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Title:Feeding peroxidized soybean oil to finishing pigs: Effects on performance, nutrient digestibility, carcass characteristics, and the shelf-life of loin chops and commercially manufactured bacon
Author(s):Overholt, Martin F.
Director of Research:Dilger, Anna C.
Doctoral Committee Chair(s):Dilger, Anna C.
Doctoral Committee Member(s):Boler, Dustin D.; Kerr, Brian J.; Dilger, Ryan N.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Oxidative stress
Pigs
Peroxidized oil
Pork
Shelf life,
Abstract:Fifty-six barrows (46.7 ± 5.1 kg initial BW) were randomly assigned to 1 of 4 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°Cfor 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. At 82 d pigs were slaughtered and hot carcass weight (HCW) and liver weights were recorded. Carcass characteristics and fresh loin quality were evaluated 1 d post-mortem. 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 were conducted on chops stored 0, 5, and 10 d, and thiobarbituric acid reactive substances (TBARS) were evaluated on chops stored 0 and 10 d. On d 83 carcasses were fabricated and bellies collected for recording of weight, dimensions, and flop distance. Belly adipose tissue cores were collected for analysis of iodine value (IV) by near-infrared spectroscopy (NIR-IV). Bacon was manufactured at a commercial processing facility and sliced bacon was subsequently transferred to food-service style packaging and subjected to 0, 30, 60, or 90 d storage at -20°C. Stored bacon was evaluated for thiobarbituric acid reactive substances (TBARS) and trained sensory evaluation of oxidized odor and flavor. Growth performance, nutrient digestibility, carcass traits, and bacon slicing yields were analyzed as a one-way ANOVA with the fixed effect of SO. Additionally, initial body weight was used as a covariate for analyses of growth performance and carcass traits. Shelf-life traits for both loin chops and sliced bacon were conducted as repeated measures in time using the mixed model approach, with fixed effects of SO and storage time. There were no differences observed in ADFI (P = 0.91), but ADG and GF were decreased in pigs fed 90°C SO diet (P ≤ 0.07) compared to pigs fed the other SO diets. Pigs fed the 90°C 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°C and 180°C had lower concentrations (P < 0.01) of plasma Trp compared to pigs fed the 22.5°C and 45°C SO treatments. Pigs fed 90°C SO had the greatest (P < 0.01) concentrations of F2-Isoprostane in plasma and urine TBARS compared to the other SO treatments. Carcasses of 90°C pigs weighed 6.0, 8.6, and 6.9 kg less than (P < 0.03) 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 180°C, and 180°C liver 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) BF depth, LMA, 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. There was no effect (P ≥ 0.30) of SO on belly weight, length, width, or thickness; but bellies of pigs fed 90°C SO had greater (P ≤ 0.04) flop distance (more firm) than all other SO treatments. Belly fat NIR-IV of pigs fed 90°C SO were 10.22 units less (P < 0.0001) than pigs fed 180°C SO, which were 2.99 and 3.29 units less than belly adipose tissue of pigs fed 22.5°C and 45°C SO, respectively. There was no effect of SO on brine uptake or cooking yield of commercially manufactured bacon. There was a trend (P = 0.09) for bacon manufactured from bellies of pigs fed 45°C and 90°C SO to have greater slicing yields than those from pigs fed 22.5°C and 180°C SO. There were no SO × storage time interactions (P ≥ 0.27) for any shelf life trait. There was no difference in TBARS, oxidized odor, or oxidized flavor among the four SO treatments, though all three shelf life metrics increased (P < 0.0001) with storage time. Overall, the change in FA composition and/or the presence of lipid peroxidation products in thermally peroxidized SO resulted in increased markers of oxidative stress and digestibility of GE and ether extract, resulting in drastically reduced growth performance and significantly lighter carcasses. Despite the negative effect on digestibility and growth, feeding thermally peroxidized SO had no effect on the shelf life of loin chops or bacon. In conclusion, pig producers should be weary of feeding thermally peroxidized fat sources, but packers and processors have little cause for concern when it comes to the stability and quality of their pork products.
Issue Date:2018-07-13
Type:Thesis
URI:http://hdl.handle.net/2142/101561
Rights Information:Copyright 2018 Martin Overholt
Date Available in IDEALS:2018-09-27
Date Deposited:2018-08


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