and oxidative status of meat in pigs fed diets containing fresh or oxidized corn oil, a total of 180 barrows (initial body weight: 81.6 ± 2.08 kg) were randomly allocated into 6 diet treatments (5 replicate pens per treatment and 6 barrows per pen) in a 2 × 3 factorial design with corn oil (fresh or oxidized corn oil at 5% inclusion of diet) and CGAE (0, 500 or 1,000 mg/kg of diet containing fresh or oxidized corn oil) as main factors. The experiment lasted for 6 weeks. Dietary oxidized oil reduced average daily gain (ADG, p < .05) and average daily feed intake (ADFI, p < .01) of pigs and pH₂₄ (p < .05), total antioxidant capacity (T-AOC, p < .01), glutathione peroxidase (GPx, p < .05) and sarcoplasmic reticulum Ca²⁺ -ATPase (SERCA, p < .05) activities in meat and increased drip loss (p < .01), cooking loss (p < .05), malondialdehyde (p < .01) and carbonyl (p < .01) contents and mRNA expression of superoxide dismutase 1 (SOD1, p < .05) in meat. Dietary CGAE supplementation at 1,000 mg/kg increased (p < .05) ADG and ADFI of pigs and pH₂₄ , T-AOC, T-SOD, GPx and SERCA activities and mRNA expression of SOD1 in meat and reduced (p < .05) drip loss, cooking loss, carbonyl and malondialdehyde contents in meat. No interaction effects between oxidized corn oil and CGAE were found in pigs. Overall, dietary CGAE supplementation at 1,000 mg/kg improved growth performance and quality and oxidative status of meat in pigs subjected or not to oxidative stress induced by dietary oxidized oil.

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.

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.

Influence of feeding thermally peroxidized soybean oil to finishing pigs on carcass characteristics, loin quality, and shelf life of loin chops

The objective of this study was to evaluate the effect of feeding soybean oil (SO) with varying levels of peroxidation on carcass traits and shelf life of loins. Fifty-six barrows were randomly assigned to 1 of 4 diets 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 infused with air at a rate of 15 liter/min. Individually housed pigs were provided ad libitum access to feed for 81 d. At 82 d, pigs were slaughtered and hot carcass weight and liver weights were recorded. Carcass characteristics and fresh loin quality were evaluated 1 d postmortem. Loin chops from each carcass were overwrap-packaged and subjected to a 10-d simulated retail display. Daily measurements of L*, a*, b*, reflectance, and visual discoloration were conducted, evaluation of cooking loss and Warner-Bratzler shear force (WBSF) was conducted on chops stored 0, 5, and 10 d, and thiobarbituric acid reactive substances (TBARS) were evaluated on chops stored 0 and 10 d. Shelf life-related data were analyzed as a completely randomized design with repeated measures in time, with storage location (shelf) as a random effect. Carcasses of 90 °C pigs weighed 6.0, 8.6, and 6.9 kg less (P < 0.03) than 22.5 °C, 45 °C, and 180 °C carcasses, respectively. Livers of 90 °C and 180 °C pigs were 14.3% and 11.7%, respectively, heavier (P ≤ 0.02) than those from pigs fed 22.5 °C SO, with livers of 45 °C being intermediate. Livers of 90 °C pigs represented 0.12 percentage units less (P = 0.02) of ending live weight than livers of 180 °C pigs, and 180 °C livers were 0.12 percentage units less (P < 0.01) of ending live weight than those from pigs fed 22.5 °C SO, with 45 °C being intermediate. There was no difference (P ≥ 0.19) in back fat depth, loin muscle area, or estimated carcass lean percentage among SO treatments, nor was there an effect (P ≥ 0.13) of SO on any early post-mortem loin quality traits or loin composition. There was no effect (P > 0.14) of SO on cooking loss, WBSF, L*, a*, b*, hue angle, reflectance, discoloration, or TBARS; however, there was a tendency (P = 0.09) for chops of 45 °C pigs to have greater (P < 0.04) chroma than either 22.5 °C or 180 °C, with 90 °C being intermediate. Overall, feeding SO cooked at 90 °C for 72 h resulted in reduced carcass weight and dressing percentage; however, there was no evidence that feeding peroxidized SO was detrimental to shelf life of loin chops.

Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, and gut integrity in finishing pigs

Consumption of peroxidized lipids has been shown to reduce pig performance and energy and lipid digestibility. Objectives of the current study were to evaluate the effect of feeding soybean oil (SO) with different levels of peroxidation on growth performance, lipid, N, and GE digestibility, plasma Trp, and gut integrity in finishing pigs. Fifty-six barrows (46.7 ± 5.1 kg initial BW) were randomly assigned to one of four diets in each of two dietary phases, containing either 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 infused with of 15 L/min of air. Peroxide values were 2.0, 17.4, 123.6, and 19.4 mEq/kg; 2,4-decadienal values were 2.07, 1.90, 912.15, and 915.49 mg/kg; and 4-hydroxynonenal concentrations were 0.66, 1.49, 170.48, and 82.80 mg/kg, for the 22.5, 45, 90, and 180 °C processed SO, respectively. Pigs were individually housed and fed ad libitum for 81 d to measure growth performance, including a metabolism period to collect urine and feces for determination of GE, lipid, N digestibility, and N retention. Following the last day of fecal and urine collection when pigs were in the metabolism crates, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability, while markers of oxidative stress were evaluated in plasma, urine, and liver. There were no differences observed in ADFI (P = 0.91), but average daily gain (ADG) and gain:feed G:F were decreased in pigs fed 90 °C SO diet (P ≤ 0.07) compared to pigs fed the other SO diets. Pigs fed the 90 and 180 °C SO had the lowest (P = 0.05) DE as a % of GE compared to pigs fed the 22.5 °C SO, with pigs fed the 45 °C SO being intermediate. Lipid digestibility was similarly affected (P = 0.01) as energy digestibility, but ME as a % of DE was not affected by dietary treatment (P = 0.16). There were no effects of lipid peroxidation on N digested, N retained, or the urinary lactulose:mannitol ratio (P ≥ 0.25). Pigs fed the SO processed at 90 and 180 °1C had lower concentrations (P < 0.01) of plasma Trp compared to pigs fed the 22.5 and 45 °C SO treatments. Pigs fed 90 °C SO had the greatest (P < 0.01) concentrations of F2-isoprostane in plasma and urine thiobarbituric acid reactive substances compared to the other SO treatments. These results indicate that the change in FA composition and/or the presence of lipid peroxidation products in peroxidized SO may reduce ADG, G:F, and digestibility of GE and ether extract, but has little impact on N digestibility and balance or on gut permeability.

Identification of activation of tryptophan-NAD+ pathway as a prominent metabolic response to thermally oxidized oil through metabolomics-guided biochemical analysis

Consumption of thermally oxidized oil is associated with metabolic disorders, but oxidized oil-elicited changes in the metabolome are not well defined. In this study, C57BL/6 mice were fed the diets containing either control soybean oil or heated soybean oil (HSO) for 4 weeks. HSO-responsive metabolic events were examined through untargeted metabolomics-guided biochemical analysis. HSO directly contributed to the presence of new HSO-derived metabolites in urine and the decrease of polyunsaturated fatty acid-containing phospholipids in serum and the liver. HSO disrupted redox balance by decreasing hepatic glutathione and ascorbic acid. HSO also activated peroxisome proliferator-activated receptors, leading to the decrease of serum triacylglycerols and the changes of cofactors and products in fatty acid oxidation pathways. Most importantly, multiple metabolic changes, including the decrease of tryptophan in serum; the increase of NAD⁺ in the liver; the increases of kynurenic acid, nicotinamide and nicotinamide N-oxide in urine; and the decreases of the metabolites from pyridine nucleotide degradation in the liver indicated that HSO activated tryptophan-NAD⁺ metabolic pathway, which was further confirmed by the upregulation of gene expression in this pathway. Because NAD⁺ and its metabolites are essential cofactors in many HSO-induced metabolic events, the activation of tryptophan-NAD⁺ pathway should be considered as a central metabolic response to the exposure of HSO.

Influence of feeding thermally peroxidized soybean oil on growth performance, digestibility, and gut integrity in growing pigs

Consumption of highly peroxidized oils has been shown to affect pig performance and oxidative status through the development of compounds which differ according to how oils are thermally processed. The objective of this study was to evaluate the effect of feeding varying degrees of peroxidized soybean oil (SO) on parameters of growth performance; lipid, N, and GE digestibility, gut integrity in growing pigs, and plasma Trp. Fifty-six barrows (25.3 ± 3.3 kg initial BW) were randomly assigned to one of four diets containing either 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 an air infusion of 15 L/min. Peroxide values for the 22.5, 45, 90, and 180 °C processed SO were 2.0, 96, 145, and 4.0 mEq/kg, respectively; 2,4-decadienal values for 22.5, 45, 90, and 180 °C processed SO were 2.11,5.05, 547.62, and 323.57 mg/kg, respectively; and 4-hydroxynonenal concentrations of 0.05, 1.05, 39.46, and 25.71 mg/kg with increasing SO processing temperature. Pigs were individually housed and fed ad libitum for a 49 d period to determine the effects of SO peroxidation status on growth performance, including a metabolism period for assessing GE and N digestibility, and N retention. In vivo urinary lactulose to mannitol ratio was also assessed to evaluate potential changes in small intestinal integrity. Although there were no differences observed in ADFI (P = 0.19), ADG was decreased in pigs fed 90 °C SO diet (P = 0.01), while G:F was increased (P = 0.02) in pigs fed 45 °C SO diet compared to the other SO diets. Pigs fed the 90 °C processed SO had the lowest (P = 0.01) DE as a percentage of GE, whereas ME as a percentage of DE was lowest (P = 0.05) in pigs fed the 180 °C SO and 90 °C SO followed by 45 °C SO and fresh SO. Ether extract (EE) digestibility was lowest (P = 0.01) in pigs fed 90 °C SO followed by pigs fed 180 °C SO, 45 °C SO, and fresh SO. The percent of N retained was greatest (P = 0.01) in pigs fed fresh SO followed by pigs fed 45 °C SO, 180 °C SO, and 90 °C, respectively. There were no differences observed among SO treatments for urinary lactulose to mannitol ratio (P = 0.60). Pigs fed SO processed at 90 °C and 180 °C had lower concentrations (P < 0.01) of serum Trp compared to pigs fed the 22.5 °C and 45 °C SO treatments. The presence of lipid peroxidation products, namely several aldehydes, contained in the 90 °C SO diet reduced ADG, GE and EE digestibility, and N balance, but had no impact on gut permeability.

Dietary supplementation of pyrroloquinoline quinone disodium protects against oxidative stress and liver damage in laying hens fed an oxidized sunflower oil-added diet

The protective effects of dietary pyrroloquinoline quinone disodium (PQQ.Na2) supplementation against oxidized sunflower oil-induced oxidative stress and liver injury in laying hens were examined. Three hundred and sixty 53-week-old Hy-Line Gray laying hens were randomly allocated into one of the five dietary treatments. The treatments included: (1) a diet containing 2% fresh sunflower oil; (2) a diet containing 2% thermally oxidized sunflower oil; (3) an oxidized sunflower oil diet with 100 mg/kg of added vitamin E; (4) an oxidized sunflower oil diet with 0.08 mg/kg of PQQ.Na2; and (5) an oxidized sunflower oil diet with 0.12 mg/kg of PQQ.Na2. Birds fed the oxidized sunflower oil diet showed a lower feed intake compared to birds fed the fresh oil diet or oxidized oil diet supplemented with vitamin E (P=0.009). Exposure to oxidized sunflower oil increased plasma malondialdehyde (P<0.001), hepatic reactive oxygen species (P<0.05) and carbonyl group levels (P<0.001), but decreased plasma glutathione levels (P=0.006) in laying hens. These unfavorable changes induced by the oxidized sunflower oil diet were modulated by dietary vitamin E or PQQ.Na2 supplementation to levels comparable to the fresh oil group. Dietary supplementation with PQQ.Na2 or vitamin E increased the activities of total superoxide dismutase and glutathione peroxidase in plasma and the liver, when compared with the oxidized sunflower oil group (P<0.05). PQQ.Na2 or vitamin E diminished the oxidized sunflower oil diet induced elevation of liver weight (P=0.026), liver to BW ratio (P=0.001) and plasma activities of alanine aminotransferase (P=0.001) and aspartate aminotransferase (P<0.001) and maintained these indices at the similar levels to the fresh oil diet. Furthermore, oxidized sunflower oil increased hepatic DNA tail length (P<0.05) and tail moment (P<0.05) compared with the fresh oil group. Dietary supplementation of PQQ.Na2 or vitamin E decreased the oxidized oil diet induced DNA tail length and tail moment to the basal levels in fresh oil diet. These results indicate that PQQ.Na2 is a potential antioxidant and is as effective against oxidized oil-related liver injury in laying hens as vitamin E. The protective effects of PQQ.Na2 against liver damage induced by oxidized oil may be partially due to its role in the scavenging of free radicals, inhibiting of lipid peroxidation and enhancing of antioxidant defense systems.

Peroxidised dietary lipids impair intestinal function and morphology of the small intestine villi of nursery pigs in a dose-dependent manner

The objective of this study was to investigate the effect of increasing degrees of lipid peroxidation on structure and function of the small intestine of nursery pigs. A total of 216 pigs (mean body weight was 6·5 kg) were randomly allotted within weight blocks and sex and fed one of five experimental diets for 35 d (eleven pens per treatment with three to four pigs per pen). Treatments included a control diet without added lipid, and diets supplemented with 6 % soyabean oil that was exposed to heat (80°C) and constant oxygen flow (1 litre/min) for 0, 6, 9 and 12 d. Increasing lipid peroxidation linearly reduced feed intake (P<0·001) and weight gain (P=0·024). Apparent faecal digestibility of gross energy (P=0·001) and fat (P<0·001) decreased linearly as the degree of peroxidation increased. Absorption of mannitol (linear,P=0·097) andd-xylose (linear,P=0·089), measured in serum 2 h post gavage with a solution containing 0·2 g/ml ofd-xylose and 0·3 g/ml of mannitol, tended to decrease progressively as the peroxidation level increased. Increasing peroxidation also resulted in increased villi height (linear,P<0·001) and crypt depth (quadratic,P=0·005) in the jejunum. Increasing peroxidation increased malondialdehyde concentrations (quadratic,P=0·035) and reduced the total antioxidant capacity (linear,P=0·044) in the jejunal mucosa. In conclusion, lipid peroxidation progressively diminished animal performance and modified the function and morphology of the small intestine of nursery pigs. Detrimental effects were related with the disruption of redox environment of the intestinal mucosa.

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.

Evaluating the quality of feed fats and oils and their effects on pig growth performance

Feed fats and oils provide significant amounts of energy to swine diets, but there is large variation in composition, quality, feeding value, and price among sources. Common measures of lipid quality include moisture, insolubles, and unsaponifiables (MIU), titer, and free fatty acid content, but provide limited information regarding their feeding value. Lipid peroxidation is an important quality factor related to animal growth performance and health, but maximum tolerable limits in various lipids have not been established. Several indicative assays can be used to detect the presence of various peroxidation compounds, but due to the complexity and numerous compounds produced and degraded during peroxidation process, no single method can adequately determine the extent of peroxidation. Until further information is available, using a combination of peroxide value, thiobarbituric acid reactive substances (TBARS), and anisidine value appear to provide a reasonable assessment of the extent of peroxidation in a lipid at a reasonable cost. However, fatty acid composition of the lipid being evaluated should be considered when selecting specific assays. Predictive tests can also be used to estimate the stability or susceptibility of lipids to peroxidation and include active oxygen method, oil stability index, and oxygen bomb method. A review of 16 published studies with pigs has shown an average decrease of 11.4% in growth rate, 8.8% feed intake fed isocaloric diets containing peroxidized lipids compared to diets containing unperoxidized lipids of the same source. Furthermore, serum vitamin E content was generally reduced and serum TBARS content was increased when peroxidized lipids were fed in these studies, suggesting that feeding peroxidized lipids negatively affects metabolic oxidative status of pigs. However, it is unclear if antioxidants are useful additions to lipids to maintain optimal nutritional value, or if their addition to swine diets is beneficial in overcoming a metabolic oxidative challenge.

Influence of thermally oxidized vegetable oils and animal fats on energy and nutrient digestibility in young pigs

A total of 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial design plus a corn-soybean meal control diet to evaluate the effect of lipid source and peroxidation level on DE, ME, and apparent total tract digestibility (ATTD) of DM, GE, ether extract (EE), N, and C in young pigs. Main effects were lipid source (corn oil [CN], canola oil [CA], poultry fat [PF], and tallow [TL]) and peroxidation level (original lipids [OL], slow oxidation [SO] of lipids heated for 72 h at 95°C, or rapid oxidation [RO] of lipids heated for 7 h at 185°C). Pigs were provided ad libitum access to diets for 28 d followed by an 8-d period of controlled feed intake equivalent to 4% BW daily. Diets were formulated based on the ME content of CA with the standardized ileal digestible Lys, Met, Thr, Trp, total Ca, and available P:ME balanced relative to NRC (1998) recommendations. Lipid peroxidation analysis indicated that compared with the OL, SO and RO had a markedly increased concentrations of lipid peroxidation products, and the increase of peroxidation products in CN and CA were greater than those in PF and TL. Addition of lipids to diets increased (P < 0.05) ATTD of EE and tended to improve (P = 0.06) ATTD of GE compared with pigs fed the control diet. Feeding CN or CA increased (P < 0.05) ATTD of DM, GE, EE, N, and C compared with feeding TL, while feeding PF improved (P < 0.05) ATTD of GE and EE and tended to increase (P = 0.06) ATTD of C compared with TL. Pigs fed CN had increased (P = 0.05) percentage N retention than pigs fed TL. No peroxidation level effect or interaction between lipid source and peroxidation level on DE and ME was observed. Lipid source tended (P = 0.08) to affect DE but not ME values of experimental lipids (P > 0.12). Digestible energy values for CA (8,846, 8,682, and 8,668 kcal/kg) and CN (8,867, 8,648, and 8,725 kcal/kg) were about 450 kcal/kg greater than that of TL (8,316, 8,168, and 8,296 kcal/kg), with PF being intermediate (8,519, 8,274, and 8,511 kcal/kg), for OL, SO, and RO lipids, respectively, respectively. In conclusion, lipid source affected ATTD of dietary DM, GE, EE, N, and C, and N retention and tended to influence the DE value of the lipid but did not significantly affect their ME value. Rapid and slow heating of lipids used in this study increased lipid peroxidation products but had no detectable effects on nutrient and energy digestibility as well as DE and ME values of the various lipids.