effect of distillers dried grains with solubles and...

M. Gaines, B. F. Wolter, S. N. Carr and F. K. McKeithC. M. Leick, C. L. Puls, M. Ellis, J. Killefer, T. R. Carr, S. M. Scramlin, M. B. England, A.

and shelf-life of fresh pork and baconEffect of distillers dried grains with solubles and ractopamine (Paylean) on quality

doi: 10.2527/jas.2009-2472 originally published online April 20, 20102010, 88:2751-2766.J ANIM SCI

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ABSTRACT: Pigs (n = 240) were allotted in a 5 × 2 factorial arrangement with 5 levels of distillers dried grains with solubles (DDGS): 0, 15, 30, 45, and 60%, and 2 ractopamine (RAC) levels: 0 and 5 mg/kg. Four pigs per pen (2 barrows, 2 gilts) closest to pen mean BW were used for meat quality evaluation. Loins (n = 119) were evaluated for objective color; moisture and fat; subjective color, marbling, and firmness; and drip loss. Bellies (n = 119) were evaluated for weight, length, width, thickness, objective fat color, and firm-ness. Cured bellies were evaluated for pump yield, cook loss, and sliced bacon cook loss. Loin thiobarbituric acid reactive substances (TBARS) were evaluated on enhanced (salt and phosphate) boneless chops held in modified atmosphere (80% O2/20% CO2) packages for 0, 7, 14, and 21 d. Bacon TBARS were evaluated on sliced bacon held in vacuum packages for 0, 28, 56, and 84 d. Fat samples were collected from each jowl and belly and evaluated for fatty acid profile and io-dine value (IV). Increasing DDGS decreased subjective marbling (P = 0.0134) and firmness (P = 0.0235), and increased drip loss (P = 0.0046). Distillers dried grains with solubles did not affect loin pH, subjective or objec-tive color, percent moisture, or percent fat (P > 0.05). The RAC decreased subjective color (P = 0.0239), marbling (P = 0.0445), and a* (P = 0.0355). Increas-

ing DDGS decreased belly weight (P = 0.0155), length (P = 0.0008), thickness (P = 0.0019), and firmness (P = 0.0054); decreased belly fat L* (P = 0.0818); and increased belly cook loss (P = 0.0890). Ractopamine did not affect any belly measurements, and there were no DDGS × RAC interactions (P > 0.05). Distillers dried grains with solubles did not affect loin TBARS at 0, 7, or 14 d. At 21 d, loin TBARS from 30, 45, and 60% DDGS groups were increased compared with 0 and 15% groups (P < 0.05). Ractopamine did not affect (P > 0.05) loin TBARS, and there were no (P > 0.05) DDGS × RAC interactions. Distillers dried grains with solubles and RAC did not affect bacon TBARS (P > 0.05). Increasing DDGS increased belly (P = 0.0207) and jowl (P < 0.0001) IV, and decreased MUFA:PUFA in belly (P < 0.0001) and jowl (P < 0.0001) fat. Ra-tio of SFA:unsaturated fatty acids decreased in jowl (P = 0.0002) and belly fat (P = 0.2815). Ractopamine did not affect fatty acid profiles or IV, and there were no DDGS × RAC interactions (P > 0.05). Results in-dicate that increased DDGS have minimal effects on loin quality, but decrease belly quality, bacon process-ing characteristics, and fat stability. Ractopamine does not negatively affect these characteristics and does not interact with DDGS.

Key words: belly quality, distillers dried grains with solubles, fatty acid, pig, shelf life

©2010 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2010. 88:2751–2766 doi:10.2527/jas.2009-2472

INTRODUCTION

With increased ethanol production, the use of dis-tillers dried grains with solubles (DDGS) has been

heavily investigated in recent years. Most researchers recommend less than 30% DDGS in grower-finisher pig diets to avoid decreased feed efficiency and soft belly fat (Wahlstrom et al., 1970; Weigel et al., 1997; Whitney et al., 2006; Widmer et al., 2008). Very limited informa-tion is available concerning use of DDGS over 30% in grower-finisher diets. Also, there is limited information regarding shelf-life and processing characteristics of pork from pigs fed increased DDGS. Previous research indicated that fatty acid profiles of pork reflect fatty acid profiles in diets of pigs (Averette Gatlin et al.,

Effect of distillers dried grains with solubles and ractopamine (Paylean) on quality and shelf-life of fresh pork and bacon

C. M. Leick,*1 C. L. Puls,* M. Ellis,* J. Killefer,*2 T. R. Carr,* S. M. Scramlin,* M. B. England,† A. M. Gaines,‡ B. F. Wolter,§ S. N. Carr,§ and F. K. McKeith*

*Department of Animal Sciences, University of Illinois, Urbana 61801; †Cargill Meat Solutions, Wichita, KS 67219; ‡The Maschhoffs, LLC, Carlyle, IL 62231; and §Elanco Animal Health,

a Division of Eli Lilly and Company, Greenfield, IN 46140

1 Present address: Department of Food Science, Nutrition, and Health Promotion, Mississippi State University, Mississippi State 39762.

2 Corresponding author: [email protected] September 10, 2009.Accepted March 26, 2010.

2751



2002); thus, it is also necessary to investigate fatty acid characteristics of pork from pigs fed increased DDGS.

Ractopamine hydrochloride (RAC; Paylean, Elanco Animal Health, Greenfield, IN) is a β-adrenergic ago-nist that increases lean deposition, decreases fat, and improves performance and feed efficiency (Apple et al., 2007b). Ractopamine has been shown to improve lean to fat ratios in the loin, ham, and shoulder, without negatively affecting loin quality or belly characteristics (Carr et al., 2005a,b; Rincker et al., 2005).

Previous researchers have not evaluated RAC in conjunction with DDGS. The potential for RAC to in-crease carcass lean and shift fatty acid profile could exacerbate the negative effects of DDGS on pork belly quality and processing characteristics. With a need to incorporate alternative feedstuffs into pig diets while maintaining increased production levels and meat qual-ity, the objectives of this research were to evaluate ef-fects of 5 levels of dietary DDGS (0, 15, 30, 45, and 60%) and 2 levels of RAC (0 and 5 mg/kg) on pork loin and belly quality, processing characteristics, shelf-life, and fatty acid profile and to examine interactions of DDGS and RAC.

MATERIALS AND METHODS

The protocol for this study was approved by the Uni-versity of Illinois Institutional Animal Care and Use Committee before the start of the study.

Animals, Treatments, and Sample Collection

Pigs (n = 240) were arranged in a randomized com-plete block design with a 5 × 2 factorial arrangement of treatments, consisting of 3 blocks, 5 levels of dietary DDGS inclusion: 0, 15, 30, 45, and 60%, and 2 levels of RAC inclusion: 0 and 5 mg/kg (Table 1). At about 40 kg BW, pigs were weighed individually and formed into outcome groups of 10 pigs of the same sex and BW. Animals were randomly allotted from within outcome group to form a block of 10 mixed-sex pens with 8 pigs per pen (4 barrows and 4 gilts). Pens within block were randomly allotted to 1 of the 5 DDGS inclusion levels to result in 2 pens per inclusion level per block. At wk 10 of the DDGS feeding period, the 2 pens within repli-cate and DDGS inclusion level were randomly allotted to 1 of the 2 RAC levels. Ractopamine was included in the diet for the final 4 wk of the 14-wk feeding period. There were 2 slaughter dates, with pigs in blocks 1 and 2 (160 pigs) killed on the first slaughter day and block 3 (80 pigs) killed 2 wk later on the second slaughter day. Four pigs (2 barrows, 2 gilts) per pen with final BW closest to the pen sex mean were selected for meat qual-ity evaluation. Pigs were transported to a commercial packing plant the night before slaughter and allowed to rest overnight. Pigs were humanely slaughtered accord-ing to standard commercial practices. At approximately 45 min postmortem, Fat-O-Meater (SFK Technology, Cedar Rapids, IA) sequence was recorded. After a 90-

min blast chill, carcasses from pigs designated for meat quality evaluation were individually identified with ed-ible carcass ink.

At 24 h postmortem, a sample for fatty acid analysis was cut from the dorsal side of the jowl on the right side of each carcass, bagged, and boxed. Carcasses were fabricated on a commercial fabrication line. The bone-in belly and bone-in loin from the right side of each carcass were collected off the line and placed in combos. Jowl samples, bellies, and loins were transported to the University of Illinois Meat Science Laboratory and held at 2°C overnight. At 48 h postmortem, jowl samples were vacuum packaged and frozen at −20°C.

Loin Quality Measurements

At 48 h postmortem, each loin was cut between the 10th and 11th ribs. The posterior section was used for subjective and objective quality evaluation, and the an-terior section was boned out to be used for drip loss, proximate analysis, and thiobarbituric acid reactive substances (TBARS). Ultimate pH was determined at the cut surface of the LM using a MPI pH Me-ter (model C033, Meat Probes Inc.). After a 20-min bloom, subjective scores for color, firmness, and mar-bling were taken on the cut surface of the LM (NPPC, 1999). Objective color measurements (L*, a*, and b*) were obtained from the cut surface of the LM using a Minolta Chromometer (model CR-300, Minolta Cam-era Company, Tokyo, Japan) set at the D65 angle of reflection value.

A 1.0-cm chop was obtained from the LM immedi-ately anterior to the 10th rib, trimmed of external fat, weighed, suspended in a Whirl-pak bag (Nasco, Fort Atkinson, WI), and held in a 2°C cooler for 24 h. Each chop was reweighed and drip loss was calculated as a percentage of initial weight. A second chop (2.5 cm) was frozen (−20°C) for subsequent proximate analy-sis. The remaining boneless loin sections were used for TBARS analysis.

Proximate Analysis

Fat and water contents were determined on the LM chop using the procedures described by Novakofski et al. (1989). Each chop was trimmed of external fat and con-nective tissue and homogenized using a Cusinart Food Processor (model DLC 5-TX, Cuisinart, Stamford, CT). Duplicate 10-g samples of each homogenized chop were weighed, placed in aluminum pans, and covered with filter paper. Each sample was oven-dried (110°C for 48 h), weighed to determine water content, extracted us-ing repeated washes of a warm chloroform:methanol so-lution, and weighed to determine fat content.

Belly Measurements

Spareribs, teat line, and excess flank muscle from the ham end were removed from each belly. A sample for

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fatty acid analysis was removed from the dorsal edge of each belly on the anterior end immediately dorsal to the scribe line. Each skin-on belly was weighed, and objec-tive color (L*, a*, b*) was obtained from the exposed fat surface dorsal to the center of the scribe line using a Minolta Chromometer (model CR-300, Minolta Cam-era Company) set at the D65 angle of reflection value. Belly thickness was measured at 6 points on the skin-on belly; at points intersecting approximately 25, 50, and 75% of the length of the belly at approximately 33 and 67% of the width of the belly. Firmness was evaluated by draping the belly over a stationary stainless-steel rod with the lean side up, measuring the distance from skin surface to skin. Length was measured from cranial to caudal end of each belly, and width was measured from dorsal to ventral edge of each belly.

Each belly was skinned using an air skinner and pumped to about 110% of green weight with a standard cure solution (13.6% Melozyme, 5% seasonings, 3.7% phosphate blend, 0.55% sodium erythorbate) using a Wolf-tec N-50 injector (Wolf-tec Inc., Kingston, NY). Bellies were allowed to equilibrate at 2°C for about 70 h. After equilibration, each belly was weighed to deter-mine pumped weight, hung ham end down on a smoke-house rack, and cooked to an internal temperature of

52.2°C in an Alkar smokehouse (Lodi, WI). After cook-ing, bacon slabs were held in a 2°C cooler overnight.

Each bacon slab was weighed to determine cooked weight and cut at the approximate location of the 10th rib. Internal temperature of the bacon slabs before slic-ing was approximately 2.7°C. Starting at the cut sur-face on the anterior half, bacon was sliced using a Bi-zerba slicer (model A404FB, Bizerba Food Equipment, Balingen, Germany) set at 2.6-mm thickness. Stacks of 10 slices each were vacuum-packaged and stored at 2°C for subsequent evaluation. Bacon slabs were not pressed or tempered before slicing, and this, combined with the generally soft belly fat, made slicing and stack-ing extremely difficult during the first slicing day. Thus during the second slicing day, each bacon slab was cut at the approximate location of the 10th rib, then the anterior half of each slab was placed on a tray, held in a blast freezer (−20°C) for approximately 45 min until an internal temperature of −1°C was reached, and sliced.

Sliced Bacon Cook Loss

Vacuum packaged stacks of sliced bacon were stored at 2°C for 28 d, then frozen at −20°C. Samples were thawed at 2°C overnight before cook loss evaluation.

Table 1. Diet formulation for grow-finish period1

Item

DDGS inclusion amount, %

0 15 30 45 60

0 mg/kg of RAC2 diet Corn 66.95 57.73 50.34 38.99 27.64 Soybean meal 26.91 21.80 14.72 11.11 7.51 Vitamins3 0.02 0.02 0.02 0.02 0.02 DDGS — 15.00 30.00 45.00 60.00 Liquid lysine 0.17 0.30 0.51 0.57 0.64 Trace mineral3 0.08 0.08 0.08 0.08 0.08 Fat (yellow grease) 3.98 3.38 2.78 2.50 2.21 Mono-calcium phosphate 0.64 0.30 — — — Salt 0.40 0.40 0.40 0.40 0.40 Limestone 0.81 0.95 1.08 1.27 1.46 Copper sulfate 0.05 0.05 0.05 0.05 0.05 Threonine — — 0.03 0.01 —5 mg/kg of RAC diet Corn 66.92 57.71 50.34 38.99 27.64 Soybean meal 26.91 21.80 14.72 11.11 7.51 Vitamins3 0.02 0.02 0.02 0.02 0.02 RAC 0.03 0.03 0.03 0.03 0.03 DDGS — 15.00 30.00 45.00 60.00 Liquid lysine 0.17 0.30 0.51 0.57 0.64 Trace mineral3 0.08 0.08 0.08 0.08 0.08 Fat (yellow grease) 3.98 3.38 2.78 2.50 2.21 Mono-calcium phosphate 0.64 0.30 — — — Salt 0.40 0.40 0.40 0.40 0.40 Limestone 0.81 0.95 1.08 1.27 1.46 Copper sulfate 0.05 0.05 0.05 0.05 0.05 Threonine — — 0.03 0.01 —

1Values are expressed as a percentage as-fed basis. Distillers dried grains with solubles (DDGS) source: Big River Resources, Burlington, IA.

2RAC = ractopamine hydrochloride (Paylean, Elanco Animal Health, Greenfield, IN). 3Vitamin and trace mineral inclusion rates were a minimum of 2.5 and 1.4 times NRC requirements, respec-

tively.

Distillers dried grains with solubles and ractopamine 2753



Eight slices from each package were weighed, placed on a rack, and cooked in a South Bend Convection Oven (model V-15, South Bend, IN) at 200°C for 11 min. Immediately after removal from the oven, slices were blotted once with paper towels and reweighed to determine cook loss.

TBARS

Boneless, enhanced blade chops and sliced bacon were used for determination of TBARS. Boneless anterior loin sections containing the LM and a portion of the spinalis were pumped with a 10% salt and phosphate solution to approximately 110% of green weight (tar-geted 0.35% salt and 0.35% phosphate in final product) using a Wolf-tec N-50 injector (Wolf-tec Inc.), held at 2°C for about 1 h, and reweighed to determine pump yield. Four chops were cut from each section and ran-domly assigned to 1 of 4 storage durations: 0, 7, 14, or 21 d. Chops from pigs of the same sex and the same pen were packaged together (2 chops per package, 2 packages per pen) using a modified atmosphere pack-ager (Koch LLC, Kansas City, MO) with an 80%/20% mixture of oxygen and carbon dioxide. The 7-, 14-, and 21-d packages were stored in a retail display case un-der fluorescent lighting. Packages were stacked in the display case so that 21-d packages were on the bottom layer, 14-d packages were in the middle, and 7-d pack-ages were on top. The 0-d chops were used immediately for TBARS. Vacuum packaged bacon samples were as-signed to 1 of 4 storage durations: 0, 28, 56, or 84 d. The 28-, 56-, and 84-d samples were stored in boxes at 2°C and moved to a retail display case with fluorescent lighting for the last 14 d of storage. The 0-d bacon samples were stored at −20°C for 7 d before analysis.

Samples from the same pen and sex were pooled and homogenized for TBARS. Duplicate 5-g samples of tissue were blended for 30 s in a blender (Waring Products, Torrington, CT) with 1 mL of 0.2 mg/mL butylated hydroxytoluene and 45.5 mL of 10% trichlo-roacetic acid in 0.2 M phosphoric acid. The homoge-nate was filtered through Whatman No. 1 filter paper, and filtrate was collected in a flask. Two 5-mL aliquots of filtrate were collected from each flask and placed in glass test tubes; 5 mL of 0.02 M thiobarbituric acid (TBA) was added to 1 tube, and 5 mL of deionized wa-ter was added to the other tube to be used as a blank. For every 10 TBARS samples, 1 additional sample was run as a spiked sample, so percent recovery could be determined for the assay. For the spiked samples, du-plicate 5-g tissue samples were homogenized with 1 mL of 0.2 mg/mL of butylated hydroxytoluene, 12 mL of 10 µM 1,1,3,3-tetramethoxypropane, and 32 mL of 10% trichloroacetic acid in 0.2 M phosphoric acid. Spiked samples were filtered, aliquotted, and TBA and water were added as described above. A standard curve [0, 1.25, 2.5, 5.0, and 7.5 mg of malondialdehyde (MDA)/mL] was set up using 25 µM 1,1,3,3-tetramethoxypro-

pane, 0.2 M TBA, and 10% trichloroacetic acid in 0.2 M phosphoric acid. All tubes were capped, inverted to mix, and stored in a dark cabinet at room temperature for about 18 h. Samples, blanks, and standards were read at 530 nm using a Beckman DU-640 Spectropho-tometer (Beckman Coulter Inc., Fullerton, CA). Excess homogenized tissue from each pooled meat sample was placed in a Whirl-Pak bag, frozen at −20°C, and later analyzed for moisture and fat content according to the procedures described previously. Fat content of each sample was used as a covariate when analyzing TBARS data.

Fatty Acid Profile

Belly fat samples and jowl fat samples were used for fatty acid analysis, with samples from pigs from the same pen being pooled and homogenized before extrac-tion. A 100-g sample was extracted by heating with a mixture of NaOH, methanol, and water; and cool-ing, then heating with a mixture of methanol and HCl. Samples were vortexed with a mixture of methyl tert-butyl ether and hexane mixture until clear; then, the aqueous layer was removed. Sodium hydroxide was add-ed to the organic layer and centrifuged at 850 × g for 10 min at 4°C. The organic layer was removed and dried under N2 gas, then redissolved in hexane. Fatty acids were determined using a gas chromatograph equipped with a flame ionization detector as described by Aver-ette Gatlin et al. (2002). Iodine values (IV) were cal-culated from the fatty acid profiles using the following equation: IV = 16:1 (0.95) + 18.1 (0.86) + 18.2 (1.732) + 18:3 (2.616) + 20:1 (0.785) + 22:1 (0.723) (AOCS, 1998). Fatty acids were calculated in grams per 100 g.

Statistical Analysis

Statistical analysis for loin and belly quality mea-surements and fatty acid profiles were conducted us-ing the MIXED procedure (SAS Inst. Inc., Cary, NC). The experimental unit was the pen of 4 animals (n = 30). The model included the fixed effects of DDGS and RAC, and the interaction between DDGS and RAC. Block and slaughter day were included as random ef-fects. Means and SE calculations were determined us-ing the least squares means statement, with the PDIFF option at a significance level of α = 0.05. Orthogonal polynomial contrast coefficients were used to determine linear, quadratic, and cubic effects of increasing DDGS level. There were no significant cubic effects of increas-ing DDGS; therefore, these P-values were not included in the tables. The CORR procedure of SAS was used to calculate Pearson correlation coefficients between jowl and belly fatty acid characteristics.

The TBARS were also analyzed using the MIXED procedure of SAS. The experimental unit was the pen of 4 animals (n = 30). The model included fixed ef-fects of DDGS, RAC, and days of storage, along with

Leick et al.2754



all interactions. Analysis was conducted via repeated measure by days of storage, and fat content was used as a covariate. Means and SE calculations were deter-mined using the least squares means statement, with the slice option to separate treatment means by sam-pling day at a significance level of α = 0.05. The slice statement showed that TBARS values were different on sampling d 21 (P < 0.05); therefore, orthogonal poly-nomial contrast coefficients were used to determine lin-ear, quadratic, and cubic effects of increasing DDGS on sampling d 21.

RESULTS AND DISCUSSION

Carcass Measurements

Population characteristics, including mean, maxi-mum, minimum, and SD for all carcass, loin, and belly measurements, are presented in Table 2. Final BW, HCW, and Fat-O-Meater measurement data are pre-sented in Table 3. Final BW decreased linearly (P = 0.0067) with increasing DDGS inclusion, such that final BW of pigs in the 0 and 15% DDGS treatments were greater than final BW of pigs in the 30, 45, and 60% DDGS treatments (P < 0.05). This may have been due

to a decrease in palatability of the greater DDGS di-ets, leading to decreased intake. Dressing percent (P = 0.0066) and HCW (P = 0.0015) also decreased linearly with increasing DDGS, similar to the results of Cook et al. (2005), Whitney et al. (2006), and Weimer et al. (2008). Widmer et al. (2008) reported that DDGS inclusion up to 20% did not affect HCW, which is simi-lar to the current study in which 0 and 15% DDGS had similar HCW. The data in the current study, along with that of previous researchers, suggest that DDGS inclusion levels up to 20% will not negatively affect pig BW and HCW. Ractopamine did not affect final BW (P = 0.3584), HCW (P = 0.2439), or dressing percent (P = 0.2764) and did not interact with DDGS to affect these measurements (P > 0.05). Other studies (Herr et al., 2001; Armstrong et al., 2004; Weber et al., 2006) reported improvements in these variables with RAC treatment.

Loin muscle depth (P = 0.2256), backfat depth (P = 0.7434), and calculated percent lean (P = 0.9638) were not affected by DDGS. Other researchers have reported a decrease in muscle depth (Whitney et al., 2006) but no change in backfat depth (Cook et al., 2005; Whitney et al., 2006; Widmer et al., 2008) with feeding DDGS. Ractopamine did not affect loin muscle

Table 2. Population characteristics

Item n1 Mean Minimum Maximum SD

Carcass measurement Final BW, kg 30 131.9 106.1 150.4 8.79 HCW, kg 30 98.9 78.5 114.3 7.62 Dressing percent 30 75.0 68.3 80.7 1.98 Loin depth, mm 30 57.1 35.0 70.0 6.17 Backfat depth, mm 30 17.9 10.0 38.0 4.81 Calculated percent lean 30 52.4 45.9 57.1 2.08Loin quality Color 30 2.8 2.0 4.0 0.48 Marbling 30 1.8 1.0 5.0 0.82 Firmness 30 2.7 1.0 4.0 0.75 LM L* 30 45.1 38.9 50.0 2.06 LM a* 30 6.4 3.9 9.4 1.22 LM b* 30 2.9 1.0 5.4 0.92 48 h pH 30 5.5 5.2 6.1 0.13 Drip loss, % 30 2.5 0.6 6.2 1.16 Moisture, % 30 74.6 71.9 76.2 0.82 Fat, % 30 2.0 1.0 4.2 0.63Belly quality Length, cm 30 62.7 55.4 71.4 3.14 Width, cm 30 33.4 25.9 38.1 2.15 Thickness, cm 30 3.3 2.0 4.9 0.56 Trimmed weight, kg 30 7.2 3.5 10.3 1.22 Flop distance, cm 30 8.6 0.5 22.1 4.00 Fat L* 30 71.7 65.4 75.3 2.10 Fat a* 30 5.2 2.0 9.3 1.47 Fat b* 30 6.8 3.8 9.8 1.26 Green (skinned) weight, kg 30 6.1 2.9 9.0 1.12 Pump uptake, % 30 7.9 3.4 12.3 2.46 Belly cook loss, % 30 9.5 5.9 14.7 1.74 Sliced bacon cook loss, % 30 64.2 50.5 77.7 4.67

1Thirty pens of pigs (2 barrows, 2 gilts per pen) fed in a 5 × 2 factorial arrangement with 5 dried distillers grains with solubles levels: 0, 15, 30, 45, and 60%, and 2 ractopamine hydrochloride (Paylean, Elanco Animal Health, Greenfield, IN) levels: 0 and 5 mg/kg.




depth (P = 0.0820), backfat depth (P = 0.3939), or cal-culated percent lean (P = 0.1657). This is in contrast to previous researchers (Uttaro et al., 1993; Herr et al., 2001), who reported that loin muscle depth increased with RAC treatment, but in agreement with other re-searchers (Stites et al., 1991; Armstrong et al., 2004; Weber et al., 2006), who have also reported no change in backfat depth due to RAC treatment. There were no interactions between DDGS and RAC to affect backfat and loin muscle depth or calculated percent lean (P > 0.05). Even though there were no significant interac-tions, previous research would suggest that loin muscle depth would decrease with dietary DDGS inclusion and increase with RAC inclusion. Thus, it may be possible that the combination of DDGS and RAC diminished the potential effects of the individual treatments on loin depth in the current study.

Loin Subjective Color, Marbling, and Firmness

The DDGS and RAC had minimal effects on subjec-tive quality measurements (Table 4). Dietary DDGS did not affect subjective color (P = 0.1099), similar to previous studies (Whitney et al., 2006; Weimer et al., 2008; Widmer et al., 2008), but led to a linear decrease in subjective marbling score (P = 0.0032). This is in contrast to the results of previous researchers (Whitney et al., 2006; Weimer et al., 2008; Widmer et al., 2008), who reported no change in marbling score with dietary DDGS inclusion. The current study evaluated DDGS at much greater inclusion levels, which may have driven the linear effect because marbling scores for the 45 and 60% DDGS treatments were less than those of the 0, 15, and 30% DDGS treatments. Because palatability of increased DDGS diets may be an issue and there was an overall decreased final BW and HCW for pigs in the greater DDGS inclusion levels, these results were not unexpected.

Other studies (Stites et al., 1991; Armstrong et al., 2004; Carr et al., 2005a) reported no difference in sub-jective color due to RAC. There was a decrease in mar-bling score (P = 0.0445) with the inclusion of RAC in the diet, but such a change was not reported by previous researchers (Stites et al., 1991; Carr et al., 2005a). Subjective firmness was affected by DDGS in-clusion level (P = 0.0235), such that loins from the 30% DDGS treatment were less firm than loins from all other treatments, unlike Whitney et al. (2006), who reported no change in firmness with dietary DDGS in-clusion. Ractopamine did not affect subjective firmness (P = 0.0916), similar to Rincker et al. (2005).

Loin Objective Color

Objective color values are presented in Table 4. The amount of DDGS did not affect loin L* (P = 0.2273), a* (P = 0.2220), or b* (P = 0.7920) values. Other studies (Whitney et al., 2006; Widmer et al., 2008) also

found no change in L* value with dietary DDGS inclu-sion levels up to 30%, so the results of the current study were not unexpected. Ractopamine did not affect or b* values (P = 0.1717); however, loins from pigs fed 5 mg/kg of RAC had greater L* values (P = 0.0498) and decreased a* values (P = 0.0355) than loins from 0 mg/kg RAC pigs, indicating a slightly lighter and less red color with the inclusion of RAC in the diet. There are conflicting results in the literature concerning the effect of RAC on objective color. Dunshea et al. (1993) found that RAC did not affect L*, a*, or b*. Conversely, other researchers reported that RAC led to a decrease in a* and b* values (Uttaro et al., 1993; Carr et al., 2005a,b). Color is a major visual cue for consumers in selecting fresh pork. Consumers have conveyed discrimination against pork that is perceived as too light, but have expressed an increased likelihood to purchase pork that exhibits a brighter pink color (Brewer and McKeith, 1999). The current study showed that the overall effects of DDGS and RAC on subjective and objective color were minimal, suggesting that the addition of RAC to pig diets containing DDGS has little to no effect on loin color.

Loin pH and Drip Loss

Dietary DDGS level did not affect (P = 0.0858) 48 h pH (Table 4). Other studies have reported differ-ent results regarding the impact of DDGS on ultimate pH. Widmer et al. (2008) found a trend for increased pH with increasing DDGS inclusion levels up to 20%, whereas Whitney et al. (2006) and Weimer et al. (2008) found no differences in pH with DDGS inclusion levels up to 30%. Ractopamine treatment did not affect loin pH (P > 0.10), similar to Dunshea et al. (1993) and Carr et al. (2005b), and did not interact with DDGS inclusion level.

Increasing DDGS led to a linear increase in drip loss (P = 0.0011). Whereas DDGS did not significantly af-fect pH, there was a trend for a decrease in 48 h pH with increasing DDGS level, which may have led to the changes in drip loss. As muscle pH approaches its iso-electric point around pH 5.0 to 5.1, water-holding ca-pacity is decreased (Price and Schweigert, 1987), which leads to increased water loss. Whitney et al. (2006) and Widmer et al. (2008) found that decreased dietary DDGS inclusion (up to 30%) did not affect drip loss. These studies reported no change or a trend toward increasing pH with increasing DDGS inclusion level, which supports the possibility that a pH change influ-enced the increased drip loss with increased DDGS in the current study. Furthermore, in the current study, drip loss was not different between the 0 and 15% DDGS treatments (P > 0.10), but drip loss was increased for the 30, 45, and 60% treatments, suggesting that greater DDGS may have driven the linear effect of DDGS on drip loss. Ractopamine did not affect (P = 0.1435) drip loss, similar to Uttaro et al. (1993), and did not inter-act with DDGS (P = 0.6075) to affect drip loss.

Leick et al.2756



Tab

le 3

. E

ffec

ts o

f di

still

ers

drie

d gr

ains

with

solu

bles

(D

DG

S) a

nd r

acto

pam

ine

hydr

ochl

orid

e (R

AC

) on

fin

al B

W a

nd c

arca

ss m

easu

rem

ents

1

Item

DD

GS

RA

CD

DG

S ×

RA

C

P-v

alue

0%15

%30

%45

%60

%SE

MP

-val

ueLin

ear

Qua

drat

ic0

mg/

kg5

mg/

kgSE

MP

-val

ue

Fin

al B

W, kg

135.

1b13

5.0b

129.

6a12

9.7a

129.

8a1.

980.

0397

0.00

670.

3528

13

1.1

132.

51.

500.

3584

0.

8303

HC

W, kg

102.

5c10

1.2bc

97.8

ab96

.9a

96.0

a1.

820.

0223

0.00

150.

5255

98

.199

.71.

430.

2439

0.

5578

Dre

ssin

g pe

rcen

t75

.8b

74.9

ab75

.4b

74.7

ab74

.0a

0.42

0.04

100.

0066

0.57

48

74.8

75.2

0.29

0.27

64

0.23

26Loi

n de

pth,

2 m

m59

.158

.655

.756

.355

.81.

330.

2256

0.04

380.

4724

56

.058

.20.

840.

0820

0.

3349

Bac

kfat

,2 m

m18

.219

.217

.817

.817

.51.

130.

7434

0.37

860.

7458

18

.517

.70.

870.

3939

0.

5085

Lea

n,2 %

52.6

52.2

52.3

52.4

52.5

0.43

0.96

380.

9242

0.52

54

52.1

52.7

0.29

0.16

57

0.88

22a–

c Mea

ns in

the

sam

e ro

w w

ith

differ

ent

supe

rscr

ipts

are

diff

eren

t (P

< 0

.05)

.1 T

hirt

y pe

ns o

f pi

gs (

2 ba

rrow

s, 2

gilt

s pe

r pe

n) f

ed in

a 5

× 2

fac

tori

al a

rran

gem

ent

of t

reat

men

ts w

ith

5 D

DG

S le

vels

: 0,

15,

30,

45,

and

60%

, an

d 2

RA

C (

Pay

lean

, E

lanc

o A

nim

al H

ealth,

G

reen

field

, IN

) le

vels

: 0

and

5 m

g/kg

.2 L

oin

mus

cle

dept

h an

d ba

ckfa

t de

pth

wer

e m

easu

red

and

perc

ent

lean

was

cal

cula

ted

usin

g a

Fat-

O-M

eate

r (S

FK

Tec

hnol

ogy,

Ced

ar R

apid

s, I

A)

on-lin

e in

a c

omm

erci

al p

acki

ng p

lant

.

Tab

le 4

. E

ffec

t of

dis

tille

rs d

ried

gra

ins

with

solu

bles

(D

DG

S) a

nd r

acto

pam

ine

hydr

ochl

orid

e (R

AC

) on

LM

qua

lity

char

acte

rist

ics1

Item

DD

GS

RA

CD

DG

S ×

RA

C

P-v

alue

0%15

%30

%45

%60

%SE

MP

-val

ueLin

ear

Qua

drat

ic0

mg/

kg5

mg/

kgSE

MP

-val

ue

Col

or2

2.9

3.0

2.8

2.6

2.8

0.10

0.10

990.

0471

0.61

31

2.9b

2.7a

0.07

0.02

93

0.50

79M

arbl

ing2

2.0bc

2.1c

2.0bc

1.5ab

1.7ab

0.13

0.01

340.

0032

0.81

71

2.0b

1.7a

0.08

0.04

45

0.05

92Fir

mne

ss2

2.8b

2.8b

2.3a

2.8b

2.8b

0.13

0.02

350.

4984

0.00

35

2.6

2.8

0.10

0.09

16

0.23

3148

h p

H5.

55.

65.

55.

55.

50.

070.

0858

0.05

430.

6483

5.

55.

50.

070.

6483

0.

3941

Min

olta

L*

44.6

44.9

45.5

45.2

45.4

0.32

0.22

730.

0564

0.30

63

44.8

a45

.4b

0.22

0.04

98

0.04

71M

inol

ta a

*6.

46.

96.

56.

26.

20.

220.

2220

0.15

290.

2493

6.

7b6.

2a0.

140.

0355

0.

9938

Min

olta

b*

2.8

3.0

2.8

2.8

2.9

0.21

0.79

200.

9363

0.75

61

3.0

2.8

0.17

0.17

17

0.25

09D

rip

loss

, %

1.8a

2.2ab

2.8c

2.9c

2.7bc

0.21

0.00

460.

0011

0.03

23

2.3

2.6

0.14

0.14

35

0.60

75M

oist

ure,

%74

.574

.774

.774

.574

.70.

150.

7577

0.55

840.

8732

74

.774

.60.

100.

6939

0.

7067

F at, %

2.0

2.2

1.9

1.9

2.1

0.10

0.25

950.

6906

0.32

20

2.0

2.0

0.06

0.67

74

0.04

18P

ump

upta

k e,3

%11

.111

.411

.712

.411

.60.

510.

5174

0.24

340.

4080

11

.811

.50.

330.

4561

0.

8120

a–c M

eans

in

the

sam

e ro

w w

ith

differ

ent

supe

rscr

ipts

are

diff

eren

t (P

< 0

.05)

.1 T

hirt

y pe

ns o

f pi

gs (

2 ba

rrow

s, 2

gilt

s pe

r pe

n) f

ed i

n a

5 ×

2 f

acto

rial

arr

ange

men

t of

tre

atm

ents

with

5 D

DG

S le

vels

: 0,

15,

30,

45,

and

60%

and

2 R

AC

(Pay

lean

, E

lanc

o A

nim

al H

ealth,

G

reen

field

, IN

) le

vels

: 0

and

5 m

g/kg

.2 S

cale

s: c

olor

, 1

= e

xtre

mel

y pa

le t

o 6

= e

xtre

mel

y da

rk; m

arbl

ing,

1 =

1%

to

10 =

10%

int

ram

uscu

lar

fat; fir

mne

ss, 1

= e

xtre

mel

y so

ft t

o 5

= e

xtre

mel

y fir

m (

NP

PC

, 19

99).

3 Bon

eles

s an

teri

or loi

n se

ctio

ns inj

ecte

d w

ith

a sa

lt a

nd p

hosp

hate

sol

utio

n.




Loin Proximate Analysis

There was an interaction between DDGS and RAC (P = 0.0418) on LM percent fat, such that within the 0 mg/kg RAC pigs, those fed 15% DDGS had a greater percent fat than all other DDGS inclusion levels, and within the 5 mg/kg RAC pigs, those fed 60% DDGS had a greater percent fat (P < 0.05) than all other DDGS inclusion levels. It is unclear why this interaction oc-curred; however, the magnitude of change in percent fat among all DDGS × RAC treatment combinations was less than 0.5%. As a main effect, DDGS did not affect LM percent moisture (P = 0.7577) or percent fat (P = 0.2595). As a main effect, RAC treatment also did not affect percent moisture (P = 0.6939) or percent fat (P = 0.6774); there was no interaction between DDGS and RAC to affect percent moisture (P = 0.7067). Previous research has also found no difference in percent mois-ture and percent fat due to RAC inclusion up to 10 mg/kg (Carr et al., 2005a,b).

Overall, increasing DDGS inclusion up to 60% had only minimal negative effects on subjective marbling, ultimate pH, and drip loss, indicating that even in-creased dietary DDGS inclusion in pig diets can pro-duce acceptable quality pork loins. Moreover, the current study demonstrated that there were no inter-actions between DDGS and RAC. This indicates that RAC may be incorporated into pig diets that include DDGS to obtain growth and efficiency benefits of RAC without negatively affecting loin quality.

Belly Measurements

Belly characteristics as affected by DDGS and RAC are presented in Table 5. In the current study, dietary DDGS inclusion levels greater than 15% negatively affected belly weight, linear measurements, and qual-ity. Increasing DDGS inclusion led to linear decreases in belly length (P < 0.0001), average thickness (P = 0.0002), trimmed weight (P = 0.0013), and firmness (P = 0.0005). There was also a trend (P = 0.0618) for a linear decrease in belly width with increasing levels of DDGS. It is generally reported that increased DDGS inclusion level will have a negative effect on pork bel-ly characteristics. Whitney et al. (2006) found linear decreases in belly thickness and firmness scores, and Weimer et al. (2008) reported decreased firmness scores with increased DDGS levels up to 30%. Widmer et al. (2008) also found a linear decrease in firmness score, but no change in thickness with increasing DDGS lev-els up to 20%, and Xu et al. (2008) reported that belly firmness was reduced in pigs fed 30% DDGS compared with 0% DDGS. In the current study, average belly thickness was less in the 30, 45, and 60% DDGS treat-ments compared with the 0 and 15% treatments, which were not different from each other. This, along with the results of previous studies, suggests that up to 20% DDGS in pig diets will not affect belly thickness. It ap-pears that even small inclusion (15% DDGS, in the cur-

rent study) of DDGS have a negative influence on belly firmness, with exacerbated results from DDGS inclu-sion levels greater than 15%. Interestingly, length, aver-age thickness, trimmed weight, and firmness were not different among the 30, 45, and 60% DDGS treatments. Although there was a marked difference between the less DDGS (0 and 15%) and the greater DDGS (30, 45, and 60%) levels, inclusion levels greater than 30% did not continue to have a deleterious effect on belly qual-ity. Thus, increasing dietary DDGS from 15 to 30% in the current study appeared to be the separation point for belly quality characteristics.

Ractopamine did not affect length (P = 0.0621), width (P = 0.6857), average thickness (P = 0.5014), trimmed weight (P = 0.4706), or firmness (P = 0.2750). Previous research has also reported no impact of RAC on belly length, width, thickness, and trimmed weight (Stites et al., 1991), as well as no impact on firmness (Carr et al., 2005a). In the current study, there was concern that the potential for RAC to increase linoleic acid content would combine with the unsaturated fatty acids in DDGS to have an additive negative effect on belly quality. However, RAC did not negatively influ-ence belly quality and did not interact with DDGS to affect any belly measurements or quality variables (P > 0.10). Similarly, Apple et al. (2007a) reported that RAC did not interact with fat source (soybean oil and beef tallow) to affect belly thickness or firmness.

Belly Fat Objective Color

The L* values were not affected by dietary DDGS level (P = 0.0818); however, it is interesting that belly fat from the 60% DDGS treatment was more than 1.3 L* units less than all other DDGS treatments (Table 5), indicating a darker fat color from this group. Di-etary DDGS did not affect belly fat a* (P = 0.7500) or b* (P = 0.9996) values. Widmer et al. (2008) reported a trend for decreasing L* value with increasing DDGS levels up to 20%, with no change in a* due to DDGS. A change in L* would not be unexpected because the increased unsaturation of fatty acids due to dietary DDGS would likely lead to a darker fat color; it is inter-esting that b* (yellowness) values did not change, how-ever, because fat sources with a greater proportion of unsaturated fatty acids are often commonly described as yellow. Ractapamine did not affect L* (P = 0.6968), a* (P = 0.8359), or b* (P = 0.6958) values measured on belly fat and did not interact with DDGS to af-fect objective color measurements (P > 0.05). Previous studies (Carr et al., 2005b; Apple et al., 2007a) also reported no change in objective fat color due to RAC or interactions between RAC and fat source.

Belly Processing Characteristics

Percent pump uptake was not affected by DDGS (P = 0.2941). Brewer et al. (1995) reported that thicker bellies retained more cure after equilibrium; thus, it

Leick et al.2758



Tab

le 5

. E

ffec

t of

dis

tille

rs d

ried

gra

ins

with

solu

bles

(D

DG

S) a

nd r

acto

pam

ine

hydr

ochl

orid

e (R

AC

) on

bel

ly q

ualit

y ch

arac

teri

stic

s1

Item

DD

GS

RA

CD

DG

S ×

RA

C

P-v

alue

0%15

%30

%45

%60

%SE

MP

-val

ueLin

ear

Qua

drat

ic0

mg/

kg5

mg/

kgSE

MP

-val

ue

Len

gth,

cm

65.5

c63

.9bc

62.6

ab62

.5a

61.5

a1.

050.

0008

<0.

0001

0.79

24

63.4

62.6

0.99

0.06

21

0.58

82W

idth

, cm

34.0

34.2

33.0

33.3

32.8

0.43

0.06

180.

0123

0.92

66

33.4

33.5

0.32

0.68

57

0.70

77A

vg. th

ickn

ess,

2 cm

3.6b

3.6b

3.1a

3.1a

3.0a

0.11

0.00

190.

0002

0.65

87

3.3

3.3

0.07

0.50

14

0.89

28T

rim

med

wei

ght, k

g7.

7b7.

7b7.

0a7.

0a6.

7a0.

250.

0155

0.00

130.

8316

7.

17.

30.

180.

4706

0.

6359

Flo

p di

stan

ce,3

cm11

.8b

9.5ab

7.3a

7.5a

6.8a

0.90

0.00

540.

0005

0.10

59

9.0

8.1

0.57

0.27

50

0.96

22Fa

t M

inol

ta L

*72

.272

.272

.071

.670

.30.

510.

0818

0.01

360.

1619

71

.871

.60.

320.

6968

0.

5023

F at

Min

olta

a*

5.5

5.3

5.5

5.1

5.0

0.37

0.75

000.

2582

0.73

19

5.2

5.3

0.30

0.83

59

0.20

38F a

t M

inol

ta b

*6.

86.

96.

86.

96.

80.

330.

9996

0.92

560.

9097

6.

86.

90.

250.

6958

0.

1816

Skin

ned

wt, k

g6.

6b6.

6b5.

9a5.

9a5.

7a0.

230.

0143

0.00

110.

7714

6.

16.

20.

170.

5082

0.

5759

Per

cent

pum

p7.

47.

17.

37.

28.

11.

570.

2941

0.15

870.

1271

7.

67.

31.

550.

2801

0.

1528

Bel

ly c

o ok

loss

,4 %

9.0

9.0

10.1

9.4

9.9

0.36

0.08

900.

0402

0.45

23

9.3

9.7

0.26

0.20

72

0.60

44B

acon

coo

k lo

ss,5

%63

.663

.765

.265

.364

.31.

530.

5555

0.30

780.

3223

64

.664

.31.

360.

6594

0.

3193

a–c M

eans

in

the

sam

e ro

w w

ith

differ

ent

supe

rscr

ipts

are

diff

eren

t (P

< 0

.05)

.1 T

hirt

y pe

ns o

f pi

gs (

2 ba

rrow

s, 2

gilt

s pe

r pe

n) f

ed in

a 5

× 2

fac

tori

al a

rran

gem

ent

with

5 D

DG

S le

vels

: 0,

15,

30,

45,

and

60%

, an

d 2

RA

C (

Pay

lean

, E

lanc

o A

nim

al H

ealth,

Gre

enfie

ld, IN

) le

vels

: 0

and

5 m

g/kg

.2 T

hick

ness

mea

sure

d at

6 p

oint

s in

ters

ecting

25,

50,

and

75%

the

len

gth

of t

he b

elly

and

33

and

67%

the

wid

th o

f th

e be

lly.

3 Dis

tanc

e fr

om s

kin

to s

kin

whe

n be

lly w

as d

rape

d sk

in-s

ide

dow

n ov

er a

sta

inle

ss-s

teel

rod

.4 P

roce

ssin

g lo

ss d

urin

g co

okin

g of

bel

lies

in s

mok

ehou

se.

5 Coo

king

los

s of

slic

ed b

acon

coo

ked

in a

con

vect

ion

oven

.




was surprising in the current study that there were no differences in pump uptake as a result of the very clear differences in belly thickness. Interestingly, bellies from the 60% DDGS treatment, which had the least average thickness, actually had a greater numerical pump yield than the other treatments (Table 5). Ractopamine did not affect percent pump, similar to the results of Stites et al. (1991). This was not unexpected because there were no differences in belly thickness or weight due to RAC.

Increasing levels of DDGS did not affect (P = 0.0890) belly cook loss in the smokehouse. There were numeri-cal increases (about 1%; Table 5) in belly cook loss in the greater (30, 45, and 60%) DDGS treatments com-pared with the lesser ones, which is likely related to the decreased fatness in bellies from greater DDGS inclu-sion levels, as well as increased levels of unsaturated fats, which have a reduced melting point and would be lost during the smoking process. Brewer et al. (1995) reported that belly thickness was positively correlated with yield of cooked bellies, so similar results in the current study would not have been unexpected. The inclusion of RAC did not affect belly cook loss and did not interact with DDGS or sex (P > 0.10), similar to the results of Stites et al. (1991). This is also not unexpected because there were no differences in belly thickness due to RAC.

Sliced Bacon Cook Loss

The inclusion level of DDGS did not affect sliced ba-con cook loss (P = 0.5555), similar to the results of Widmer et al. (2008). Kemp et al. (1969) reported that quality and fatness did not affect the cooking yield of sliced bacon, though there was a numerical increase in cook loss due to increased fatness. Brewer et al. (1995) observed an increase in sliced bacon cook loss due to increased belly thickness, which corresponded to an increase in percent fat. Both of these previous stud-ies suggested that fat was the main component lost in cooking; thus, in the current study, decreased belly weight led to the expectation that greater DDGS inclu-sion would lead to a greater bacon cook loss. Racto-pamine did not affect sliced bacon cook loss and did not interact with DDGS (P = 0.6594) to affect sliced bacon cook loss; this was not unexpected because there were no differences in belly weights or processing char-acteristics due to RAC. Precooked bacon specifications require a cook loss of at least 60% to ensure complete cooking (USDA, Food Safety and Inspection Service, 2003). It is thus important to identify factors that may contribute to differences in cooking loss in sliced ba-con to achieve consistency and efficiency in the grow-ing precooked bacon market. Although there was more than a 27% spread in sliced bacon cook loss in the cur-rent study, neither DDGS nor RAC, nor an interaction between the 2 factors, contributed to this variation. More research in a commercial setting could identify other factors that may affect sliced bacon cook loss

from pigs fed increased DDGS. Likewise, quality and acceptability of cooked bacon slices were not evaluated in the current study and warrant further investigation.

Loin TBARS

Loin TBARS as affected by DDGS are depicted in Figure 1. Loin TBARS values were not different be-tween d 0 and 7, but were increased from d 7 (P < 0.10) to d 14 (P < 0.10) and from d 14 to 21 (P < 0.05). The inclusion level of DDGS did not affect TBARS on d 0, 7, or 14 (P > 0.10); however, on d 21, loin TBARS from 30, 45, and 60% DDGS levels were greater than loin TBARS from 0 and 15% DDGS levels (P = 0.0004). Further emphasizing these differences, on d 21, mean TBARS values for the 30, 45 and 60% DDGS treat-ments were at or above 0.5 mg of TBARS/kg of tissue, which has been reported as the threshold for detection of rancidity of fresh pork (Tarladgis et al., 1960; Dun-shea et al., 2005; Wood et al., 2008). There was a limited amount of intramuscular fat in the LM; however, there was considerable seam fat and additional intramuscular fat in the spinalis and other muscles associated with the boneless blade chop. Total fat percentage of the chops was approximately 10.5%, which leaves a considerable amount of fat available for oxidation. The primary rea-son for the increase in TBARS in the greater DDGS treatment levels is likely the greater percentage of un-saturated fatty acids that were incorporated into the tissues, along with the oxygen-rich environment that was provided by the modified-atmosphere packaging. Previous research (Zhang and Sundar, 2005) has shown that increasing oxygen content in modified-atmosphere packaging led to increased TBARS values. Results of the current study indicate that after 21 d of storage in modified atmosphere packages, boneless blade chops from pigs fed dietary DDGS levels greater than 30% may reach a level of oxidative rancidity that is detect-able and objectionable to consumers. Loin TBARS were not affected by RAC treatment (P = 0.4984), and there were no treatment interactions (P = 0.2415).

Bacon TBARS

Bacon TBARS as affected by DDGS are depicted in Figure 2. Bacon TBARS values were not affected by DDGS (P = 0.2079). Pooled bacon TBARS values were increased from d 0 to 28 (P < 0.05), but were not increased from d 28 to 56 or 84 (P > 0.10). Pooled ba-con TBARS means were all below 0.3 mg of TBARS/kg of tissue, indicating that none of the bacon had be-come oxidized to unacceptable levels. There are several possible reasons why bacon TBARS values did not in-crease with extended storage time up to 84 d. First, bacon was held in vacuum packages and exposed to light for only the last 14 d of storage, thereby limiting exposure to oxygen and light, 2 primary factors in fat oxidation (Price and Schweigert, 1987). Second, nitrite in bacon tends to delay the onset of oxidative rancid-

Leick et al.2760



ity. During the production of cured pigments, nitrites cause iron ions to be retained in the heme compounds, making them unavailable for use as a catalyst of lipid oxidation. Lastly, residual nitrite can react to cause a nitrosation of MDA, which prevents MDA from react-ing with TBA in a TBARS test and thus decreases TBARS values (Fernández et al., 1997).

Jowl Fatty Acid Samples

Jowl fatty acid profiles as affected by DDGS and RAC are presented in Table 6. Data are presented only for fatty acids which were affected by DDGS or RAC in either jowl or belly fat samples. With increasing DDGS, C16:0 (P < 0.0001), C18:0 (P < 0.0001), C18:1 trans (P = 0.0002), C18:1 cis (P < 0.0001), and C18:3 (n-6) were decreased linearly (P < 0.05) in jowl samples, and C18:2 cis (P = 0.0065) were increased linearly. There was also a trend (P = 0.0969) for a linear decrease in C16:1 with increasing DDGS. Benz et al. (2008) also re-ported an increase in C18:2 in jowl fat with increasing DDGS levels up to 30%. The RAC did not affect con-centrations of any fatty acid (P > 0.10) except C12:0, where concentrations of C12:0 in jowls from pigs fed 5 mg/kg of RAC were less than those without RAC (P = 0.0164); however, the concentrations of C12:0 were numerically low (less than 1 g/100 g).

In jowl samples, MUFA:PUFA was decreased linearly (P < 0.0001) with increasing DDGS (Table 6). This can be accounted for by decreases in C16:1, C18:1 trans, and C18:1 cis, along with an increase in C18:2 cis. Rac-topamine did not affect MUFA:PUFA in jowl samples

(P = 0.9570) and did not interact with DDGS (P = 0.9636). Ratio of SFA:UFA was decreased linearly with increasing levels of DDGS (P < 0.0001) in jowl samples, similar to Benz et al. (2008). In the current study, this was due to the decreases in C16:0 and C18:0, coupled with increases in C18:2 cis and C20:3. Ractopamine did not affect SFA:UFA (P = 0.5759), and there were no interactions between DDGS and RAC (P = 0.9465).

Iodine value for jowl samples increased linearly with increasing levels of DDGS (P < 0.0001), similar to the findings of Benz et al. (2008). Because IV was calcu-lated from fatty acid concentrations, increased IV can be accounted for in part by increased C18:2 content, reflecting the increase in PUFA with increasing dietary DDGS. Ractopamine did not affect IV of jowl samples (P = 0.6262), and there were no interactions between DDGS and RAC (P = 0.8766).

Belly Fatty Acid Samples

Belly fatty acid profiles as affected by DDGS and RAC are presented in Table 7. With increasing DDGS, C18:1 cis was decreased linearly (P < 0.0001) and C18:2 cis was increased linearly (P < 0.0001) in belly samples, which is indicative of a shift from oleic to li-noleic acid due to increased unsaturation of dietary fat that has been reported in the literature. Benz et al. (2008) and Xu et al. (2008) also reported increases in C18:2 with increasing DDGS levels up to 30%. Racto-pamine did not affect concentrations of fatty acids in belly samples (P > 0.10), except C20:4, where concen-trations of C20:4 in bellies from pigs fed 5 mg/kg RAC

Figure 1. Effect of distillers dried grains with solubles (DDGS) on thiobarbituric acid reactive substances (TBARS) of boneless, enhanced blade chops. Evaluated on 30 pens of pigs (2 barrows, 2 gilts per pen) fed in a 5 × 2 factorial arrangement with 5 DDGS levels: 0, 15, 30, 45, and 60%, and 2 ractopamine hydrochloride (RAC; Paylean, Elanco Animal Health, Greenfield, IN) levels: 0 and 5 mg/kg. Boneless blade chops were enhanced with salt and phosphate solution and stored in modified atmosphere packaging (80% O2/20% CO2). Color version available in the online PDF.




were less than 0 mg/kg RAC (P = 0.0470). This is similar the results of Weber et al. (2006); however, the concentrations of C20:4 were numerically small (less than 1 g/100 g) in the current study and in the work of Weber et al. (2006). Other researchers (Xi et al., 2005; Apple et al., 2007a) also reported minimal changes in belly fatty acid profile due to RAC.

In belly samples, MUFA:PUFA was decreased lin-early (P < 0.001) with increasing (Table 7). The RAC did not affect MUFA:PUFA in belly samples (P = 0.9505), and there were no DDGS × RAC interactions (P = 0.7011). Xi et al. (2005) reported a decrease in MUFA:PUFA due to RAC; however, this was at greater RAC inclusion levels (9 mg/kg). Unlike in jowl samples, SFA:UFA was not affected by DDGS in belly samples (P > 0.10). Also, RAC did not affect SFA:UFA (P = 0.2391), and there were no interactions between DDGS and RAC (P = 0.8722).

The IV for belly fat samples increased linearly with increasing DDGS (P = 0.0020), similar to the findings of Whitney et al. (2006), Benz et al. (2008), and Xu et al. (2008), but in contrast to the findings of Widmer et al. (2008), who reported no change in IV with DDGS inclusion levels up to 20%. Again, in the current study, changes in IV may be due in part to increased C18:2. Ractopamine did not affect IV of belly samples (P = 0.2973), and did not interact with DDGS (P = 0.8611). This is in agreement with previous research (Carr et al., 2005b; Xi et al., 2005; Weber et al., 2006).

Mean IV for all treatments (including 0% DDGS) in the current study were increased (Tables 6 and 7) in jowl and belly samples compared with the IV threshold of 70 that is often used in industry to characterize soft

fat. This was likely due to the fact that yellow grease, rather than choice white grease, was used as a supple-mental fat source in all diets (Table 1). Also, mean IV for belly fat samples was greater than that of jowl fat samples. This is the opposite of what was expected and what has been shown in previous studies (Benz et al., 2008).

Correlations Between Jowl and Belly Fatty Acid Characteristics

Correlations between jowl and belly fat samples are presented in Table 8. Pearson correlation coefficients between jowl and belly samples were calculated for IV, MUFA content, PUFA content, MUFA:PUFA, and SFA:UFA. Changes in fatty acid profile of the belly are of great interest to the meat industry; however, obtain-ing belly fat samples for analysis is difficult and results in a devaluation of the carcass. Jowl samples are easier to access on the carcass and could be collected at line speeds. Thus, it is important to understand the correla-tion between jowl and belly fatty acid profiles to deter-mine whether jowl samples will accurately reflect the fatty acid characteristics of the belly. There were sig-nificant correlations between jowl and belly samples for IV, MUFA content, PUFA content, and MUFA:PUFA (P < 0.05). There was no significant correlation be-tween jowl and belly samples for SFA:UFA. The results of the current study suggest that fatty acid profiles of jowl samples are correlated to those of belly samples; thus, sampling jowl fat may be useful in a commer-cial setting for evaluating fat quality when a belly fat sample is not accessible.

Figure 2. Effect of distillers dried grains with solubles (DDGS) on thiobarbituric acid reactive substances (TBARS) of bacon. Evaluated on 30 pens of pigs (2 barrows, 2 gilts per pen) fed in a 5 × 2 factorial arrangement of treatments with 5 DDGS levels: 0, 15, 30, 45, and 60%, and 2 ractopamine hydrochloride (RAC; Paylean, Elanco Animal Health, Greenfield, IN) levels: 0 and 5 mg/kg. Stacks of sliced bacon were stored in vacuum packages. Color version available in the online PDF.

Leick et al.2762



Tab

le 6

. E

ffec

t of

dis

tille

rs d

ried

gra

ins

with

solu

bles

(D

DG

S) a

nd r

acto

pam

ine

hydr

ochl

orid

e (R

AC

) on

jow

l fa

tty

acid

cha

ract

eris

tics

1,2

Item

DD

GS

RA

C

DD

GS

×

RA

C

P-v

alue

0%15

%30

%45

%60

%SE

MP

-val

ueLin

ear

Qua

drat

ic0

mg/

kg5

mg/

kgSE

MP

-val

ue

C12

:00.

20.

10.

20.

20.

20.

010.

4914

0.32

530.

9328

0.

2b0.

1a0.

120.

0164

0.

4066

C16

:020

.7c

19.8

b18

.8ab

18.3

a17

.6a

0.48

0.00

20<

0.00

010.

6418

19

.218

.90.

300.

4703

0.

9368

C16

:12.

702.

482.

292.

232.

060.

160.

0969

0.00

780.

6970

2.

42.

30.

100.

3907

0.

4422

C18

:06.

6c6.

1bc5.

4ab4.

9a4.

7a0.

310.

0019

<0.

0001

0.55

73

5.4

5.7

0.20

0.38

87

0.15

35C

18:1

tra

ns0.

6b0.

6b0.

4a0.

4a0.

4a0.

060.

0010

0.00

020.

0609

0.

50.

50.

060.

3490

0.

0667

C18

:1 c

is38

.4c

36.5

b34

.6ab

33.5

a32

.6a

0.86

0.00

01<

0.00

010.

2879

34

.935

.40.

660.

4952

0.

8451

C18

:2 t

rans

0.6

0.3

0.1

0.1

0.2

0.15

0.15

950.

0470

0.11

44

0.3

0.2

0.09

0.79

84

0.52

40C

18:2

cis

22.1

a26

.7b

30.5

c32

.6c

34.9

d1.

15<

0.00

01<

0.00

010.

1759

29

.229

.50.

730.

8188

0.

8762

C18

:3n-

30.

4b0.

2a0.

1a0.

2a0.

2a0.

060.

0235

0.00

650.

0487

0.

20.

20.

040.

5740

0.

9847

C18

:3n-

60.

40.

40.

40.

40.

30.

060.

5109

0.17

610.

3193

0.

40.

40.

050.

5152

0.

5682

C20

:00.

10.

10.

10.

10.

10.

010.

4981

0.26

230.

7482

0.

10.

10.

010.

9143

0.

1565

C20

:11.

11.

41.

41.

41.

30.

090.

1537

0.27

220.

0414

1.

41.

30.

060.

3267

0.

1722

C20

:20.

60.

80.

90.

90.

90.

090.

1313

0.02

090.

2875

0.

80.

80.

060.

4831

0.

7128

C20

:40.

30.

30.

30.

40.

30.

060.

4644

0.71

790.

3426

0.

30.

30.

060.

6487

0.

2850

IV3

78.4

a83

.7b

87.6

bc90

.4cd

93.4

d1.

35<

0.00

01<

0.00

010.

2672

86

.487

.00.

850.

6262

0.

8766

Tot

al M

UFA

42.8

c40

.9bc

38.6

ab37

.4a

36.3

a0.

840.

0002

<0.

0001

0.35

54

39.1

39.3

0.55

0.71

48

0.91

50Tot

al P

UFA

24.5

a28

.9b

32.5

c34

.7cd

37.0

d1.

13<

0.00

01<

0.00

010.

2151

31

.531

.60.

720.

8905

0.

8789

MU

FA:P

UFA

1.8c

1.4b

1.2ab

1.1a

1.0a

0.08

<0.

0001

<0.

0001

0.08

39

1.3

1.3

0.05

0.95

70

0.96

36SF

A:U

FA4

0.44

d0.

41cd

0.38

bc0.

36ab

0.34

a0.

010.

0002

<0.

0001

0.48

37

0.39

0.38

0.01

0.57

59

0.94

65a–

d Mea

ns in

the

sam

e ro

w w

ith

differ

ent

supe

rscr

ipts

are

diff

eren

t (P

< 0

.05)

.1 T

hirt

y pe

ns o

f pi

gs (

2 ba

rrow

s, 2

gilt

s pe

r pe

n) f

ed in

a 5

× 2

fac

tori

al a

rran

gem

ent

of t

reat

men

ts w

ith

5 D

DG

S le

vels

: 0,

15,

30,

45,

and

60%

, an

d 2

RA

C (

Pay

lean

, E

lanc

o A

nim

al H

ealth,

G

reen

field

, IN

) le

vels

: 0

and

5 m

g/kg

.2 F

atty

aci

ds e

xpre

ssed

in

g/10

0 g.

3 Cal

cula

ted

usin

g th

e eq

uation

: io

dine

val

ue (

IV)

= 1

6:1

(0.9

5) +

18.

1 (0

.86)

+ 1

8.2

(1.7

32)

+ 1

8:3

(2.6

16)

+ 2

0:1

(0.7

85)

+ 2

2:1

(0.7

23);

AO

CS,

199

8.4 U

FA =

uns

atur

ated

fat

ty a

cid.




Tab

le 7

. E

ffec

t of

dis

tille

rs d

ried

gra

ins

with

solu

bles

(D

DG

S) a

nd r

acto

pam

ine

hydr

ochl

orid

e (R

AC

) on

bel

ly fat

ty a

cid

char

acte

rist

ics1,

2

Item

DD

GS

RA

C

DD

GS

×

RA

C

P-v

alue

0%15

%30

%45

%60

%SE

MP

-val

ueLin

ear

Qua

drat

ic0

mg/

kg5

mg/

kgSE

MP

-val

ue

C12

:00.

20.

10.

10.

20.

10.

050.

2648

0.42

500.

7342

0.

10.

10.

00.

6589

0.

4842

C16

:12.

32.

11.

71.

71.

80.

230.

2613

0.07

410.

1939

1.

91.

90.

10.

7021

0.

5475

C18

:07.

15.

37.

05.

05.

10.

790.

1826

0.10

320.

9667

6.

35.

50.

50.

2362

0.

9220

C18

:1 t

rans

0.6

0.4

0.3

0.4

0.3

0.17

0.24

920.

0874

0.32

00

0.5

0.3

0.1

0.20

94

0.73

00C

18:1

cis

38.4

b37

.7b

33.2

a32

.5a

32.5

a1.

060.

0003

<0.

0001

0.16

22

34.4

35.3

0.8

0.26

81

0.68

96C

18:2

tra

ns0.

10.

60.

40.

30.

20.

190.

4009

0.71

430.

1300

0.

30.

30.

10.

7259

0.

7485

C18

:2 c

is25

.1a

29.5

ab31

.9b

36.7

c36

.4c

1.61

0.00

01<

0.00

010.

2328

31

.332

.61.

10.

3520

0.

7182

C18

:3n-

30.

20.

30.

10.

10.

10.

060.

3133

0.16

040.

5170

0.

20.

10.

00.

9353

0.

4620

C18

:3n-

60.

50.

30.

40.

40.

40.

060.

0895

0.21

960.

2448

0.

40.

30.

00.

1186

0.

5450

C20

:00.

10.

10.

00.

10.

10.

030.

1565

0.14

380.

1996

0.

10.

10.

00.

1698

0.

8684

C20

:11.

41.

11.

41.

51.

30.

140.

3355

0.70

920.

9633

1.

31.

20.

10.

5949

0.

0133

C20

:20.

90.

90.

80.

70.

90.

200.

9629

0.89

020.

5248

0.

71.

00.

10.

1492

0.

7040

C20

:40.

20.

20.

30.

20.

30.

050.

4791

0.34

560.

3284

0.

3b0.

2a0.

00.

0470

0.

7852

C16

:018

.016

.518

.815

.816

.71.

780.

6221

0.50

080.

9337

18

.016

.41.

30.

2540

0.

7443

IV3

82.4

a89

.2ab

88.9

ab96

.7b

95.6

b3.

460.

0207

0.00

200.

5000

89

.192

.02.

60.

2973

0.

8611

Tot

al M

UFA

46.6

b41

.1b

36.5

a36

.0a

35.8

a1.

080.

0004

<0.

0001

0.10

66

38.0

38.8

0.7

0.38

34

0.47

84Tot

al P

UFA

27.2

a31

.8ab

34.1

b38

.6c

38.5

c1.

770.

0004

<0.

0001

0.24

17

33.4

34.7

1.2

0.37

42

0.77

07M

UFA

:PU

FA1.

6c1.

3b1.

1a0.

9a0.

9a0.

07<

0.00

01<

0.00

010.

0220

1.

21.

20.

10.

9505

0.

7011

SFA

:UFA

40.

400.

340.

390.

310.

320.

040.

2815

0.09

440.

9903

0.

370.

330.

030.

2391

0.

8722

a–c M

eans

in

the

sam

e ro

w w

ith

differ

ent

supe

rscr

ipts

are

diff

eren

t (P

< 0

.05)

.1 T

hirt

y pe

ns o

f pi

gs (

2 ba

rrow

s, 2

gilt

s pe

r pe

n) f

ed in

a 5

× 2

fac

tori

al a

rran

gem

ent

of t

reat

men

ts w

ith

5 D

DG

S le

vels

: 0,

15,

30,

45,

and

60%

, an

d 2

RA

C (

Pay

lean

, E

lanc

o A

nim

al H

ealth,

G

reen

field

, IN

) le

vels

: 0

and

5 m

g/kg

.2 F

atty

aci

ds e

xpre

ssed

in

g/10

0 g.

3 Cal

cula

ted

usin

g th

e eq

uation

: io

dine

val

ue (

IV)

= 1

6:1

(0.9

5) +

18.

1 (0

.86)

+ 1

8.2

(1.7

32)

+ 1

8:3

(2.6

16)

+ 2

0:1

(0.7

85)

+ 2

2:1

(0.7

23);

AO

CS,

199

8.4 U

FA =

uns

atur

ated

fat

ty a

cid.

Leick et al.2764



The results of the current study showed that increas-ing dietary DDGS inclusion level led to decreases in final BW, HCW, and dressing percent. Furthermore, the effects of RAC on carcass composition were not as apparent in the current study as in previous research. Loin quality was not substantially affected by DDGS or RAC, which suggests that even high levels of DDGS can produce acceptable quality pork loins. However, stor-age duration and conditions need to be further inves-tigated because oxidative rancidity of chops from pigs fed 30% or more DDGS was approaching unacceptable levels after 21 d of storage in a high-oxygen environ-ment. Increasing dietary DDGS above 15% decreased belly quality, which would lead to difficulty in process-ing and slicing bacon, but the effects of DDGS were not exacerbated by RAC inclusion. Also, shelf-life of bacon was not affected by DDGS, likely due to the process-ing and packaging conditions, but future research could investigate other storage conditions that might increase oxidation in sliced bacon. Additional research could be conducted to investigate processing techniques and in-gredients that may alleviate the problems associated with soft belly fat. The current study suggests that 15% DDGS in grower-finisher pig diets will produce accept-able quality pork with minimal effect on shelf-life or belly quality. Furthermore, RAC may be incorporated into pig diets containing DDGS without negatively af-fecting loin or belly quality.

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Table 8. Pearson correlation coefficients between jowl and belly fatty acid characteristics1

Variable r P-value

IV2 0.394 0.0313Total MUFA3 0.766 <0.0001Total PUFA3 0.592 0.0006MUFA:PUFA3 0.698 <0.0001SFA:UFA3,4 0.163 0.3898

1Evaluated on 30 pens of pigs (2 barrows, 2 gilts per pen) fed in a 5 × 2 factorial arrangement of treatments with 5 distillers dried grains with solubles levels: 0, 15, 30, 45, and 60%, and 2 ractopamine hydrochloride (Paylean, Elanco Animal Health, Greenfield, IN) levels: 0 and 5 mg/kg.

2Calculated using the equation: iodine value (IV) = 16:1 (0.95) + 18.1 (0.86) + 18.2 (1.732) + 18:3 (2.616) + 20:1 (0.785) + 22:1 (0.723); AOCS, 1998.

3Fatty acids expressed in g/100 g.4UFA = unsaturated fatty acid.




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