Dietary peroxidized maize oil affects the growth performance and antioxidant status of nursery pigs

Animal Feed Science and Technology 216 (2016) 251–261

Contents lists available at ScienceDirect

Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci

Dietary peroxidized maize oil affects the growth performance and antioxidant status of nursery pigs Andrea R. Hanson a,1 , Pedro E. Urriola a , Lei Wang b , Lee J. Johnston c , Chi Chen b , Gerald C. Shurson a,∗ a b c

Department of Animal Science, 385 AnSci/VetMed Bldg., 1988 Fitch Avenue, University of Minnesota, St. Paul, MN 55108, USA Department of Food Science and Nutrition, 330 ABLMS, 1354 Eckles Ave., St. Paul, MN 55108, USA West Central Research and Outreach Center, 46352 State Hwy 329, Morris, MN 56267, USA

a r t i c l e

i n f o

Article history: Received 11 January 2016 Received in revised form 23 March 2016 Accepted 24 March 2016 Keywords: Caloric efficiency Growth performance Maize oil Metabolic oxidation Weaned pigs Peroxidation

a b s t r a c t This experiment was conducted to evaluate the effects of increasing dietary levels of peroxidized maize oil on growth performance and antioxidant status of nursery pigs. Weanling barrows (n = 128; initial body weight (BW) = 6.3 ± 1.4 kg) were blocked by initial BW and assigned randomly to 1 of 32 pens. Within block, pens were assigned randomly to 1 of 4 dietary treatments: 90 g/kg unheated maize oil, 60 g/kg unheated maize oil +30 g/kg rapidly peroxidized (RO) maize oil, 30 g/kg unheated maize oil +60 g/kg RO maize oil, or 90 g/kg RO maize oil. Diets were formulated to contain identical levels of total maize oil and standardized ileal digestible Lys to metabolizable energy (ME) ratios. Maize oil was heated for 12 h at 185 ◦ C (air flow rate = 12 L/min) to yield RO (PV = 5.7 meq O2 /kg; thiobarbituric acid reactive substances = 26.7 mg malondialdehyde eq/kg) maize oil. A 3-phase feeding program (phase 1 = d 0–4, phase 2 = d 4–14, and phase 3 = d 14–35) was used, and average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and energetic efficiency (g ADG/MJ of ME intake) were determined. Serum was collected on d 0, 14, and 35 from 1 pig per pen that was subsequently harvested to obtain liver and heart tissue. Final BW (19.5 vs 18.5 ± 0.6 kg for 0 vs 90 g/kg RO maize oil; P < 0.15) and ADG (377.5 vs 347.0 ± 13.6 g for 0 vs 90 g/kg RO maize oil; P ≤ 0.10) tended to decline linearly with increasing dietary RO, but ADFI was not affected. Consequently, G:F (P < 0.05) declined linearly by 1.4–4% with increasing dietary concentrations of RO maize oil. The ␣-tocopherol content of serum declined with increasing dietary concentrations of RO maize oil (linear and cubic; P < 0.01). These data suggest that RO maize oil negatively affects growth performance and the efficiency of energy utilization of nursery pigs linearly and reduces serum ␣-tocopherol content. © 2016 Elsevier B.V. All rights reserved.

Abbreviations: ADFI, average daily feed intake; ADG, average daily gain; ATTD, apparent total tract digestibility; BW, body weight; DMO, distillers maize oil; DDGS, dried distillers grains with solubles; G:F, gain to feed ratio; HPLC, high performance liquid chromatography; MDA, malondialdehyde; ME, metabolizable energy; MHD, Mulberry Heart Disease; PUFA, polyunsaturated fatty acids; PV, peroxide value; SID, standardized ileal digestible; TBARS, thiobarbituric acid reactive substances. ∗ Corresponding author. E-mail address: [email protected] (G.C. Shurson). 1 Present address: SVC Research, P.O. BOX 269 St. Peter, MN 56082, USA. http://dx.doi.org/10.1016/j.anifeedsci.2016.03.027 0377-8401/© 2016 Elsevier B.V. All rights reserved.

252

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

1. Introduction Lipids in maize and maize dried distillers grains with solubles (DDGS) provide a substantial portion of energy in United States swine diets. Distiller’s maize oil (DMO) is extracted prior to manufacturing DDGS at more than 85% of ethanol plants in the United States and it is used for the production of biodiesel and animal feeds (Renewable Fuels Association, 2015). However, maize oil contains 540 g/kg polyunsaturated fatty acids (PUFA) that are susceptible to peroxidation (NRC, 2012). Peroxidation is accelerated by exposure to heat, air, moisture, and pro-oxidant metals, which may be introduced during feed ingredient processing and storage. Animal fats, vegetable oils, and other lipid-rich feed ingredients may be peroxidized to varying amounts depending on the temperature and duration of thermal exposure (Dibner et al., 2011; Song and Shurson, 2013). Peroxidation degrades fatty acids into numerous secondary and tertiary peroxidation compounds (Spiteller et al., 2001; Seppanen and Csallany, 2002; Belitz et al., 2009), and degrades indigenous vitamin E (Seppanen and Csallany, 2002; Liu et al., 2014c). Feeding peroxidized lipids reduces gain efficiency (McGill et al., 2011a, b; Tavárez et al., 2011), growth rate (Boler et al., 2012; Liu et al., 2014b), and antioxidant status (Boler et al., 2012; Liu et al., 2014b) of swine and broilers. At the cellular level, peroxidized lipids attack lipid membranes, impair cell function and integrity, and contribute to apoptosis (Gutteridge, 1995). Maximal dietary thresholds for inclusion of peroxidized lipids have not been established, and little information exists on the effects of increasing dietary concentrations of peroxidized lipids on growth performance of pigs. Therefore, the objective of this experiment was to investigate the effect of increasing dietary levels of peroxidized maize oil in iso-caloric diets on the growth and antioxidant status of nursery pigs. Maize oil was selected as the lipid source because of its high concentration of PUFA (NRC, 2012), and the increasing use of DMO in swine diets. 2. Materials and methods 2.1. Pig care, management, and dietary treatments Experimental design and procedures were reviewed and approved by the Institutional Animal Care and Use Committee at the University of Minnesota. This experiment was conducted at the University of Minnesota Southern Research and Outreach Center Swine Research Facility in Waseca, Minnesota, with 128 barrows weaned at 19 days of age (BW = 6.3 ± 1.4 kg) from Topigs females (Winnipeg, Manitoba; Landrace x Yorkshire) sired by Duroc boars (Compart’s Boar Store, Nicollet, MN). Sows were handled and fed according to the standard operating procedures of the research facility and fed common diets. Pigs were housed in pens (1.2 × 1.2 m; 4 pigs/pen), and each pen contained a dry feeder (3 feeder spaces) and a nipple drinker. Pigs were provided ad libitum access to water and experimental diets for 5 weeks. Pigs were stratified by BW into 8 blocks, assigned to one of 4 pens within block, and pens were assigned randomly to 1 of 4 dietary treatments within each block. Dietary treatments were fed in 3 phases (phase 1 = days 0–4, phase 2 = days 4–14, and phase 3 = days 14–35) and included: 90 g/kg unheated maize oil, 60 g/kg unheated maize oil +30 g/kg rapidly peroxidized (RO) maize oil, 30 g/kg unheated maize oil +60 g/kg RO maize oil, and 9 g/kg RO maize oil. Within each phase, diets were formulated to contain similar metabolizable energy (ME) and nutrient content except for the ratio of RO to unperoxidized maize oil. Consequently, all treatments contained the same ratio of standardized ileal digestible (SID) Lys to ME within phase. All diets were formulated to meet or exceed NRC (2012) requirements for nursery pigs fed diets containing 15.9 Mcal ME/kg for SID Lys, Met + Cys, Thr, Trp, total Ca, and apparent total tract digestible (ATTD) P. Diets were formulated to contain 16.9, 16.3, and 14.9 g/kg SID Lys; 4.4, 4.1, and 3.5 g/kg ATTD P; and provide Ca:ATTD P ratios of 2.2:1, 2.3:1, and 2.5:1 for phases 1–3, respectively. All diets were provided in meal form and contained Mecadox® 2.5 (carbadox 5.51 g/kg; Phibro Animal Health, Teaneck, NJ), which provided 27.5 mg/kg carbadox to the diets. Carbadox is commonly added to nursery pig diets to control enteric pathogens in the United States. Refined, deodorized, and bleached maize oil (Stratas Foods, Memphis, TN) was heated at 185 ◦ C for 12 h with a constant forced air flow rate of 12 L/min to yield RO maize oil. After heating, maize oil was stored in barrels in the feed mill for 2 days before making phase 1 diets. Mean daily outdoor temperature at the research facility during the experiment was 23.3 ± 4.1 ◦ C. Oil peroxide value (PV) was 1.7 and 5.7 meq/kg and thiobarbituric acid reactive substances (TBARS) content was 27.7 and 46.3 mg malondialdehyde (MDA) equiv./kg for unheated and RO maize oil, respectively. 2.2. Data and sample collection Pigs were weighed individually on days 0, 4, 14, and 35, and pen feed disappearance was recorded at the end of each dietary phase. These data were used to calculate average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and energetic efficiency (g ADG/MJ of ME intake) of each pen. In each pen, the pig closest to mean pen BW at day 0 was selected as the focal pig, and 20–30 mL blood (fed state) were collected via jugular venipuncture into vacutainer tubes coated with silicone (Becton Dickson, Franklin Lakes, NJ) on days 0, 14, and 35. Blood samples were allowed to clot at room temperature (5–10 min), stored at 4 ◦ C (≤6 h), and centrifuged (1400g for 10 min). Serum was transferred into microcentrifuge tubes and frozen at –80 ◦ C until further analysis. On day 35, focal pigs (n = 32) were euthanized by intravenous injection with sodium pentobarbital (>100 mg/kg BW). Intact livers and hearts

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

253

(without pericardium) were collected, weighed individually, and sampled. The heart somatic index and hepatosomatic index were calculated for each focal animal by the following formula:

 wetorganweight, g  BW, kg Samples of liver were snap frozen in liquid N, placed on dry ice, and stored at −80 ◦ C until further analysis. Hearts were evaluated visually by a veterinarian for pathological signs of Mulberry Heart Disease (MHD). Heart tissue was sampled and placed in solution of neutral buffered formalin (1:10 v/v). Heart sections were trimmed, embedded in paraffin, mounted onto slides, and stained with haematoxylin and eosin according to procedures described by Carson and Hladik (2005). A veterinary pathologist, blinded to treatments, evaluated heart sections histologically for lesions characteristic of MHD. 2.3. Laboratory analysis 2.3.1. Quality and peroxidation characteristics of maize oil Oil samples were retained during manufacture of phase 1 diets, frozen at –20 ◦ C, and analyzed for PV (method Cd 8-53; AOCS, 2013), TBARS, hexanal (Elisia and Kitts, 2011), moisture (method Ca 2c-25; AOCS, 2013), impurities (method Ca 3a-46; AOCS, 2013), and unsaponifiables (method Ca 6a-40; AOCS, 2013), free fatty acids (method Ca 5a-40; AOCS, 2013) and fatty acid profile (methods Ce 2-66; AOCS, 2013 and 996.06; AOAC, 2012) at the University of Missouri Agricultural Experiment Station Chemistry Laboratory. The TBARS assay was a modified version of the AOCS procedure (Cd 19-90; AOCS, 2013) with malonaldehyde used as a standard as described by Pegg (2001). Oxidative stability index at 110 ◦ C (method Cd 12b-92; AOCS, 2013)and P-anisidine value (method Cd 18-90; AOCS, 2013) were determined at Barrow-Agee Laboratory (Memphis, TN). 2.3.2. Dietary nutrient composition Feed samples were retained, frozen at –20 ◦ C, and analyzed for DM (method 930.15; AOAC, 2012), crude fat (method 920.39; AOAC, 2012), NDF (method 2002.04; AOAC, 2012, and Methods 5.1 and 5.2; NFTA, 1993), ADF, (method 973.18; AOAC, 2012 modified according to Tecator Application Note 3429), ash (method 942.05; AOAC, 2012), N (method 990.03; AOAC, 2012), Ca (method 985.01; AOAC, 2012), P (method 985.01; AOAC, 2012), S (method D4239; ASTM, 2011), Se, and vitamin E at Minnesota Valley Testing Laboratories (New Ulm). After digestion in nitric acid, Se was analyzed according to procedures described by Wahlen (2005) using an Agilent 7500ce Inductively Coupled Plasma Mass Spectrometer (Agilent Technologies Inc., Santa Clara, CA). The vitamin E content of feeds and maize oil was measured using a modified AOAC method (971.30; AOAC, 2012) with high-performance liquid chromatography (HPLC) and a fluorescence detector. A DLalpha tocopherol standard was used, and a conversion factor of 1.1 IU/kg was used to estimate total vitamin E content. Amino acids including Met, Cys, and Trp (method 982.30a,b,c; AOAC, 2012) were analyzed at the University of Missouri Agricultural Experiment Station Chemistry Laboratory (Columbia). 2.3.3. Liver and serum Se and ˛-tocopherol concentration In both experiments, Se and ␣-tocopherol concentrations in serum and liver samples were analyzed at the Michigan State University Diagnostic Center for Population and Animal Health (East Lansing). One gram of liver tissue was digested overnight in 2 mL nitric acid, and Se concentrations were determined according to the procedure of Wahlen (2005) using an Agilent 7500ce Inductively Coupled Plasma Mass Spectrometer (Agilent Technologies Inc., Santa Clara, CA). For ␣-tocopherol analysis, liver samples were weighed and homogenized in distilled, deionized water (1:4 w/v). Serum samples and liver homogenates were mixed with equal volumes of hexane and a solution of butylated hydroxytoluene in ethanol (1:10 w/v). Mixtures were centrifuged at 1900g for 10 min, and a known aliquot of the hexane layer was removed and dried under vacuum. Samples were dissolved in a chromatographic mobile phase (7:2:1, acetonitrile, methylene chloride, methanol) and analyzed by HPLC (Separation Module 2690) using a Waters Symmetry C18, 3.5 mm, 4.6 × 75 mm analytical column with detection by UV absorbency at 292 nm (Waters, Milford, MA). Trans-␤-APO-8 -carotenal was used as an internal standard. 2.3.4. Concentration of serum TBARS Serum was analyzed for TBARS concentration according to methods adapted from the Animal Models of Diabetic Complications Consortium (Feldman, 2004). Briefly, 100 ␮L serum samples and standards of malonaldehyde (catalog number: AC14861-1000, Fisher Scientific, Pittsburgh, PA) were mixed with 200 ␮L ice cold trichloroacetic acid (1:10, v/v; SigmaAldrich, St. Louis, MO) and centrifuged at 12,000g for 15 min at 4◦ C. Two hundred microliters of supernatant were removed and incubated with an equal volume of 0.67% (w/v) thiobarbituric acid (Sigma-Aldrich, St. Louis, MO) for 10 min in a dry block heater maintained at 100 ◦ C. Each vial was then cooled in an ice bath, and an aliquot was read at 532 nm using a spectrometer (SpectraMax 250, Molecular Devices, Sunnyvale, CA). 2.3.5. Concentration of serum triglycerides and cholesterol Commercial kits were used to evaluate serum samples for cholesterol (catalog number: C7509, Ponte Scientific, Inc., Canton, MI) and triglyceride content (catalog number: T7531, Ponte Scientific, Inc., Canton, MI). Two-microliters of serum or standards were combined in duplicate with 200 ␮L cholesterol or triglyceride reagents (pre-warm to 37 ◦ C), and incubated

254

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

at 37 ◦ C for 5 min. Cholesterol and triglycerides were measured using a spectrophotometer (SpectraMax 250, Molecular Devices, Sunnyvale, CA) at 520 nm and 540 nm, respectively, and concentrations were determined from standard curves. 2.3.6. Concentration of serum tryptophan Concentration of Trp was determined in serum at day 35 of the experiment by liquid chromatography–mass spectrometry (LC–MS). Briefly, 5 ␮L of samples or standards were mixed with 5 ␮L of 100 ␮M P-chlorophenylalanine (internal standard), 50 ␮L of 10 mM sodium carbonate, and 100 ␮L of dansyl chloride (3 mg/mL in acetone). The mixture was incubated at 25 ◦ C for 15 min and centrifuged (18,000g) for 10 min. Five microliters of supernatant were injected and separated in an Acquity BEH C18 column (Waters, Milford, MA) by a gradient of mobile phase ranging from water to 95% aqueous acetonitrile containing 0.1% formic acid for 10 min. The eluent was introduced into a SYNAPT quadrupole time-of-flight mass spectrometer (Waters, Milford, MA) for mass detection. Mass chromatograms and spectral data were acquired and processed by MassLynxTM software (Waters, Milford, MA) in centroid format. The concentration of Trp in serum was determined by calculating the ratio between Trp peak area and the peak area of P-chlorophenylalanine and fitting with a standard curve with a linear range from 5 ␮M to 250 ␮M using QuanLynxTM software (Waters, Milford, MA). 2.4. Statistical analyses The MIXED procedure of SAS (v9.3; SAS Inst. Inc., Cary, NC) was used to evaluate the main effect of diet, while block was a random effect. Linear, quadratic, and cubic orthogonal polynomial contrasts were used to compare dietary treatment means. For serum data, the repeated measures (unstructured variance) option was used to evaluate the effect of time (day 14 or 35) and its interaction with diet. For each serum variable, the value from weaning (day 0) was used as a covariate. Because ADFI varied across treatments, average daily intake of analyzed vitamin E or Se (overall daily feed intake × mean dietary concentration weighted by phase) were included as covariates when evaluating the concentration of ␣-tocopherol or Se, respectively, in serum and liver, and Trp intake was used as a covariate for Trp concentrations in serum. The dietary concentration (i.e. nutrient intake) of vitamin E (Chung et al., 1992; Lauridsen et al., 1999) Se (Kim and Mahan, 2001), and Trp (Le Floc’h et al., 2009) affects tissue and serum concentrations of these nutrients. The sum of triglyceride and cholesterol content of serum was a covariate for serum ␣-tocopherol analysis because concentrations of ␣-tocopherol are influenced by total serum lipids (Thurnham et al., 1986; Traber and Jialal, 2000). Pen was used as the experimental unit. Normality of model residuals was evaluated using the UNIVARIATE procedure of SAS. Results are reported as least squares means. Effects were deemed significant at P < 0.05, whereas values between 0.05 ≤ P ≤ 0.15 were considered trends. 3. Results One pig (90 g/kg unheated maize oil) died with signs of Clostridium infection. Regardless of treatment, pigs in all pens developed loose, gray stools after 1 week of treatment. This condition remained in the majority of pens throughout the experiment, and may have been related to the high lipid content of the experimental diets. No other signs of illness were apparent, and no pigs displayed pathological or histopathological lesions of MHD. Diets containing RO maize oil had reduced analyzed concentrations of vitamin E compared with diets without RO, and these differences were greater in magnitude for phase 3 compared with phase 1 diets (Table 1). However, the analyzed vitamin E content of RO maize oil was only 15.9% less than unheated maize oil (Table 2). The PV, TBARS, p-Anisidine value, hexanal, and free fatty acid content of RO maize oil were substantially greater than unheated maize oil (Tables 2). 3.1. Growth performance During phase 1, ADG, G:F, and energetic efficiency declined linearly (P < 0.05) with increasing concentrations of RO maize oil (Table 3). Consequently, BW on day 4 declined linearly (P ≤ 0.01) with increased RO maize oil content (mean = 6.6, 6.5, 6.4, and 6.3 ± 0.2 kg, for 0, 30, 60, or 90 g/kg RO maize oil, respectively). During phase 3, ADG (P < 0.15), ADFI (P < 0.15), and caloric intake (P < 0.15) tended to decline linearly with increasing dietary RO maize oil content, but G:F was not affected (Table 3). Final BW (day 35) tended to decline linearly with increasing dietary RO maize oil concentration (P < 0.15), coinciding with a linear reduction in ADG (P < 0.15), G:F (P < 0.05), and energetic efficiency (P < 0.05; data not shown) measured over the 35-day feeding period (Table 3). 3.2. Metabolic peroxidation indicators Intake of vitamin E declined (linear, quadratic, and cubic; P < 0.01) and Se changed quadratically (P ≤ 0.05) with increased dietary RO maize oil content (Table 4). The heart somatic index and hepatosomatic index, as well as the ␣-tocopherol and Se concentrations of liver, were not affected by dietary treatment (Table 4). The Trp concentration of serum tended to decline linearly with increased dietary RO maize oil content (P < 0.15; Table 4). The mean days 14–35 concentration of ␣-tocopherol in serum declined (linear, cubic; P < 0.01) with increased dietary RO maize oil content, but there was a diet × day interaction (P < 0.05; Table 5). The ␣-tocopherol concentration of serum declined on day 14 (linear, P < 0.01) and day 35 (linear and cubic P ≤ 0.01) with increased RO maize oil in the diet. The mean day 14 to 35 Se concentration of serum tended to decline linearly

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

255

Table 1 Composition of experimental diets (as-fed basis). Phase 1 (weaning to day 4)1 2

Phase 2 (day 4–14)

Phase 3 (day 14–35)

Item

0

30

60

90

0

30

60

90

0

30

60

90

Ingredient, g/kg Maize Soybean meal, 475 g/kg CP Peroxidized maize oil2 Unperoxidized maize oil3 Fish meal Dried whey Lactose Spray dried porcine plasma Antibiotic4 Zinc oxide Vitamin/mineral premix5 L-Lys DL-Met L-Thr Dicalcium phosphate Limestone Salt

272.0 229.1 0.0 90.0 90.0 100.0 129.1 50.0 5.0 5.0 5.0 3.8 2.2 1.4 2.1 10.2 5.1

272.0 229.1 30.0 60.0 90.0 100.0 129.1 50.0 5.0 5.0 5.0 3.8 2.2 1.4 2.1 10.2 5.1

272.0 229.1 60.0 30.0 90.0 100.0 129.1 50.0 5.0 5.0 5.0 3.8 2.2 1.4 2.1 10.2 5.1

272.0 229.1 90.0 0.0 90.0 100.0 129.1 50.0 5.0 5.0 5.0 3.8 2.2 1.4 2.1 10.2 5.1

360.1 318.9 0.0 90.0 80.0 109.8 0.0 0.0 5.0 5.0 5.0 4.0 2.2 1.4 3.5 8.7 6.5

360.1 318.9 30.0 60.0 80.0 109.8 0.0 0.0 5.0 5.0 5.0 4.0 2.2 1.4 3.5 8.7 6.5

360.1 318.9 60.0 30.0 80.0 109.8 0.0 0.0 5.0 5.0 5.0 4.0 2.2 1.4 3.5 8.7 6.5

360.1 318.9 90.0 0.0 80.0 109.8 0.0 0.0 5.0 5.0 5.0 4.0 2.2 1.4 3.5 8.7 6.5

488.2 370.1 0.0 90.0 0.0 0.0 0.0 0.0 5.0 0.0 5.0 5.4 2.4 1.8 15.1 8.9 8.2

488.2 370.1 30.0 60.0 0.0 0.0 0.0 0.0 5.0 0.0 5.0 5.4 2.4 1.8 15.1 8.9 8.2

488.2 370.1 60.0 30.0 0.0 0.0 0.0 0.0 5.0 0.0 5.0 5.4 2.4 1.8 15.1 8.9 8.2

488.2 370.1 90.0 0.0 0.0 0.0 0.0 0.0 5.0 0.0 5.0 5.4 2.4 1.8 15.1 8.9 8.2

Analyzed composition Metabolizable energy (ME), MJ/kg6 Crude protein, g/kg Crude fat, g/kg Ca, g/kg P, g/kg Se mg/kg Vitamin E, IU/kg Lys, g/kg Met + Cys, g/kg Thr, g/kg Trp, g/kg

15.8 231 103.0 11.7 7.1 0.73 47.4 18.3 9.8 10.4 3.0

15.8 224 112.5 11.4 6.9 0.69 42.0 17.7 9.5 10.5 3.0

15.8 234 105.6 10.4 6.8 0.72 41.5 18.0 9.7 10.5 3.0

15.8 227 111.1 11.0 6.9 0.68 40.2 18.5 9.7 10.5 3.1

15.6 249 108.6 10.8 7.0 0.63 44.3 17.7 10.0 10.7 3.0

15.6 249 122.4 10.7 6.8 0.79 43.0 17.3 8.2 9.8 2.9

15.6 242 108.9 12.2 7.3 0.77 38.3 18.0 8.9 9.6 3.0

15.6 248 105.6 10.8 7.0 0.68 27.9 17.4 8.9 9.6 3.2

15.4 215 115.9 8.5 6.6 0.63 50.7 17.0 8.6 10.1 2.7

15.4 201 97.6 8.5 6.7 0.57 26.9 18.3 8.9 9.1 2.6

15.4 226 120.9 11.2 7.6 0.64 29.3 17.7 8.2 9.5 3.0

15.4 226 103.6 9.5 7.0 0.63 26.4 17.1 8.7 9.1 2.8

Pigs were weaned at approximately 19 days of age; BW = 6.3 ± 1.4 kg. Diets contained either 0, 30, 60, or 90 g/kg of maize oil that had been heated for 12 h at 185 ◦ C with a constant forced air flow rate of 12 L/min and resulting peroxide value = 5.7 meq O2 /kg and TBARS = 26.7 mg MDA eq/g. 3 Unperoxidized maize oil was not subjected to heat treatment and had a peroxide value = 1.7 meq O2 /kg and TBARS = 48.3 mg MDA eq/kg. 4 Mecadox® 2.5 (carbadox 5.51 g/kg; Phibro Animal Health, Teaneck, NJ) provided 27.5 mg carbadox per kg of diet. 5 Premix supplied the following nutrients per kilogram of diet: 11,023 IU of vitamin A as retinyl acetate; 2756 IU of vitamin D3 ; 22 IU of vitamin E as dl-alpha tocopheryl acetate; 4.41 mg of vitamin K as menadione dimethylpyrimidinol bisulfite; 9.92 mg of riboflavin; 55.11 mg of niacin; 33.07 mg of pantothenic acid as d-calcium pantothenate; 992 mg of choline as choline chloride; 0.06 mg of vitamin B12 ; 14.3 mg of pyridoxine; 1.65 mg of folic acid; 2.20 mg of thiamine; 0.33 mg of biotin; 2.20 mg of iodine as ethylenediamine dihydroiodide; 0.30 mg of selenium as sodium selenite; 299 mg of zinc as zinc sulfate; 299 mg of iron as ferrous sulfate; 19.8 mg of copper as copper sulfate; and 17.6 mg of manganese as manganese oxide. 6 ME values were calculated using NRC (2012) values. 1 2

(P ≤ 0.10) with increased dietary RO maize oil content (Table 5). The serum concentration of ␣-tocopherol and Se declined (P < 0.01) from day 14 to 35, while the concentration of TBARS tended to increase (P ≤ 0.10) linearly when feeding increasing levels of RO maize oil (Table 5). The serum concentration of ␣-tocopherol and Se declined (P < 0.01) from day 14 to 35, while the concentration of cholesterol (P ≤ 0.10) and triglycerides (P ≤ 0.10) tended to decline linearly when feeding increasing levels of RO maize oil (Table 5). 4. Discussion 4.1. Growth performance Understanding the peroxidative status of dietary lipids is of critical importance for nutritionists to minimize negative consequences to animal health and growth performance. Dietary inclusion of peroxidized fats (DeRouchey et al., 2004) and oils (Harrell et al., 2010; Boler et al., 2012; Liu et al., 2014a) reduces growth performance of pigs. Similar responses have been reported in broilers (Tavárez et al., 2011). In addition, researchers have reported that lipid peroxidation contributes to cellular inefficiencies and damage which can affect the functionality of proteins and DNA at the metabolic level (Yu, 1994), and consequently reduce the growth performance and health of animals (Lykkesfeldt and Svendsen, 2007). Dibner et al. (1996) reported that feeding peroxidized lipids to broilers increased turnover of the gastrointestinal tract epithelium resulting in reduced nutrient uptake and increased energy expenditure. Some researchers have suggested that the reduction in growth rate in pigs observed when feeding peroxidized lipids is simply a result of a reduction in feed and nutrient feed intake. Dietary peroxidized lipids often reduce ADFI when replacing

256

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

Table 2 Characteristics of maize oil used in experimental diets1 .

1

Item

Unox

RO

Peroxide value, meq/kg TBARS, mg MDA eq/kg p-Anisidine value Hexanal, ␮g/g OSI, h Vitamin E, IU/100 g Free fatty acids, g/kg Moisture, g/kg Impurities, g/kg Unsaponifiables, g/kg

1.66 27.70 5.32 1.49 10.75 27.70 2.6 1.9 <0.5 17.2

5.71 46.30 138.00 5.93 2.15 23.30 5.30 1.70 <0.50 14.90

Fatty acids, g/kg of ether extract C14:0 C14:1 C15:0 C16:0 C16:1 C18:0 C18:1 C18:2 C18:3 Unsaturated/saturated ratio

0.30 0 0 115 1 10 298 539 9.6 6.7

<0.01 0 0 112 1 20 274 489 6.6 6.0

Unox = maize oil was not subjected to heat treatment and RO = maize oil heated at 185 ◦ C for 12 h with air flow rate of 12 L/min.

Table 3 Growth performance of pigs fed increasing dietary concentrations of rapidly peroxidized maize oil. Level of peroxidized maize oil1 , g/kg Item Phase 1 (d0-4) ADG, g ADFI, g Gain:feed Energy intake, MJ ME/d3 Phase 2 (d4-14) ADG, g ADFI, g Gain:feed Energy intake, MJ ME/d Phase 3 (d14-35) ADG, g ADFI, g Gain:feed Energy intake, MJ ME/d Overall (d 0–35) Initial wt., kg Final BW, kg ADG, g ADFI, g Gain:feed Energy intake, MJ ME/d

P-values 2

0

30

60

90

PSEM

Linear

Quadratic

Cubic

71.6 87.9 0.80 1.38

56.7 88.2 0.50 1.38

13.8 83.3 0.04 1.34

−5.3 70.2 −1.17 1.13

23.41 10.59 0.63 0.17

0.01 0.20 0.03 0.20

0.92 0.50 0.50 0.50

0.58 0.95 0.90 0.95

330.1 405 0.82 6.32

355.9 438 0.81 6.86

360.6 447.1 0.81 6.99

344.7 429.4 0.8 6.69

20.11 23.4 0.03 0.38

0.52 0.38 0.64 0.38

0.22 0.23 0.82 0.23

0.99 0.98 0.91 0.98

458.5 653.7 0.70 10.08

446 647.2 0.69 10.00

441.3 645 0.68 9.96

415.2 601.5 0.69 9.29

17.17 20.95 0.01 0.33

0.07 0.10 0.43 0.10

0.67 0.38 0.41 0.38

0.68 0.63 0.97 0.63

6.3 19.5 377.5 515.3 0.73 8.16

6.3 19.5 375.8 523.6 0.72 8.28

6.3 19.2 369.4 524.3 0.70 8.33

6.3 18.5 347 491.6 0.71 7.78

0.23 0.59 13.62 16.81 0.01 0.25

0.32 0.11 0.10 0.35 0.03 0.35

0.91 0.44 0.43 0.23 0.34 0.23

0.87 0.85 0.84 0.73 0.79 0.73

1 Peroxidized maize oil was heated for 12 h at 185 ◦ C with a constant forced air flow rate of 12 L/min. Unperoxidized maize oil was added so all diets contained 90 g supplemental maize oil per kg of diet. 2 PSEM = pooled standard error of means, n = 8 observations/treatment. 3 ME = metabolizable energy.

fresh lipids in swine diets (DeRouchey et al., 2004; Yuan et al., 2007; Harrell et al., 2010; Boler et al., 2012; Liu et al., 2014b), which may be due to the “rancid” flavor of compounds produced during peroxidation (Belitz et al., 2009). In the present experiment, overall feed intake was not affected by RO maize oil, but there was a tendency for a reduction in ADFI with increasing RO maize oil from day 14 to 35. However, overall ADG declined with increasing dietary RO maize oil content. Our results suggest the performance of pigs was affected more by dietary RO maize oil content during the initial 4-day post-weaning than the subsequent 10 day period. Both ADG and gain:feed decreased considerably with increasing dietary RO maize oil content from day 0 to day 4, but effects were absent during the subsequent 10-day period. Regardless of dietary treatment, serum concentrations of ␣-tocopherol declined from 5.9 ug/mL at weaning, to 0.93 ug/mL on day 14 post-weaning. Other researchers have reported that circulating levels of vitamin E decline within the first few weeks post-weaning (Chung et al., 1992; Moreira and Mahan, 2002; Lauridsen, 2010). The metabolic oxidative system of pigs is clearly stressed during

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

257

Table 4 Selected tissue parameters of pigs fed increasing dietary concentrations of rapidly peroxidized maize oil. Level of peroxidized maize oil1 , g/kg

P-values 2

Item

0

30

60

90

PSEM

Linear

Quadratic

Cubic

Average daily vitamin E intake, IU3 Average daily Se intake, mg3 Heart somatic index, g/kg4 Liver Hepatosomatic index, g/kg5 ␣-Tocopherol, ug/g, wet wt.6 Selenium, ug/g, wet wt.6 Serum: Trp, uM6,7

24.99 0.33 5.3

17.38 0.34 5.3

17.44 0.36 5.2

13.95 0.32 5.9

0.65 0.01 0.30

<0.01 0.80 0.24

<0.01 0.05 0.24

<0.01 0.13 0.4

33.3 2.34 0.57

34.4 2.65 0.57

34.1 2.70 0.59

35.1 3.14 0.58

1.4 0.49 0.02

0.38 0.50 0.58

0.97 0.87 0.80

0.63 0.73 0.48

53.08

39.45

44.18

40.95

0.05

0.08

0.20

0.14

Maize oil was heated for 12 h at 185 ◦ C with a constant forced air flow rate of 12 L/min. Unperoxidized maize oil was added so all diets contained 90 g supplemental maize oil per kg of diet. 2 PSEM = pooled standard error of means, n = 8 observations/treatment. 3 Mean analyzed dietary content weighted by phase length × overall ADFI. 4 (Heart weight, g/BW, kg). 5 (Liver weight, g/BW, kg). 6 Average daily intake of vitamin E (P > 0.1), Se (P > 0.1), or Trp (P = 0.1) were used as covariates for each respective measure. 7 Serum collected at day 35 of experiment. 1

Table 5 Metabolites in serum from pigs fed increasing dietary concentrations of rapidly peroxidized maize oil. Level of peroxidized maize oil1 , g/kg Item

0

Serum ␣-tocopherol, ug/mL3 Day 14 1.40 0.58 Day 35 Mean (days 14 and 35) 0.99 Serum selenium, ng/mL4 Day 14 114.38 Day 35 130.38 122.38 Mean (days 14 and 35) Serum TBARS, uM5 Day 14 0.76 Day 35 0.82 Mean (days 14 and 35) 0.79 6 Serum cholesterol, ug/dL Day 14 1070.02 837.22 Day 35 953.62 Mean (days 14 and 35) Serum triglycerides, ug/dL7 Day 14 269.19 Day 35 329.38 297.06 Mean (days 14 and 35)

30

P-values 2

60

90

PSEM

0.91 0.28 0.59

0.89 0.30 0.59

0.49 0.13 0.31

0.06 0.08 0.08

113.62 131.37 122.50

103.06 130.93 117.00

106.19 118.06 112.13

7.05 7.05 5.10

0.83 0.83 0.83

0.81 0.82 0.81

0.88 0.83 0.85

0.05 0.05 0.02

1086.21 684.56 885.38

970.42 880.28 925.35

689.52 541.14 615.33

74.07 74.07 65.71

234.37 273.30 252.67

211.88 271.68 239.03

220.00 173.72 194.79

44.71 44.71 37.85

Day

<0.01

0.37

0.99

0.37

0.99

Diet × day

Linear

Quadratic

Cubic

0.03

<0.01 <0.01 <0.01

0.64 0.07 0.32

0.07 0.01 0.01

<0.01

0.19 0.28 0.10

0.76 0.39 0.64

0.39 0.76 0.74

0.85

0.13 0.89 0.06

1.00 1.00 1.00

0.36 0.86 0.22

<0.01

0.19 0.28 0.10

0.76 0.39 0.64

0.39 0.76 0.74

0.85

0.13 0.89 0.06

1.00 1.00 1.00

0.36 0.86 0.22

Maize oil was heated for 12 h at 185 ◦ C with a constant forced air flow rate of 12 L/min. Unperoxidized maize oil was added so all diets contained 90 g supplemental maize oil per kg of diet. 2 PSEM = pooled standard error of means, n = 8 observations/treatment. 3 Data were covariate adjusted for concentration at weaning (mean = 5.9 ± 0.5 ug/mL; P = 0.01), intake of vitamin E (P < 0.01), and serum lipids content (P = 0.13). 4 Data were covariate adjusted for concentration at weaning, mean = 128.1 ± 3.7 ng/mL (P > 0.1) and intake of Se (P > 0.1). 5 Data were covariate adjusted for concentration at weaning, mean = 0.83 ± 0.07 uM (P > 0.1). 6 Data were covariate adjusted for concentration at weaning, mean = 2,734.8 ± 305.6 ug/dL (P > 0.1). 7 Data were covariate adjusted for concentration at weaning, mean = 373.3 ± 67.2 ug/dL (P > 0.05). 1

the post-weaning transition, which may increase sensitivity of young pigs to peroxidized lipids. Efficiency of gain declined 2.7–4.1% for pigs fed diets with 60–90 g/kg RO maize oil compared with pigs fed similar diets with unperoxidized maize oil, but gain efficiency declined only 1.4% for pigs fed 30 g/kg RO maize oil compared with those fed diets with unheated maize oil. These results indicate that weaned pigs are most sensitive to peroxidized maize oil during the first 4 days postweaning, and growth performance is linearly reduced when feeding diets with increasing concentrations of peroxidized maize oil. Diets were formulated to be identical, with the only difference being the ratio of unperoxidized to peroxidized maize oil. These findings indicate that RO maize oil may have a reduced energy value compared with unperoxidized maize oil. Other researchers have found reduced gain efficiency when feeding peroxidized lipids to broilers (McGill et al., 2011a,b; Tavárez et al., 2011) and swine (DeRouchey et al., 2004), but caloric efficiency was not reported. Our findings indicate that peroxidation reduces the energy value of maize oil. A reduction in energy value may relate to the negative metabolic effects

258

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

of compounds produced during peroxidation and the presence of these peroxidation compounds (e.g. polymers) impaired the conversion of lipids to energy by the animal (Wiseman, 2003). Some researchers have suggested that peroxidized lipids impair nutrient digestibility and energy value (Engberg et al., 1996; Yuan et al., 2007). However, others have reported that the metabolizable energy value of lipids is not influenced by peroxidation (DeRouchey et al., 2004; Liu et al., 2014a). Lipid peroxidation is a complex process that produces numerous compounds which degrade antioxidants, alter diet flavor, and influence health and metabolic oxidative status of animals (Lykkesfeldt and Svendsen, 2007; Belitz et al., 2009). In addition, the relative concentrations of peroxidation products are influenced by lipid composition as well as temperature and duration of thermal conditions lipids are exposed to during peroxidation (Liu et al., 2014b). Historically, PV has been used commonly to indicate lipid peroxidation. While the PV of the RO maize oil was 3.5 fold greater than unheated maize oil, the PV of RO maize oil subjected to similar thermal conditions was similar to unheated oil reported by Liu et al., 2014c. Due to the rapid increase in initial peroxidation compounds measured by PV, followed by a rapid decomposition of these peroxidation products as thermal treatment continues, suggests that the use of PV as a sole indicator of lipid peroxidation can provide inaccurate and misleading results of the extent of peroxidation of lipids. Peroxides and aldehydes that are initially produced during the peroxidation process are subsequently degraded resulting in a bell shaped curve of concentration over time (Fitch ´ Haumann, 1993; DeRouchey et al., 2004; Danowska-Oziewicz and Karpinska-Tymoszczyk, 2005). Therefore, measures such as PV, anisidine value, and TBARS may be misleadingly low in lipids subjected to high temperatures for an extended period ´ 2005). As a result, some researchers have suggested that PV has of time (Danowska-Oziewicz and Karpinska-Tymoszczyk, limited utility for lipids subjected to temperatures exceeding 150◦ C (Shahidi and Zhong, 2005). Although PV is not a reliable indicator of peroxidation, it has been used extensively to evaluate lipid quality in the feed industry. As a result, some researchers have suggested maximum tolerable levels of for PV as an indicator of extent of peroxidation of lipids in swine diets. DeRouchey et al. (2004), Azain (2001), and Gray and Robinson (1941) suggested maximal threshold levels for PV of 2.4 meq O2 /kg diet, 5 meq O2 /kg lipid and 20 meq O2 /kg lipid, respectively, but these recommendations are not supported by the current experiment. In the current experiment, feeding diets with PV (≤0.51 meq O2 /kg diet or 5.7 meq O2 /kg oil) below the threshold levels recommended by others, reduced ADG by as much as 8.1% without impacting ADFI, and led to a 2.7% reduction in G:F relative to pigs fed unperoxidized maize oil. Our results further indicate that PV is a poor predictor of lipid quality for pigs fed diets with lipids peroxidized by exposure to elevated temperatures. Consequently, more appropriate measures of lipid peroxidation, or combinations thereof, must be identified to facilitate determination of the maximum tolerable limits of peroxidized lipids in diets for swine. Liu (2012) reported that ADG tended to be negatively associated (r = − 0.29, P = 0.09) with TBARS content of dietary lipids. Both TBARS and hexanal content of RO maize oil (46.3 mg MDA eq/kg and 5.93 ␮g/g) were elevated relative to unperoxidized maize oil (27.7 mg MDA eq/kg and 1.49 ␮g/g). However, maximal levels of these indicators have not been established. DeRouchey et al. (2004) suggested that feeding lipids with p-anisidine values of 10.6 will not impair performance of nursery pigs, and the p-anisidine value of the peroxidized maize oil used in the current experiment was 138. Future investigators are encouraged to report results of several peroxidation indicators to provide more comprehensive analyses of the extent of peroxidation of lipids fed relative to growth performance responses observed. Doing so will facilitate the development suitable indicators of lipid quality and maximal tolerable thresholds of peroxidized lipids in swine diets. 4.2. Metabolic oxidation measures The hepatosomatic index serves as a biological indicator of toxicity (Juberg et al., 2006). Other researchers have demonstrated that feeding diets containing peroxidized lipids increased liver size (Huang et al., 1988; Eder, 1999; Liu, 2012), and this phenomenon may relate to increased synthesis of microsomal enzymes to mitigate toxicity (Huang et al., 1988; Liu et al., 2014b). The reason that the hepatosomatic index was not affected by dietary RO maize oil concentration in the present study is unclear. The rapid peroxidation treatment used in this experiment partially degraded the indigenous vitamin E in maize oil, which has also been reported in other studies (Seppanen and Csallany, 2002; Liu et al., 2014c). However, the differences vitamin E content among diets were greater in magnitude for phase 3 (as much as 48% reduction) compared with phase 1 (as much as 16% reduction). While the analyzed vitamin E content of RO maize oil was 15.9% less than unheated maize oil, this sample was obtained at the beginning of the experiment. Maize oil was not sampled and analyzed at the end of the feeding period. Other studies have shown that the vitamin E content declines to undetectable levels after heating (Seppanen and Csallany, 2002; Liu et al., 2014c). Therefore, the reduction in magnitude of change in vitamin E content the current experiment may have been related to the fact that oil was sampled before extended storage, and the increased magnitude of reduction of dietary vitamin E content for phase 3 relative to phase 1 may have resulted from further peroxidation during storage because of the increased level of reactive products in the RO maize oil. Consequently, the daily intake of vitamin E was dissimilar among dietary treatments. Therefore, vitamin E intake was used as a covariate in statistical analysis of serum and liver vitamin E. Several studies have shown that feeding peroxidized lipids reduces the vitamin E content in serum or liver (Liu and Huang, 1995; Boler et al., 2012; Liu et al., 2014b), which may be related to reduced vitamin E intake or increased metabolic demand for vitamin E. However, we did not observe substantial effects of feeding peroxidized maize oil on the concentration of vitamin E or Se in liver. Generally, liver concentrations <2 ␮g ␣-tocopherol/g are considered deficient (Rice and Kennedy, 1989), but mean values did not fall below this threshold in the current experiment. As a result, feeding peroxidized maize oil did not contribute to the development of MHD in the current

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

259

experiment. Perhaps if diets were fed for an extended duration (i.e. >5 weeks), changes in vitamin E or Se concentrations would have been detected in the liver. However, the concentration of TBARS in serum is indicative of metabolic oxidative stress (Kerr et al., 2015). Concentration of TBARS tended to increase, while vitamin E declined in serum of pigs fed diets with increasing dietary RO maize oil. Therefore, our data suggest that metabolic oxidative stress occurs when feeding peroxidized maize oil to nursery pigs, but not to the extent that they develop MHD. Weaned pigs are highly susceptible to oxidative stress, which may contribute to antioxidant deficiencies to lead to MHD during the initial weeks post-weaning (Ullrey, 1981). However, no signs of MHD were observed in this experiment. Pallarés et al. (2002) suggested that additional factors predispose pigs to developing MHD such as stress, genetics, and pathogenic infections. However, no known pathogenic challenges were observed and environmental stressors were minimal in the current study. Peroxidized maize oil did not affect the Se content of liver, but there was a tendency for a linear reduction in Se content of serum with peroxidized oil. However, comparable data in the literature are lacking. Upton et al. (2009) reported that feeding peroxidized lipids increases glutathione peroxidase activity of broilers (Upton et al., 2009), which is a selenoenzyme. Other researchers have reported that genes regulating antioxidant enzymes are upregulated for swine in response to peroxidized lipids (Varady et al., 2012). However, enzyme activity was not assessed in the current trial. Increasing dietary levels of peroxidized maize oil reduced the concentration of Trp in serum linearly, and this finding has been reported by others (Liu, 2012) in pigs. A recent study with rodents (Wang et al., 2012) suggested that metabolites of the kynurenine pathway (e.g. kyneurenic acid and nicotinamide N-oxide) are up-regulated in response to feeding peroxidized soybean oil. However, the practical significance of this finding is not immediately apparent, and it is unclear if elevated catabolism of Trp reduces the amount available for protein synthesis. In addition to the roles in the synthesis of muscle protein and neurotransmitters (Wu, 2009), Trp is incorporated into acute phase proteins (Reeds et al., 1994). Consequently, some researchers have suggested that pigs benefit from increased dietary Trp in response to stress (Kim et al., 2010; Shen et al., 2012), and suggest that Trp requirements may depend on stressors such as cleanliness of the rearing environment (Le Floc’h et al., 2009). However, no research has been conducted to determine if animals fed dietary peroxidized lipids respond to increased dietary concentrations of Trp. Many metabolites of Trp in both the kynurenine and indole pathways act as antioxidants (Goda et al., 1999; Wu, 2009), and Trp is a precursor of niacin, which is used to generate nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate that are used as reducing agents in oxidative defense. In summary, feeding peroxidized maize oil negatively affected energetic efficiency of nursery pigs and growth of nursery pigs. Our results suggest that PV is a poor indicator of lipid peroxidation, and that markers such as TBARS, p-anisidine value, and hexanal should be further investigated for practical use. In both experiments, feeding peroxidized maize oil reduced the vitamin E content and increased TBARS of serum, but Mulberry Heart Disease was not detected. Further studies should evaluate whether adding antioxidants can alleviate some of the negative effects of peroxidized lipid on growth performance and efficiency. 5. Conclusions Weaned pigs appear to be most susceptible to feeding diets containing peroxidized maize oil during the first 4 days post-weaning, and increasing dietary peroxidized maize oil from 0 to 90 g/kg for nursery pigs tended to linearly reduce ADG and final BW (day 35), and reduced G:F linearly during the 35 day nursery period. However, growth performance of pigs fed diets with peroxidized maize oil at 30 g/kg was minimally affected compared with that of pigs fed similar diets with unheated lipid. With increasing levels of peroxidized maize oil, serum ␣-tocopherol content declined and concentration of TBARS increased. These results indicate that peroxidized maize oil may negatively affect growth performance, efficiency, and metabolic oxidative balance of weaned pigs. Conflict of interest All authors declare that we have no actual or potential conflict of interest including any financial, personal, or other relationships that could inappropriately influence, or be perceived to influence this work Acknowledgements Funding for this research was partially supported by the Minnesota Pork Board and Minnesota Corn Research and Promotion Council. We thank Drs. N. Macedo and N. Homowong (College of Veterinary Medicine, University of Minnesota) for examination of heart tissue. References AOAC, 2012. Official Methods of Analysis. AOAC, Intl., Gaithersburg, MD. American Oil Chemists’ Society (AOCS), 2013. Official Methods and Practices of the AOCS. AOCS, Champaign, IL. ASTM (American Society for Testing and Materials), 2011. D4239: Standard Test Method for Sulfur in the Analysis Sample of Coal and Coke Using High-temperature Tube Furnace Combustion. ASTM, West Conshohocken, PA. Azain, M.J., 2001. Fat in swine nutrition. In: Lewis, A.J., Southern, L.L. (Eds.), Swine Nutrition. CRC Press, Boca Raton, pp. 95–106. Belitz, H.D., Grosch, W., Schieberle, P., 2009. Lipids. In: Belitz, H.D., Grosch, W., Schieberle, P. (Eds.), Food Chemistry. Springer, Berlin, pp. 158–247.

260

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

˜ Boler, D., Fernández-Duenas, D., Kutzler, L., Zhao, J., Harrell, R., Campion, D., McKeith, F., Killefer, J., Dilger, A., 2012. Effects of oxidized corn oil and a synthetic antioxidant blend on performance, oxidative status of tissues, and fresh meat quality in finishing barrows. J. Anim. Sci. 90, 5159–5169. Carson, F.L., Hladik, C., 2005. Histotechnology: A Self-instructional Text. American Society for Clinical Pathology Press, Chicago. Chung, Y., Mahan, D., Lepine, A., 1992. Efficacy of dietary d-alpha-tocopherol and dl-alpha-tocopheryl acetate for weanling pigs. J. Anim. Sci. 70, 2485–2492. ´ Danowska-Oziewicz, M., Karpinska-Tymoszczyk, M., 2005. Quality changes in selected frying fats during heating in a model system. J. Food Lipids 12, 159–168. DeRouchey, J., Hancock, J., Hines, R., Maloney, C., Lee, D., Cao, H., Dean, D., Park, J., 2004. Effects of rancidity and free fatty acids in choice white grease on growth performance and nutrient digestibility in weanling pigs. J. Anim. Sci. 82, 2937–2944. Dibner, J., Atwell, C., Kitchell, M., Shermer, W., Ivey, F., 1996. Feeding of oxidized fats to broilers and swine: effects on enterocyte turnover, hepatocyte proliferation and the gut associated lymphoid tissue. Anim. Feed Sci. Technol. 62, 1–13. Dibner, J., Vazquez-Anon, M., Knight, C., 2011. Understanding oxidative balance and its impact on animal performance. In: Proceedings 2011 Cornell Nutrition Conference for Feed Manufacturers, East Syracuse, NY, pp. 1–7. Eder, K., 1999. The effects of a dietary oxidized oil on lipid metabolism in rats. Lipids 34, 717–725. Elisia, I., Kitts, D.D., 2011. Quantification of hexanal as an index of lipid oxidation in human milk and association with antioxidant components. J. Clin. Biochem. Nutr. 49, 147–152. Engberg, R.M., Lauridsen, C., Jensen, S.K., Jakobsen, K., 1996. Inclusion of oxidized vegetable oil in broiler diets. Its influence on nutrient balance and on the antioxidative status of broilers. Poult. Sci. 75, 1003–1011. E., Feldman, 2004. Thiobarbituric acid reactive substances (TBARS) assay. Pages 1–3 in AMDCC Protocols, Version 1. pp. 1–3. Fitch Haumann, B., 1993. Lipid oxidation: health implications of lipid oxidation. Inform 4, 800–819. Goda, K., Hamane, Y., Kishimoto, R., Ogishi, Y., 1999. Radical Scavenging Properties of Tryptophan Metabolites, Tryptophan, Serotonin, and Melatonin. Springer, pp. 397–402. Gray, R., Robinson, H., 1941. Free fatty acids and rancidity in relation to animal by-product protein concentrates. Poult. Sci. 20, 36–41. Gutteridge, J., 1995. Lipid peroxidation and antioxidants as biomarkers of tissue damage. Clin. Chem. 41, 1819–1828. Harrell, R.J., Zhao, J., Reznik, G., Macaraeg, D., Wineman, T., Richards, J., Rexnik, G., 2010. Application of a blend of dietary antioxidants in nursery pigs fed either fresh or oxidized corn oil or DDGS. J. Anim. Sci., 60. Huang, C.J., Cheung, N.S., Lu, V.R., 1988. Effects of deteriorated frying oil and dietary protein levels on liver microsomal enzymes in rats. J. Am. Oil Chem. Soc. 65, 1796–1803. Juberg, D.R., Mudra, D.R., Hazelton, G.A., Parkinson, A., 2006. The effect of fenbuconazole on cell proliferation and enzyme induction in the liver of female CD1 mice. Toxicol. Appl. Pharmacol. 214, 178–187. Kerr, B.J., Kellner, T.A., Shurson, G.C., 2015. Characteristics of lipids and their feeding value in swine diets. J. Anim. Sci. Biotechnol. 6, 30. Kim, Y.Y., Mahan, D.C., 2001. Effects of high dietary levels of selenium-enriched yeast and sodium selenite on macro and micro mineral metabolism in grower-finisher swine. Asian-Australas. J. Anim. Sci. 14, 243–249. Kim, C.J., Kovacs-Nolan, J.A., Yang, C., Archbold, T., Fan, M.Z., Mine, Y., 2010. l-Tryptophan exhibits therapeutic function in a porcine model of dextran sodium sulfate (DSS)-induced colitis. J. Nutr. Biochem. 21, 468–475. Lauridsen, C., Højsgaard, S., Sørensen, M.T., 1999. Influence of dietary rapeseed oil, vitamin E, and copper on the performance and the antioxidative and oxidative status of pigs. J. Anim. Sci. 77, 906–916. Lauridsen, C., 2010. Evaluation of the effect of increasing dietary vitamin E in combination with different fat sources on performance, humoral immune responses and antioxidant status of weaned pigs. Anim. Feed Sci. Technol. 158, 85–94. Le Floc’h, N., LeBellego, L., Matte, J., Melchior, D., Sève, B., 2009. The effect of sanitary status degradation and dietary tryptophan content on growth rate and tryptophan metabolism in weaning pigs. J. Anim. Sci. 87, 1686–1694. Liu, J.F., Huang, C.J., 1995. Tissue alpha-tocopherol retention in male rats is compromised by feeding diets containing oxidized frying oil. J. Nutr. 125, 3071–3079. Liu, P., Chen, C., Kerr, B.J., Weber, T.E., Johnston, L.J., Shurson, G.C., 2014a. Influence of thermally-oxidized vegetable oils and animal fats on energy and nutrient digestibility in young pigs. J. Anim. Sci. 92. Liu, P., Chen, C., Kerr, B.J., Weber, T.E., Johnston, L.J., Shurson, G.C., 2014b. Influence of thermally oxidized vegetable oils and animal fats on growth performance, liver gene expression, and liver and serum cholesterol and triglycerides in young pigs. J. Anim. Sci. 92, 2960–2970. Liu, P., Kerr, B.J., Chen, C., Weber, T.E., Johnston, L.J., Shurson, G.C., 2014c. Methods to create thermally oxidized lipids and comparison of analytical procedures to characterize peroxidation. J. Anim. Sci. 92, 2950–2959. Liu, P., 2012. Biological assessment and methods to evaluate lipid peroxidation when feeding thermally-oxidized lipids to young pigs. In: PhD Diss. University of Minnesota, St. Paul. Lykkesfeldt, J., Svendsen, O., 2007. Oxidants and antioxidants in disease: oxidative stress in farm animals. Vet. J. 173, 502–511. McGill, J., McGill, E., Kamyab, A., Firman, J., 2011a. Effect of high peroxide value fats on performance of broilers in a normal immune state. Int. J. Poult. Sci. 10, 241–246. McGill, J., McGill, E., Kamyab, A., Firman, J., Ruiz-Feria, C., Larrison, E., Davis, M., Farnell, M., Carey, J., Grimes, J., 2011b. Effect of high peroxide value fats on performance of broilers in an immune challenged state. Int. J. Poult. Sci. 10, 665–669. Moreira, I., Mahan, D., 2002. Effect of dietary levels of vitamin E (all-rac-tocopheryl acetate) with or without added fat on weanling pig performance and tissue alpha-tocopherol concentration. J. Anim. Sci. 80, 663–669. National Forage Testing Association (NFTA), 1993. Forage analysis procedures, section C. http://foragetesting.org/lab procedure/sectionC/ (accessed 22.03.16.). NRC, 2012. Nutrient Requirements of Swine. Natl. Acad. Press, Washington, D. C. Pallarés, F.J., Yaeger, M.J., Janke, B.H., Fernandez, G., Halbur, P.G., 2002. Vitamin E and selenium concentrations in livers of pigs diagnosed with Mulberry Heart Disease. J. Vet. Diagn. Invest. 14, 412–414. Pegg, R.B., 2001. Spectrophotometric measurement of secondary lipid oxidation products, unit D2.4. Alternate protocol 2. In: Wrolstad, R.E. (Ed.), Current Protocols in Food Analytical Chemistry. John Wiley & Sons, Inc., Hoboken, NJ. Reeds, P.J., Fjeld, C.R., Jahoor, F., 1994. Do the differences between the amino acid compositions of acute-phase and muscle proteins have a bearing on nitrogen loss in traumatic states? J. Nutr. 124, 906–910. Renewable Fuels Association (RFA), 2015. Weekly U.S. Fuel Ethanol/Livestock Feed Production. Washington, DC, RFA. Rice, D., Kennedy, S., 1989. Vitamin E, selenium, and polyunsaturated fatty acid concentrations and glutathione peroxidase activity in tissues from pigs with dietetic microangiopathy (Mulberry Heart Disease). Am. J. Vet. Res. 50, 2101–2104. Seppanen, C., Csallany, A.S., 2002. Formation of 4-hydroxynonenal, a toxic aldehyde, in soybean oil at frying temperature. J. Am. Oil Chem. Soc. 79, 1033–1038. Shahidi, F., Zhong, Y., 2005. Lipid oxidation: measurement methods. In: Shahidi, F. (Ed.), Bailey’s Industrial Oil and Fat Products. Wiley, Hoboken, NJ, pp. 357–385. Shen, Y., Voilqué, G., Kim, J., Odle, J., Kim, S., 2012. Effects of increasing tryptophan intake on growth and physiological changes in nursery pigs. J. Anim. Sci. 90, 2264–2275. Song, R., Shurson, G.C., 2013. Evaluation of lipid peroxidation level in corn dried distillers grains with solubles. J. Anim. Sci. 91, 4383–4388. Spiteller, P., Kern, W., Reiner, J., Spiteller, G., 2001. Aldehydic lipid peroxidation products derived from linoleic acid. Biochim. Biophys. Acta, Mol. Cell. Biol. Lipids 1531, 188–208.

A.R. Hanson et al. / Animal Feed Science and Technology 216 (2016) 251–261

261

Tavárez, M.A., Boler, D.D., Bess, K.N., Zhao, J., Yan, F., Dilger, A.C., McKeith, F.K., Killefer, J., 2011. Effect of antioxidant inclusion and oil quality on broiler performance meat quality, and lipid oxidation. Poult. Sci. 90, 922–930. Thurnham, D., Davies, J., Crump, B., Situnayake, R., Davis, M., 1986. The use of different lipids to express serum tocopherol: lipid ratios for the measurement of vitamin E status. Ann. Clin. Biochem.: Int. J. Biochem. Med. 23, 514–520. Traber, M.G., Jialal, I., 2000. Measurement of lipid-soluble vitamins-further adjustment needed? Lancet 355, 2013–2014. Ullrey, D.E., 1981. Vitamin E for swine. J. Anim. Sci. 53, 1039–1056. Upton, J., Edens, F., Ferket, P., 2009. The effects of dietary oxidized fat and selenium source on performance glutathione peroxidase, and glutathione reductase activity in broiler chickens. J. Appl. Poult. Res. 18, 193–202. Varady, J., Gessner, D.K., Most, E., Eder, K., Ringseis, R., 2012. Dietary moderately oxidized oil activates the Nrf2 signaling pathway in the liver of pigs. Lipids Health Dis. 11, 1–9. Wahlen, R., Evans, L., Turner, J., Hearn, R., 2005. The use of collision/reaction cell ICP-MS for the determination of elements in blood and serum samples. Spectroscopy, 84–89. Wang, L., Yao, D., Chen, C., 2012. Effects of consuming oxidized vegetable oils on amino acid metabolism. FASEB J. 26 (637), 633. Wiseman, J., 2003. Utilisation of fats and oils and prediction of their energy-yielding value for non-ruminants. In: Arkansas Nutrition Conference September 9–11, 2003, Fayetteville, AR, pp. 1–17. Wu, G., 2009. Amino acids: metabolism, functions, and nutrition. Amino Acids 37, 1–17. Yu, B.P., 1994. Cellular defenses against damage from reactive oxygen species. Physiol. Rev. 74, 139. Yuan, S., Chen, D., Zhang, K., Yu, B., 2007. Effects of oxidative stress on growth performance, nutrient digestibilities and activities of antioxidative enzymes of weanling pigs. Asian-Australas. J. Anim. Sci. 20, 1600–1605.