Alternating dietary fat sources for growing-ﬁ nishing pigs ...pdfs.semanticscholar.org/9c7f/93574b4cc771644b5ff0d4cfc90ce9a… · 3Corresponding author: [email protected] Received

1509

Alternating dietary fat sources for growing-fi nishing pigs fed dried distillers grains with solubles: II. Fresh belly and bacon quality characteristics1

N. A. Browne,*2 J. K. Apple,*3 C. V. Maxwell,* J. W. Yancey,* T. M. Johnson,* D. L. Galloway,* and B. E. Bass*

*Department of Animal Science, University of Arkansas Division of Agriculture, Fayetteville 72701

ABSTRACT: Crossbred pigs (n = 216) were used to test the effects of phase-feeding beef tallow (BT) and yellow grease (YGr) on fresh belly and bacon quality characteristics of growing-fi nishing swine fed dried distillers grains with solubles (DDGS). Pigs were blocked by initial BW (26.0 ± 5.3 kg) before allotment to pens (6 pigs/pen), and pens (6 pens/block) were assigned randomly to 1 of 6 dietary treatments: 1) corn-soybean meal-based grower and fi nisher diets formulated with 4.7% YGr fed during all 5 feeding phases (YG15); 2) corn-soybean meal-based diets formulated with 5.0% BT fed during all 5 phases (BT15); 3) diets containing 5.0% BT fed during the fi rst 2 phases and diets with 4.7% YGr fed the last 3 phases (YG345); 4) diets formulated with 5.0% BT fed during fi rst 3 phases and diets contain-ing 4.7% YGr fed during the last 2 phases (YG45); 5) diets containing 4.7% YGr fed during the fi rst 3 phases and diets with 5.0% BT fed during the last 2 feeding phases (BT45); or 6) diets formulated with 4.7% YGr fed during the fi rst 2 phases and diets with 5.0% BT fed during the last 3 phases (BT345). All dietary treatments were formulated with 30% dried distillers grains with solubles (DDGS) during the fi rst 3 phases, 15% DDGS in the fourth phase, and

no DDGS during the last phase. Fresh belly quality data were collected on the left-side bellies, whereas bacon from the right-side bellies was prepared under commercial processing conditions. Additionally, USDA-certifi ed No. 1 slices were collected for cook-ing characteristics and sensory panel evaluations. Bellies from the YG15-fed pigs were softer (P ≤ 0.05) than bellies from BT15-fed pigs; however, instrumentally measured belly fi rmness was not (P ≥ 0.06) different among treatments. Concentrations of palmitic, stearic, and oleic acids, as well as all SFA and all MUFA, were greater (P < 0.01) in bellies from BT15- than YG15-fed pigs. In contrast, proportions of linoleic acid, all PUFA, and iodine value were greater (P < 0.01) in belly fat from YG15-fed pigs in comparison with BT15-fed pigs. Yield of com-mercially processed bacon (P ≥ 0.06), mechanical bacon tenderness (P ≥ 0.69), and bacon palatability attributes (P ≥ 0.55) were not affected by the dietary treatments. Thus, results of this study indicated that phase-feeding BT to pigs fed diets formulated with DDGS produced minor improvements in fresh belly fi rmness due to greater proportions of SFA but had no effect on yields of commercially processed bacon or bacon quality characteristics.

Key words: bacon, beef tallow, dried distillers grains with solubles, pork bellies, yellow grease

© 2013 American Society of Animal Science. All rights reserved. J. Anim. Sci. 2013.91:1509–1521 doi:10.2527/jas2012-5529

1The authors express their sincere appreciation to the Fats and Protein Research Foundation (Alexandria, VA) for fi nancial support of this project and Darling International Inc. (Irvi ng, TX) for donation of fat sources. In addition, the authors are grateful to C. Bradley, C. Hart, L. Hess, J. Wyatt, and L. McDonald (University of Arkansas) for care and well-being of pigs on the trial; R. Stackhouse and C. Fuller (University of Arkansas) for assistance with fresh belly data collection; A. Coffman and C. Moon (University of Arkansas) for assistance in laboratory analyses; D. Delozier (University of Arkansas) for her assistance with bacon sensory analysis; and D. Bonfy and the employees of Wright Brand Foods (Vernon, TX) for their assistance with bacon processing.

2Present address: Cargill Meat Solutions, Wichita, KS 672023Corresponding author: [email protected] June 4, 2012.Accepted December 12, 2012.

INTRODUCTION

Soft pork fat and soft bellies are the culprit of con-siderable economic losses associated with fabrication diffi culties, reduced product yields, unattractive pro-cessed products (especially bacon), reduced product shelf-life, and subsequent consumer discrimination of pork products (Averette Gatlin et al., 2002; Apple et al., 2009b). Even though pork fat has been shown to be inversely related to pork carcass leanness, the increased incidence of soft pork fat and pork bellies

Published December 2, 2014

Browne et al.1510

is the consequence of elevating the PUFA by feeding large quantities of dried distillers grains with solubles (DDGS), highly unsaturated greases and oils, or both to growing-fi nishing swine (Benz et al., 2010; Apple et al., 2011).

It has been suggested that the complete removal of polyunsaturated dietary fat sources from the late-fi nisher diet(s) would reverse the negative effects of these fat sources on pork fatty acid composition and fi rmness. However, results from Apple et al. (2009a) implied that the complete removal of a polyunsaturated fat source from the late-fi nishing diet(s) would have few benefi cial effects, whereas replacing the polyunsatu-rated fat source with a saturated fat source would have only minimal impacts on pork fat quality. Furthermore, replacement of DDGS with either beef tallow (BT) or choice white grease during the last 26 d before slaughter failed to reverse the effects of DDGS on pork quality (Stevens et al., 2009). Based on the fi ndings of Apple et al. (2009a,b,c), it was hypothesized that feeding a more saturated fat source during the growing phases would establish more saturated pork fat depots, so when large amounts of DDGS or polyunsaturated fat sources were fed in later dietary phases, the negative effects of elevat-ing dietary PUFA on belly fi rmness would be negligi-ble. Therefore, the objective of this experiment was to test the effects of phase-feeding BT and yellow grease (YGr) on belly and bacon quality characteristics and belly fatty acid composition.

MATERIALS AND METHODS

Pig husbandry and all experimental protocols were in accordance with standard operating procedures for swine experiments and approval (protocol 10041) issued by the University of Arkansas Interdepartmental Animal Care and Use Committee before initiating this study.

Animals and Diets

Crossbred pigs (n = 216) from the mating of GPK-35 females (Newsham Choice Genetics, Des Moines, IA) and line 380 sires (PIC North American, Hendersonville, TN) were blocked by BW (26.0 ± 5.3 kg) into 6 blocks of 36 pigs/block. Pigs within blocks were allotted ran-domly to mixed-gender pens (3 barrows and 3 gilts/pen), and pens (6 pens/block) were assigned randomly to 1 of 6 dietary treatments: corn-soybean meal-based grower and fi nisher diets formulated with 4.7% YGr (Darling International Inc., Irving, TX) fed during all 5 feeding phases (YG15); 2) corn-soybean meal-based grower and fi nisher diets formulated with 5.0% BT (Darling International Inc., Irving, TX) fed during all 5 feeding phases (BT15); 3) diets containing 5.0% BT fed during

the fi rst 2 feeding phases and diets containing 4.7% YGr fed during the last 3 phases (YG345); 4) diets formulated with 5.0% BT fed during the fi rst 3 phases and diets con-taining 4.7% YGr fed during the last 2 phases (YG45); 5) diets with 4.7% YGr fed during the fi rst 3 phases and diets with 5.0% BT fed during the last 2 phases (BT45); or 6) diets containing 4.7% YGr fed during the fi rst 2 feeding phases and diets with 5.0% BT fed during the last 3 phases (BT345). Pigs were fed a 5-phase diet, with phase 1 (grower-I), 2 (grower-II), 3 (fi nisher-I), 4 (fi nisher-II), and 5 (fi nisher-III) diets being fed for 19, 18, 19, 20, and 27 d, respectively. All dietary treat-ments were formulated to represent commercial inclu-sion levels of DDGS, with 30% DDGS during phases 1, 2, and 3; 15% DDGS during phase 4; and no DDGS during phase 5. Within each feeding phase, diets were isocaloric and isolysinic, and formulated to meet or ex-ceed NRC (1998) requirements for growing-fi nishing pigs (Table 1). Fatty acid composition of the 2 dietary fat sources and each diet, as well as details concerning pig housing, are reported in Browne et al. (2012).

Pig Slaughter and Carcass Data Collection. At the end of the 103-d feeding trial (average BW of 124.1 kg), all pigs were transported approximately 8 h (720 km) to a commercial pork packing plant (Cargill Meat Solutions, Beardstown, IL) and slaughtered according to humane, industry-accepted procedures after a 6-h lairage pe-riod. Before carcass fabrication, bellies from right and left sides of each carcass were individually identifi ed, and during fabrication, fresh pork bellies (IMPS #408) were captured, placed in combos, and transported under refrigeration to the University of Arkansas Red Meat Research Abattoir for quality data collection.

Belly Quality Data Collection

Upon arrival at the abattoir, the length, width, thickness (mean of cranial, caudal, dorsal, and ventral measurements), and temperature (belly fi rmness was measured on all bellies between 1.7 and 2.8°C) were measured on the left-side bellies. Subjective belly fi rm-ness was measured according to the bar-suspension (fl op) method of Theil-Cooper et al. (2001), where the distance between belly ends was measured when the length of the belly was suspended perpendicular (skin-side up and skin-side down) to a 1.9-cm-diameter bar. Belly fi rmness angle (the upper angle of the isosceles triangle formed by suspending the belly across the bar) was also calculated using the equation of Whitney et al. (2006): cos-1 ([{0.5 x L2}– D2]/{0.5 x L2}), where L is the belly length and D is the distance between belly ends when suspended perpendicular to the bar. Additionally, instrumental color (L*, a*, and b* values) of the belly fat was measured with a Hunter Miniscan XE (Hunter Associate Laboratories,

Phase-feeding fat on belly and bacon quality 1511

Reston, VA) using illuminant C and a 10° standard ob-server, as well as subjective Japanese fat color scores (The Japan Ham & Sausage Processors Cooperative Assoc., Shibuya-ku, Tokyo, Japan). A 3.8-cm-diameter strip from the anterior end of each belly was removed, vacuum-packaged, and stored at -20°C to be used to ob-jectively measure belly fi rmness. Then, approximately 250 g of subcutaneous (s.c.) fat from the area between the fi rst and second teats of each belly was removed and stored in Whirl-Pak bags (NASCO, Fort Atkinson, WI) at −20°C for fatty acid analysis.

Objective belly fi rmness was measured according to the Instron puncture test of Trusell et al. (2011). Briefl y, belly strips were thawed at 1°C for 48 h before each belly strip was separated into 4 equal-length portions. Temperature of each belly section was measured (belly puncture was measured on all sections between 1.7 and 2.8°C) before thickness of each section was measured with calipers to determine belly thickness. Subsequently, belly sections were placed skin-side down on a lower fl at plate, and were punctured to 65% of their specifi c thickness with an Instron testing machine (model 4466; Instron Corp., Canton, MA) equipped with a 10-cm-long, 1.3-cm-diameter, rounded-tip puncturing bar, a 50-kg load cell, and a crosshead speed of 100 mm/min.

Bacon Data Collection

Bellies from the right side of each carcass were transported under refrigeration to a commercial bacon processing plant (Wright Brand Foods, Vernon, TX), where each belly was identifi ed during curing and ther-mal processing. Weights were recorded at all stages of processing (before skinning, after brine injection, after smoking, and after slicing) and yields were calculated as a percentage of the green belly weight. Sliced bacon from each belly was captured, individually boxed, and transported under refrigeration back to the University of Arkansas Red Meat Research Abattoir for cook-ing characteristics and sensory panel evaluations of cooked bacon.

Upon arrival at the abattoir, sliced bacon from the center of each slab was identifi ed and subsequently vac-uum-packaged and stored at −20°C for cooking char-acteristics (n = 6 slices/belly) and sensory panel evalu-ations (n = 15 slices/belly). Bacon was thawed at 1°C for 24 h, removed from vacuum packaging, placed on paper plates, and L*, a*, and b* values of the bacon fat were determined from a mean of 3 random readings made with a Hunter Miniscan XE (Hunter Associate Laboratories, Reston, VA) using illuminant D65 and a 10° standard observer. Bacon was then weighed and cooked in a commercial oven (Zephaire E mod-el; Blodgett Oven Co., Burlington, VT) preheated to 204.4°C for 9 min. After removal from the oven, bacon was blotted dry with paper towels and weighed, and the difference between precooked and cooked weights was used to calculate cooking loss percentage. A 6.0-cm sec-tion of bacon was removed from the center of the slices, and each section was subsequently sheared once with a 10-blade, Allo-Kramer shear force device attached to an Instron Universal Testing Machine (model 446; Instron Corp., Canton, MA), with a 200-kg tension/compression load cell and a crosshead speed of 100 mm/min. Shear

Table 1. Composition (as-fed basis) of experimental diets

ItemFeeding phase1

Grower-I Grower-II Finisher-I Finisher-II Finisher-IIIIngredient, %

Corn 38.41 44.45 49.29 64.95 78.92Soybean meal 23.55 17.95 13.20 12.55 13.50DDGS 30.00 30.00 30.00 15.00 0.00Yellow grease2 4.68 4.68 4.68 4.68 4.68Beef tallow2 0.00 0.00 0.00 0.00 0.00Sand2 0.32 0.32 0.32 0.32 0.32Dicalcium phosphate

0.740 0.44 0.35 0.72 0.96

Limestone 1.200 1.100 1.133 0.885 0.695Salt 0.400 0.400 0.400 0.400 0.400L-lysine HCl 0.300 0.275 0.250 0.213 0.200L-threonine 0.017 0.009 0.000 0.013 0.053Vitamin premix3 0.150 0.150 0.150 0.100 0.100Mineral premix4 0.150 0.150 0.150 0.125 0.125Ethoxiquin 0.030 0.030 0.030 0.030 0.030Tylan-40 0.050 0.050 0.050 0.025 0.025

Calculated composition, %CP 22.56 20.37 18.49 15.51 13.19Total lysine 1.314 1.141 0.990 0.849 0.770SID lysine 1.120 0.960 0.821 0.723 0.685SID M+C5 0.658 0.607 0.562 0.483 0.419SID threonine 0.683 0.600 0.526 0.467 0.457SID tryptophan 0.198 0.169 0.143 0.127 0.119Total P 0.638 0.560 0.525 0.516 0.491Available P 0.360 0.300 0.280 0.260 0.220Total Ca 0.750 0.630 0.610 0.580 0.561ME, Mcal/kg 3.533 3.549 3.553 3.552 3.5501Grower-I, grower-II, fi nisher-I, fi nisher-II, and fi nisher-III diets were fed

pigs with BW of 26.5 to 42.7, 42.7 to 61.6, 61.6 to 81.1, 81.1 to 101.0, and 101.0 to 124.1 kg, respectively.

2Beef tallow (5%) replaced yellow grease (4.68%) and sand (0.32%) re-sulting in an isocaloric diet within each phase.

3Premix supplied 6614 IU of vitamin A, 827 IU of vitamin D3, 26 IU of vitamin E, 2.7 mg of vitamin K, 16.5 mg of pantothenic acid, 30 mg of niacin, 5 mg of ribofl avin, and 26 ìg of vitamin B12 per kilogram of premix (Nutra Blend Corp., Neosho, MO).

4Premix supplied 138 mg/kg of Fe from ferrous sulfate, 138 mg/kg of Zn from zinc sulfate, 33 mg/kg of Mn as manganous sulfate, 13.8 mg/kg of Cu from cop-per sulfate, 0.25 mg/kg of Se from sodium selenite, and 0.25 mg/kg of I from calcium iodate per kilogram of premix (Nutra Blend Corp.).

5Standard ileal digestible (SID) methionine and cysteine.

Browne et al.1512

force values of the cooked bacon were determined from a mean of 4 bacon sections.

Bacon Sensory Panel Evaluations

For each of the 18 sensory panel sessions, 12 slices of bacon from a pig from each dietary treatment were thawed for 48 h at 1°C in vacuum-packaged bags, placed randomly across cooking racks (9 slices/rack), and cooked in convection ovens preheated to 218.3°C for 17 min. Immediately after removal from the oven, bacon was blotted dry with paper towels and an ap-proximate 6.0-cm bacon section was removed from the center of each slice and served warm to each panelist in a random order. Panelists were trained according to guidelines outlined by Cross et al. (1978). Within each session, 8 to 12 trained panelists were provided unsalt-ed saltine crackers, distilled drinking water, and apple juice or apple slices to cleanse their palates between samples. Traits evaluated by the sensory panel included initial crispiness, bacon fl avor intensity, saltiness, sus-tained chewiness, oiliness, and off-fl avor intensity (1 = extremely crisp, bland, bland, crumbly, abundant, and abundant to 8 = extremely soft, intense, salty, chewy, none, and none).

Fatty Acid Analysis

Duplicate 5-g belly s.c. fat samples were weighed and placed in 30-mL beakers, and reweighed. Beakers were then placed into vacuumed fl asks attached to the mani-fold of a Labconco freeze-dryer (Model 4.5; Labconco Corp., Kansas City, MO) with a temperature setting of –50°C and a vacuum of less than 10 mm of Hg for 72 h. Then, duplicate 30-mg, freeze-dried belly fat samples were placed in tubes and subjected to direct transesterifi -cation by incubating in 2.0 mL of 0.2 M methanolic KOH at 50°C for 45 min, with vortex-mixing 2 to 3 times/min until tissues were dissolved (Murrieta et al., 2003). Tubes were allowed to cool to room temperature, and 1 mL of saturated NaCl and 2 mL of highly purifi ed hexane were added to each tube. Then, 1 mL of hexane containing 1 mg/mL of an internal standard (glyceryl tridecanoic acid [13:0]) was added to 16 × 125-mm screwcap tubes. Hexane was evaporated under a hood to concentrate the internal standard. Tubes were subsequently vortexed and centrifuged at 1100 × g and 22°C to separate phases. Fatty acid methyl esters (FAME) in the hexane layer (approximately 1 mL) were transferred to GLC vials that contained 1.0-mm bed of anhydrous sodium sulfate. Separation of FAME was achieved by GLC (Model 5890 Series II GC with automatic sample injector [HP-7673] with HP-3365software; Hewlett-Packard, Avondale, PA) equipped with a 100-m capillary column (0.25-mm in-

ternal diameter; Model SP2560 Fused Silica Capillary; Supelco Inc., Bellefonte, PA). Helium was the carrier gas (20 cc/sec) at a split ratio of 60:1. Oven tempera-ture was maintained at 150°C for 5 min, ramped at 4°C/min to 194°C for 15 min, and then ramped at 2.50°C/min to 235°C for 16.25 min, whereas injector and detec-tor temperatures were maintained at 250°C. Qualifi cation of peaks was accomplished using purifi ed standards ob-tained from Supelco (Bellefonte, PA; 37 component mix) and individual acids from Nu-Check Prep (Elysian, MN) and Martreya (Pleasant Gap, PA). C13 was the internal standard to quantify peak areas.

The total proportion of SFA was the sum of the weight percentages of capric (10:0), lauric (12:0), my-ristic (14:0), pentadecanoic (15:0), palmitic (16:0), mar-garic (17:0), stearic (18:0), and arachidic (20:0) acids, whereas the total proportion of all MUFA was calcu-lated by summing the weight percentages of myristo-leic (14:1), palmitelaidic (16:1t), palmitoleic (16:1c), 10-trans-heptadecenoic (17:1t), all 18-carbon fatty ac-ids with a single trans double bond (total 18:1t), oleic (18:1c9), vaccenic (18:1c11), and gadoleic (20:1c11) acids. Additionally, the total percentage of all PUFA in-cluded linoleic (18:2n-6), total CLA (including the iso-mers 18:2c9t11, 18:2c9c11, 18:2c10c12, and 18:2t9t11), γ-linolenic (18:3n-6), α-linolenic (18:3n-3), eicosadi-enoic (20:2), dihomo-γ-linolenic (20:3n-6), eicosatri-enoic (20:3n-3), arachidonic (20:4n-6), docosapentae-noic (22:5n-3), and docosahexaenoic (22:6n-3) acids. The PUFA:SFA was calculated by dividing the total proportion of PUFA by the total proportion of SFA, whereas the iodine value (IV) of each section was cal-culated according to the AOCS (1998) equation: (0.95 × [Σ16:1]) + (0.86 × [Σ18:1]) + (1.732 × [Σ18:2]) + (2.616 × [Σ18:3]) + (0.785 × [20:1]), where brackets indicate the weight percentage concentration.

Statistical Analyses

Data were analyzed as a randomized complete block design, with blocks based on initial BW and pen as the experimental unit. Analysis of variance was achieved using the mixed models procedure (SAS Inst. Inc., Cary, NC). The lone fi xed effect in all statistical models was the dietary treatment, whereas initial BW block was considered a random effect in models for fresh belly and bacon characteristics; however, in the ANOVA for the cooked bacon sensory data, panelist within session was also included in the model as a random effect. Least squares means were computed, and specifi c contrasts were included in all data analysis to specifi cally compare 1) YGr vs. BT diets (YG15 vs. BT15); 2) BT vs. YG in the last 3 feeding phases (BT345 vs. YG345); and 3) BT vs. YG in the last 2 feeding phases (BT45 vs. YG45).


To discern the effects of BT or YGr feeding dura-tion on fresh belly and bacon quality characteristics, the ANOVA was again generated with the mixed models procedure as previously described, with feeding du-rations for BT of 47 (BT45), 66 (BT345), and 103 d (BT15) or for YGr of 37 (YG45), 56 (YG345), and 103 d (YG15), as the lone fi xed effect in the model. Least squares means were generated within each fat source, and orthogonal contrasts were used to test the linear and quadratic effects of either BT or YGr feeding duration on fresh belly and bacon characteristics. Because the durations of BT or YGr feeding were not spaced evenly, PROC IML of SAS was used to generate the appropri-ate linear and quadratic contrast statements. In addition, slope analysis was performed using PROC GLM of SAS to detect differences in the rate of change between di-etary fat sources, and when a signifi cant (P ≤ 0.05) slope difference was noted, PROC REG of SAS was used to generate the slopes of the linear and quadratic polyno-mial equations.

RESULTS AND DISCUSSION

Belly CharacteristicsLength, width, and thickness of fresh bellies did not

(P ≥ 0.07) differ among the dietary treatments (Table 2). Even though duration of feeding BT did not (P ≥ 0.25) alter dimensional measurements of fresh bellies, belly length increased (quadratic, P = 0.02) as the duration of feeding YGr-formulated diets increased from 37 to 103 d (Table 3). More importantly, bellies from the YG15-fed pigs were softer (P ≤ 0.05) than bellies from the BT15-fed pigs, as indicated by greater belly fl op distances and fl op angles, regardless of how bellies were oriented to the bar (Table 2). Interestingly, belly fi rmness was not (P ≥ 0.44) affected by duration of dietary BT, but fl op distance and fl op angle decreased (linear, P < 0.01) with increasing days fed YGr when bellies were oriented to the bar skin-side down (Table 3). Yet, puncture values were similar (P ≥ 0.06) among the dietary treatments (Table 2), and the duration of feeding YGr- (P ≥ 0.08) or BT-formulated diets (P ≥ 0.21) did not affect fresh belly puncture values (Table 3).

Belly fi rmness score decreased linearly as DDGS were added to the diet (Widmer et al., 2008; Leick et al.,

Table 2. Effect of phase-feeding fats on fresh pork belly characteristics

ItemDietary treatments1

SEP-value2

YG15 YG345 YG45 BT45 BT345 BT15 A B CNo. of pens 6 6 6 6 6 6Width, cm 33.5 34.1 33.7 34.2 33.8 33.4 0.43 0.83 0.59 0.43Length, cm 66.7 66.8 68.6 67.6 68.3 67.6 0.56 0.25 0.07 0.22Thickness, cm 2.70 2.90 2.85 2.86 2.87 2.90 0.096 0.14 0.81 0.91Belly fl op, cm

Skin-side up 14.54 16.74 16.20 17.40 18.45 17.11 0.921 0.05 0.18 0.34Skin-side down 12.17 15.16 14.53 15.68 15.06 14.78 0.843 0.03 0.93 0.32

Belly angle, °3

Skin-side up 25.2 28.9 27.3 30.0 31.3 29.5 1.56 0.05 0.26 0.20Skin-side down 21.0 26.2 24.4 26.8 25.5 25.3 1.39 0.03 0.73 0.20Puncture force, kg 7.75 8.51 9.43 7.30 8.25 7.42 0.756 0.76 0.81 0.06

Fat colorLightness (L*)4 81.72 81.07 81.60 81.03 81.65 82.20 0.524 0.52 0.45 0.45Redness (a*)4 10.42 10.90 10.50 11.37 10.12 10.19 0.445 0.71 0.22 0.18Yellowness (b*)4 13.69 14.02 13.78 14.86 13.10 13.41 0.397 0.63 0.11 0.07Visual color score5 2.5 2.5 2.3 2.5 2.3 2.3 0.16 0.30 0.48 0.621YG15 = grower and fi nisher diets formulated with 4.7% yellow grease (YGr) fed during all 5 feeding phases; YG345 = diets formulated with 5.0% beef

tallow (BT) during the fi rst 2 feeding phases and 4.7% YGr fed during the last 3 phases; YG45 = diets formulated with 5.0% BT fed during the fi rst 3 phases and 4.7% YGr fed during the last 2 phases; BT45 = diets with 4.7% YGr fed during the fi rst 3 phases and 5.0% BT fed during the last 2 phases; BT345 = diets containing 4.7% YGr fed during the fi rst 2 feeding phases and 5.0% BT fed during the last 3 phases; and BT15 = diets formulated with 5.0% BT fed during all 5 feeding phases.

2 Probability values for the specifi c contrasts of: A = YG15 vs. BT15; B = BT vs. YGr in the last 3 feeding phases (YG345 vs. BT345); and C = BT vs. YGr in the last 2 feeding phases (YG45 vs. BT45).

3Calculated as cos-1{[(0.5 × L2) – D2]/(0.5 × L2)}, where L is the belly length and D is the distance between belly ends when suspended perpendicular to the bar (greater angle indicates a fi rmer belly; Whitney et al., 2006).

4L* = measures darkness to lightness (greater L* values indicate a lighter color); a* = measures redness (greater a* values indicate a redder color; and b* = measures yellowness (greater b* values indicate a more yellow color).

5Japanese fat color standards (1 = creamy white to 4 = pinkish white; The Japan Ham & Sausage Processors Cooperative Assoc., Shibuya-ku, Tokyo, Japan).

Browne et al.1514

2010; Xu et al., 2010a,b), and bellies from pigs that were fed 30% DDGS were softer than bellies from pigs fed 0 or 20% DDGS (Whitney et al., 2006). Also, as corn oil was increased in the diet from 0 to 4%, belly fi rm-ness decreased linearly as measured by the belly fl op test (Apple et al., 2011). Softer bellies were most likely a consequence of increased concentrations of dietary unsaturated fatty acids supplied by DDGS and added oils. On the other hand, belly bending was decreased by the addition of tallow to the diet (Jackson et al., 2009). However, subjective and objective belly fi rmness was not affected by formulating swine diets with either choice white grease (Weber et al., 2006) or poultry fat (Engel et al., 2001).

There was no (P ≥ 0.07) effect of phase-feeding BT or YGr on L*, a*, b*, and visual fat color values of belly fat (Table 2); however, belly fat yellowness (b*) values decreased (quadratic, P = 0.04) as the time fed BT increased from 47 to 103 d (Table 3). Even though Japanese fat color scores were not affected by the dura-tion of dietary BT (P ≥ 0.42) or YGr (P ≥ 0.37) inclusion (Table 3), quadratic slopes differed (P = 0.04) between dietary BT and YGr durations, implying that fat color scores decreased at a greater rate the longer YGr was consumed by growing-fi nishing pigs (Fig. 1).

In contrast, the color of belly fat from pigs fed BT was lighter (greater L* values) and redder (greater a* values) than belly fat from soybean oil-fed pigs (Apple et al., 2007). However, belly fat color was not affected

by including choice white grease, poultry fat (Engel et al., 2001), or increasing inclusion levels of DDGS (Xu et al., 2010b) in swine diets. Moreover, no differences in L*, a*, and b* values were observed in the LM (Whitney et al., 2006; Xu et al., 2010a,b), backfat, or belly fat (Xu et al., 2010a) of pigs fed up to 30% DDGS.

Table 3. Effect of feeding duration of beef tallow or yellow grease on fresh pork belly characteristics

ItemBeef tallow, d Yellow grease, d Slopes1

47 66 103 SE Lin2 Q2 37 56 103 SE Lin2 Q2 Lin2 Q2

Width, cm 34.2 33.8 33.4 0.47 0.25 0.85 34.1 33.7 33.5 0.38 0.31 0.62 0.65 0.63Length, cm 67.6 68.3 67.6 0.61 0.93 0.38 66.8 68.6 66.7 0.51 0.44 0.02 0.19 0.16Thickness, cm 2.86 2.87 2.90 0.111 0.79 0.98 2.90 2.85 2.70 0.080 0.09 0.99 0.21 0.21Belly fl op, cm

Skin-side up 17.40 18.45 17.11 0.953 0.70 0.36 16.74 16.20 14.54 0.889 0.10 0.94 0.68 0.73Skin-side down 15.68 15.06 14.78 0.847 0.46 0.75 15.16 14.53 12.17 0.840 0.02 0.83 0.37 0.43

Belly angle, °3

Skin-side up 30.01 31.35 29.47 1.581 0.70 0.45 28.95 27.30 25.24 1.540 0.12 0.77 0.59 0.52Skin-side down 26.82 25.51 25.33 1.367 0.44 0.60 26.16 24.39 21.05 1.405 0.02 0.87 0.28 0.32Puncture force, kg 7.35 8.30 7.42 0.728 0.88 0.21 8.53 9.47 7.75 0.749 0.08 0.59 0.91 0.99

Fat colorLightness (L*)4 81.03 81.65 82.20 0.617 0.17 0.75 81.11 81.60 81.72 0.399 0.36 0.55 0.72 0.66Redness (a*)5 11.37 10.12 10.19 0.505 0.18 0.21 10.89 10.50 10.42 0.374 0.46 0.60 0.90 0.98Yellowness (b*)4 14.86 13.10 13.41 0.422 0.07 0.04 14.00 13.78 13.69 0.371 0.59 0.78 0.17 0.22Visual color score5 2.5 2.3 2.3 0.18 0.42 0.73 2.5 2.3 2.5 0.14 0.84 0.37 0.02 0.041Probability values that slopes of linear and quadratic polynomial equations differ between fat sources.2Lin = linear and Q = quadratic.3Calculated as cos-1{[(0.5 × L2)– D2]/(0.5 × L2)}, where L is the belly length and D is the distance between belly ends when suspended perpendicular to the

bar (greater angle indicates a fi rmer belly; Whitney et al., 2006).4L* = measures darkness to lightness (greater L* values indicate a lighter color); a* = measures redness (greater a* values indicate a redder color; and b* =

measures yellowness (greater b* values indicate a more yellow color).5Japanese fat color standards (1 = creamy white to 4 = pinkish white; The Japan Ham & Sausage Processors Cooperative Assoc., Shibuya-ku, Tokyo, Japan).

Figure 1. Quadratic slope differences (P = 0.04) between feeding dura-tions of dietary beef tallow (BT; R2 = 0.0003; RMSE = 0.966) and yellow grease (YGr; R2 = 0.0032; RMSE = 0.986) on Japanese fat color scores (1 = creamy white to 4 = pinkish white; The Japan Ham & Sausage Processors Cooperative Assoc., Shibuya-ku, Tokyo, Japan).


Belly Fatty Acid Composition

Proportions of all SFA, including myristic (14:0), pentadecanoic (15:0), palmitic (16:0), margaric (17:0), stearic (18:0), and arachidic (20:0) acids, were not (P ≥ 0.06) affected by the fat source fed during the last 2 feeding phases (YG45 vs. BT45), and feeding YGr during the last 3 phases increased (P = 0.05) only 20:0 percentages in belly s.c. fat (Table 4). However, bellies from BT15-fed pigs had greater (P < 0.01) proportions of total SFA, in particular 14:0, 15:0, 16:0, 18:0, and 20:0, than bellies from YG15-fed pigs.

Belly fat concentrations of 15:0, 16:0, and 17:0 in-creased (linear, P ≤ 0.05), whereas percentages of 18:0 increased (quadratic, P < 0.01), with increasing time fed BT (Table 5). Conversely, the proportions of all SFA, as well as 14:0, 15:0, 17:0, and 18:0, decreased linearly (P ≤ 0.03) as the duration of dietary YGr increased from 37 to 103 d. Although fatty composition of belly s.c. fat was altered by the duration of feeding BT or YGr, nei-ther linear (P ≥ 0.07) nor quadratic (P ≥ 0.06) slopes differed between YGr and BT for total SFA, or any spe-

Table 4. Effect of phase-feeding fats on the fatty acid composition of fresh pork belly fat


SEP-value2

YG15 YG345 YG45 BT45 BT345 BT15 A B CNo. of pens 6 6 6 6 6 6Total SFA 32.27 33.29 33.09 33.52 33.30 34.03 0.267 < 0.01 0.97 0.21Palmitic acid (16:0) 20.57 21.15 21.10 21.22 21.34 21.44 0.165 < 0.01 0.35 0.58Stearic acid (18:0) 9.28 9.55 9.39 9.75 9.33 9.89 0.129 < 0.01 0.23 0.06Myristic acid (14:0) 1.41 1.54 1.53 1.50 1.58 1.57 0.024 < 0.01 0.20 0.22Pentadecanoic acid (15:0) 0.10 0.11 0.11 0.11 0.11 0.12 0.003 < 0.01 0.48 0.49Margaric acid (17:0) 0.55 0.56 0.58 0.57 0.57 0.63 0.013 < 0.01 0.62 0.80Arachidic acid (20:0) 0.17 0.17 0.16 0.16 0.16 0.16 0.004 < 0.01 0.05 0.63Total MUFA 44.94 45.27 46.20 46.11 47.10 46.56 0.322 < 0.01 < 0.01 0.83Oleic acid (18:1c9) 37.14 37.31 37.91 38.00 38.54 38.30 0.243 < 0.01 < 0.01 0.81Myristoleic acid (14:1) 0.05 0.06 0.06 0.06 0.06 0.06 0.001 < 0.01 < 0.01 0.62Palmitelaidic acid (16:1t) 0.13 0.14 0.15 0.15 0.17 0.18 0.003 < 0.01 < 0.01 0.10Palmitoleic acid (16:1c) 2.30 2.40 2.48 2.38 2.61 2.52 0.051 < 0.01 < 0.01 0.15Heptadecenoic acid (17:1t) 0.05 0.05 0.05 0.06 0.06 0.07 0.001 < 0.01 < 0.01 0.04Total 18:1t fatty acids 1.37 1.36 1.37 1.39 1.39 1.45 0.021 < 0.01 0.46 0.47Vaccenic acid (18:1c11) 3.20 3.27 3.48 3.37 3.58 3.31 0.081 0.35 0.01 0.32Gadoleic acid (20:1c11) 0.71 0.69 0.69 0.70 0.70 0.68 0.011 0.10 0.70 0.52Total PUFA 20.46 19.14 18.41 18.10 17.24 16.98 0.356 < 0.01 < 0.01 0.54Linoleic acid (18:2n-6) 17.94 16.80 16.09 15.80 15.02 14.80 0.324 < 0.01 < 0.01 0.52Total CLA 0.36 0.38 0.42 0.43 0.47 0.49 0.007 < 0.01 < 0.01 0.2518:2c9t11 0.29 0.32 0.35 0.36 0.40 0.42 0.005 < 0.01 < 0.01 0.0318:2c9c11 0.05 0.05 0.05 0.05 0.05 0.04 0.001 < 0.01 0.16 0.4318:2t9t11 0.02 0.02 0.03 0.02 0.02 0.02 0.002 0.91 0.03 0.08α-Linolenic acid (18:3n-3) 0.85 0.78 0.73 0.71 0.65 0.62 0.014 < 0.01 < 0.01 0.31γ-Linolenic acid (18:3n-6) 0.03 0.03 0.03 0.03 0.02 0.03 0.003 0.56 0.69 0.71Eicosadienoic acid (20:2) 0.66 0.61 0.59 0.59 0.55 0.53 0.009 < 0.01 < 0.01 0.84Eicosatrienoic acid (20:3n-3) 0.10 0.09 0.09 0.09 0.08 0.08 0.002 < 0.01 < 0.01 0.49Dihomo-ã-linolenic acid (20:3n-6) 0.13 0.11 0.12 0.12 0.11 0.11 0.002 < 0.01 0.70 0.84Arachidonic acid (20:4n-6) 0.29 0.27 0.27 0.27 0.26 0.26 0.007 < 0.01 0.48 0.43Docosapentaenoic acid (22:5n-3) 0.07 0.07 0.07 0.07 0.07 0.06 0.002 < 0.01 0.13 0.17Other fatty acids 2.33 2.30 2.30 2.27 2.36 2.43 0.043 0.10 0.37 0.66PUFA:SFA3 0.64 0.58 0.56 0.54 0.52 0.50 0.014 < 0.01 < 0.01 0.37Iodine value4 72.33 70.46 69.97 69.34 68.74 67.85 0.435 < 0.01 < 0.01 0.26

1YG15 = grower and fi nisher diets formulated with 4.7% yellow grease (YGr) fed during all 5 feeding phases; YG345 = diets formulated with 5.0% beef tallow (BT) during the fi rst 2 feeding phases and 4.7% YGr fed during the last 3 phases; YG45 = diets formulated with 5.0% BT fed during the fi rst 3 phases and 4.7% YGr fed during the last 2 phases; BT45 = diets with 4.7% YGr fed during the fi rst 3 phases and 5.0% BT fed during the last 2 phases; BT345 = diets containing 4.7% YGr fed during the fi rst 2 feeding phases and 5.0% BT fed during the last 3 phases; and BT15 = diets formulated with 5.0% BT fed during all 5 feeding phases.

2Probability values for the specifi c contrasts of: A = YG15 vs. BT15; B = BT vs. YGr in the last 3feeding phases (YG345 vs. BT345); and C = BT vs. YGr in the last 2feeding phases (YG45 vs. BT45).

3Total PUFA/total SFA.4(0.95 × [Σ16:1]) + (0.86 × [Σ18:1]) + (1.732 × [Σ18:2]) + (2.616 × [Σ18:3]) + (0.785 × [20:1]), where brackets indicate concentration (AOCS, 1998).

Browne et al.1516

cifi c SFA, indicating that changes in backfat SFA levels occurred at similar rates between the dietary fat sources.

Only heptadecenoic acid (17:1t) was increased (P = 0.04) by feeding BT during the last 2 phases; however, the percentages of all MUFA, as well as myristoleic (14:1), palmitelaidic (16:1t), palitoleic (16:1c), 17:1t, oleic acid (18:1c9), and cis-vaccenic (18:1c11) acids, were greater (P ≤ 0.01) in belly fat from BT345-fed than YG345-fed pigs (Table 4). Furthermore, feeding pigs BT throughout the experiment (BT15) resulted in greater (P < 0.01) con-

centrations of all MUFA, including 14:1, 16:1t, 16:1c, 17:1t, all 18:1t fatty acids, and 18:1c9, in belly s.c. fat than feeding YGr throughout the experiment (YG15).

Although percentages of all MUFA, and the primary MUFA 18:1c9, were not (P ≥ 0.06) affected by the du-ration of feeding BT-formulated diets, concentrations of 14:1, 16:1t, and 17:1t increased linearly (P < 0.01), whereas belly fat levels of 16:1c increased (quadratic, P < 0.01) and 18:1c11 decreased (quadratic, P = 0.03), as the time fed BT increased from 47 to 103 d (Table 5).

Table 5. Effect of feeding duration of beef tallow or yellow grease on the fatty acid composition of fresh pork belly fat



Total SFA3 33.52 33.30 34.03 0.245 0.10 0.21 33.29 33.09 32.27 0.286 < 0.01 0.72 0.43 0.2914:0 1.50 1.58 1.57 0.022 0.05 0.07 1.54 1.53 1.41 0.025 < 0.01 0.21 0.22 0.4315:0 0.11 0.11 0.12 0.003 0.02 0.51 0.11 0.11 0.10 0.003 0.07 0.16 0.28 0.1516:0 21.22 21.34 21.44 0.156 0.34 0.83 21.14 21.10 20.59 0.173 < 0.01 0.44 0.96 0.8417:0 0.57 0.57 0.63 0.013 < 0.01 0.23 0.56 0.58 0.53 0.013 0.03 0.15 0.13 0.0618:0 9.75 9.33 9.88 0.113 0.16 < 0.01 9.55 9.39 9.28 0.143 0.21 0.65 0.07 0.0620:0 0.16 0.16 0.16 0.004 0.61 0.60 0.17 0.16 0.17 0.004 0.14 0.06 0.36 0.27Total MUFA4 46.11 47.10 46.56 0.317 0.53 0.06 45.27 46.20 44.94 0.328 0.21 0.03 0.78 0.9614:1 0.06 0.06 0.06 0.001 < 0.01 0.19 0.06 0.06 0.05 0.001 0.09 0.23 0.52 0.8216:1t 0.16 0.17 0.18 0.002 < 0.01 0.40 0.14 0.15 0.13 0.003 < 0.01 < 0.01 0.40 0.1216:1c 2.38 2.61 2.51 0.047 0.18 < 0.01 2.39 2.48 2.30 0.055 0.12 0.12 0.15 0.2417:1t 0.06 0.06 0.07 0.001 < 0.01 0.90 0.05 0.05 0.05 0.001 < 0.01 < 0.01 0.16 0.04Total 18:1t 1.39 1.39 1.45 0.022 0.07 0.33 1.36 1.37 1.37 0.019 0.97 0.97 0.38 0.3118:1c9 37.99 38.54 38.30 0.240 0.54 0.17 37.31 37.91 37.14 0.246 0.32 0.06 0.99 0.8618:1c11 3.37 3.58 3.31 0.075 0.34 0.03 3.27 3.48 3.20 0.086 0.27 0.04 0.65 0.7220:1c11 0.70 0.69 0.68 0.012 0.27 0.89 0.69 0.69 0.71 0.010 0.12 0.89 0.82 0.97Total PUFA5 18.10 17.24 16.98 0.388 0.07 0.32 19.14 18.41 20.46 0.320 < 0.01 0.02 0.80 0.4918:2n-6 15.80 15.02 14.80 0.354 0.08 0.31 16.80 16.10 17.94 0.291 < 0.01 0.02 0.77 0.48CLA 0.43 0.47 0.49 0.006 < 0.01 0.01 0.38 0.42 0.36 0.007 < 0.01 < 0.01 0.76 0.2818:2c9t11 0.36 0.40 0.42 0.005 < 0.01 < 0.01 0.32 0.35 0.29 0.005 < 0.01 < 0.01 0.97 0.2718:2c9c11 0.05 0.05 0.04 0.001 < 0.01 0.82 0.05 0.05 0.05 0.001 0.06 0.64 0.92 0.6318:2t9t11 0.02 0.02 0.02 0.002 0.89 0.23 0.02 0.02 0.02 0.003 0.45 0.04 0.48 0.4718:3n-3 0.70 0.64 0.61 0.016 < 0.01 0.14 0.78 0.73 0.85 0.012 < 0.01 < 0.01 0.58 0.2118:3n-6 0.03 0.02 0.03 0.004 0.95 0.23 0.02 0.03 0.03 0.002 0.09 0.76 0.15 0.1820:2 0.59 0.55 0.53 0.010 < 0.01 0.19 0.61 0.59 0.66 0.008 < 0.01 < 0.01 0.87 0.5620:3n-3 0.09 0.08 0.08 0.002 < 0.01 0.17 0.09 0.09 0.10 0.001 < 0.01 < 0.01 0.95 0.3920:3n-6 0.12 0.11 0.11 0.003 0.43 0.73 0.11 0.12 0.13 0.002 < 0.01 0.66 0.69 0.9320:4n-6 0.26 0.26 0.26 0.006 0.45 0.99 0.27 0.27 0.29 0.008 0.07 0.93 0.91 0.9422:5n-3 0.07 0.07 0.06 0.002 0.27 0.69 0.07 0.07 0.07 0.002 0.08 0.57 0.65 0.52Other fatty acids 2.27 2.36 2.43 0.046 0.04 0.62 2.30 2.30 2.33 0.039 0.57 0.84 0.49 0.59PUFA:SFA6 0.54 0.52 0.50 0.015 0.06 0.60 0.58 0.56 0.64 0.014 < 0.01 0.07 0.71 0.43Iodine value7 69.34 68.74 67.85 0.458 0.03 0.86 70.46 69.97 72.33 0.410 < 0.01 0.05 0.56 0.31

1Probability values that slopes of linear and quadratic polynominal equations differ between fat sources.2Lin = linear and Q = quadratic.3Total SFA is the sum of the weight percentages of capric, lauric, myristic (14:0), pentadecanoic (15:0), palmitic (16:0), margaric (17:0), stearic (18:0), and

arachidic (20:0) acids.4Total MUFA is the sum of the weight percentages of myristoleic (14:1), palmitelaidic (16:1t), palmitoleic (16:1c), 10-trans-heptadecenoic (17:1t), all 18-car-

bon fatty acids with a single trans double bond (total 18:1t), oleic (18:1c9), vaccenic (18:1c11), and gadoleic (20:1c11) acids.5Total PUFA is the sum of the weight percentages of linoleic (18:2n-6), total conjugated linoleic (CLA; including the isomers 18:2c9t11, 18:2c9c11;

18:2c10c12; and 18:2t9t11), ã-linolenic (18:3n-6), á-linolenic (18:3n-3), eicosadienoic (20:2), dihomo-ã-linolenic (20:3n-6), eicosatrienoic (20:3n-3), arachi-donic (20:4n-6), docosapentaenoic (22:5n-3), and docosahexaenoic acids.

6Total PUFA/total SFA.7(0.95 × [Σ16:1]) + (0.86 × [Σ18:1]) + (1.732 × [Σ18:2]) + (2.616 × [Σ18:3]) + (0.785 × [20:1]), where brackets indicate concentration (AOCS, 1998).


Proportions of all MUFA, including 16:1t, 17:1t, and 18:1c11, also decreased (quadratic, P ≤ 0.04) with in-creasing time fed YGr-formulated diets. Moreover, dif-ferences between quadratic slopes (P = 0.04) indicated that the deposition of 17:1t in belly fat decreased at a greater rate the longer YGr, not BT, was included in swine diets (Fig. 2); otherwise, linear (P ≥ 0.15) and quadratic (P ≥ 0.12) slopes for MUFA did not differ be-tween durations fed BT or YGr.

Fat source fed during the last 2 feeding phases did not (P ≥ 0.17) affect percentages of all PUFA, includ-ing linoleic acid (18:2n-6), α-linolenic acid (18:3n-3), γ-linolenic acid (18:3n-6), eicosadienoic acid (20:2), eicosatrienoic acid (20:3n-3), dihomo-γ-linolenic acid (20:3n-6), arachidonic acid (20:4n-6), and docosapen-taenoic acid (22:5n-3) in belly fat samples (Table 4). Additionally, total CLA, along with the 18:2c9c11 and 18:2t9t11 isomers, did not (P ≥ 0.08) differ between pigs fed BT45 and YG45; however, belly fat from BT45-fed pigs had greater (P = 0.03) CLA 18:2c9t11 isomers than that from YG45-fed pigs. When comparing fat sourc-es fed during the last 3 feeding phases, belly fat from YG345-fed pigs had greater (P < 0.01) proportions of all PUFA, as well as 18:2n-6, 18:3n-3, 20:2, 20:3n-3, 20:3n-6, 20:4n-6, and 22:5n-3, than belly fat from BT345-fed pigs; however, total CLA, and more specifi cally the 18:2c9t11 isomer, were increased (P ≥ 0.03) by feeding BT, not YGr, during the last 3 feeding phases. Moreover, feeding YGr throughout the study (YG15) increased (P < 0.01) the percentages of 18:2n-6, 18:3n-3, 20:2, 20:3n-3, 20:3n-6, 20:4n-6, 22:5n-3, and total PUFA when com-pared with feeding BT throughout the study (BT15). On the other hand, belly fat from pigs fed BT15 had greater (P < 0.01) concentrations of total CLA and 18:2c9t11 than that from YG15-fed pigs, whereas the percentage

of the 18:2c9c11 CLA isomer was greater (P < 0.01) in belly s.c. fat from YG15-fed than BT15-fed pigs.

Proportions of 18:3n-3, 20:2, 20:3n-3, and 18:2c9c11 decreased (linear, P < 0.01), whereas the per-centages of total CLA and 18:2c9t11 increased (linear, P < 0.01), as time fed BT increased from 47 to 103 d (Table 5). Furthermore, belly fat concentrations of total PUFA, including 18:2n-6, 18:3n-3, 20:2, and 20:3n-3, increased quadratically (P ≤ 0.02) with increasing time fed YG-formulated diets. Conversely, percentages of to-tal CLA, particularly the 18:1c9t11 and 18:1t9t11 iso-mers, decreased (quadratic, P ≤ 0.04) as the duration of dietary YGr increased from 37 to 103 d. There were no differences in linear (P ≥ 0.15) or quadratic (P ≥ 0.18) slopes between feeding durations of dietary YGr and BT, implying that the rates of change in belly s.c. fat PUFA levels were not affected by 1 dietary fat source over another.

Fatty acid results of the present study are in agree-ment with several published studies where saturated fat sources were fed to growing-fi nishing pigs (Apple et al., 2007, 2011; Benz et al., 2010). Adding poultry fat (Eggert et al., 1998), choice white grease (Weber et al., 2006), or high-oil corn (Rentfrow et al., 2003) to swine diets decreased total SFA and increased total unsaturated fatty acids in fresh belly slices.

Fresh bellies from BT-supplemented pigs had the greatest percentages of total SFA and elevated levels of to-tal MUFA, including 16:1t, 16:1c, 17:1t, 18:1c9, 18:1c11, and 20:1c11, and these bellies were fi rmer and took more force to compress than those from soybean oil–fed pigs (Apple et al., 2007). More importantly, feeding diets for-mulated with soybean oil resulted in a 35% increase in the proportion of PUFA in belly fat, therefore causing bel-lies to be considerably softer than those from BT-fed pigs (Apple et al., 2007), similar to the results of the current study. Soft bellies tend to have decreased proportions of 16:0 and 18:0 and greater proportions of 18:2n-6 (Larsen et al., 2009; Leick et al., 2010), and, based on this criteria, the fatty acid composition of bellies in the present study would be indicative of borderline soft bellies.

As DDGS were increased in swine diets, fresh bellies become softer due to increased PUFA composition (Benz et al., 2010; Leick et al., 2010). In fact, the PUFA content, including 18:2n-6, 18:3n-3, 20:2, and 20:3n-6, increased linearly, whereas the SFA and MUFA content decreased linearly, with increasing dietary inclusion levels of DDGS (Xu et al., 2010b). Leick et al. (2010) also noted a shift from 18:1c9 to 18:2n-6 in the belly due to increased un-saturation from DDGS. Furthermore, when corn oil was added to swine diets to mimic the inclusion of 20 and 40% DDGS, proportions of 16:0, 18:0, and total SFA, as well as the proportions of all MUFA, decreased linearly,

Figure 2. Quadratic slope difference (P = 0.04) between feeding dura-tions of dietary beef tallow (BT; R2 = 0.1131; RMSE = 0.009) and yellow grease (YGr; R2 = 0.1371; RMSE = 0.007) for weight percentages of hep-tadeconic acid (17:1t) in belly subcutaneous (s.c.) fat samples.

Browne et al.1518

whereas the 18:3n-3 and PUFA content increased linearly, with increasing dietary corn oil (Apple et al., 2011).

The proportion of other unidentifi ed fatty acids in bel-ly s.c. fat was not (P ≥ 0.10) altered by the fat source fed during the last 2 phases, the last 3 phases, or across the en-tire 103-d feeding trial (Table 4); however, weight percent-ages of other fatty acids increased linearly (P = 0.04) with increasing time fed BT-formulated diets (Table 5). Neither PUFA:SFA (P = 0.37) nor IV (P = 0.26) of belly s.c. fat was affected by the fat source included in the phase 4 and 5 diets, but belly fat PUFA:SFA and IV were increased (P < 0.01) when YGr was included in diets fed during the last 3 phases and throughout the study (Table 4). The PUFA:SFA was not (P ≥ 0.06) affected by duration of dietary BT, but IV decreased (linear, P = 0.03) with increasing time fed BT (Table 5). Conversely, both PUFA:SFA (linear, P < 0.01) and IV (quadratic, P = 0.05) increased as the time fed YGr increased from 37 to 103 d. Also, linear and qua-dratic slopes for other fatty acids, PUFA:SFA, and IV were not (P ≥ 0.31) different between feeding durations of BT and YGr. An acceptable IV range of 70 to 75 g/100 g of fat has been suggested (Benz et al., 2010), and in the present

study, IV values ranged from 67.85 mg/g for the BT15-fed pigs to 72.33 mg/g for the YG15-fed pigs, which were within, or below, this acceptable range.

Bacon Characteristics

Fat source fed during the last 2 phases, the last 3 phases, or across the 103-d feeding trial did not (P ≥ 0.07) affect pumped and smoked belly yields or the percentage of USDA-certifi ed No. 1 slices (Table 6). Pump yields actually increased (linear, P = 0.03) as the duration of dietary BT increased from 47 to 103 d, but duration of feeding YGr did not (P ≥ 0.32) infl uence whole or sliced bacon yields (Table 7). In addition, neither linear (P ≥ 0.31) nor quadratic (P ≥ 0.31) slopes differed between BT or YGr feeding durations.

Green weight, pumped weight, pressed center weight, or smokehouse yield was not affected by feed-ing swine diets formulated with choice white grease, high-oil corn, or high-oleic, high-oil corn (Rentfrow et al., 2003). Additionally, Larsen et al. (2009) found that smokehouse and sliced bacon yields were similar among

Table 6. Effect of phase-feeding fats on bacon yields, quality characteristics, and sensory attributes


BT15 SEP-value2

YG15 YG345 YG45 BT45 BT345 A B CBacon yields, %

Pump 110.5 110.8 111.1 110.2 110.2 111.3 0.35 0.13 0.21 0.06Smokehouse 98.2 98.7 98.6 97.9 98.0 98.6 0.37 0.42 0.19 0.11No. 1 slices 83.8 84.4 82.5 82.5 83.4 83.1 1.26 0.68 0.56 0.99

Fat colorLightness (L*)3 75.38 77.53 75.15 75.96 76.48 76.48 0.969 0.38 0.40 0.52Redness (a*)3 2.22 2.07 2.81 2.25 2.36 2.41 0.209 0.51 0.33 0.06Yellowness (b*)3 8.99 8.82 8.99 8.82 8.97 8.93 0.125 0.72 0.41 0.34Cooking loss, % 73.3 74.0 73.1 74.5 74.3 73.8 0.56 0.55 0.71 0.06Shear force, kg 87.4 85.4 86.3 88.1 86.4 85.2 3.87 0.69 0.86 0.75

Sensory traitsInitial crispiness4 4.1 4.0 4.0 4.1 4.0 3.7 0.19 0.22 0.97 0.79Bacon fl avor intensity5 5.5 5.3 5.4 5.4 5.4 5.6 0.11 0.91 0.52 0.95Saltiness6 5.3 5.1 5.2 5.2 5.1 5.2 0.16 0.59 0.73 0.98Chewiness7 4.3 4.3 4.3 4.3 4.3 4.1 0.17 0.31 0.91 0.88Oiliness8 6.5 6.5 6.4 6.5 6.6 6.6 0.11 0.57 0.75 0.44Off-fl avor intensity8 7.7 7.6 7.6 7.7 7.6 7.7 0.07 0.54 0.88 0.561YG15 = grower and fi nisher diets formulated with 4.7% yellow grease (YGr) fed during all 5 feeding phases; YG345 = diets formulated with 5.0% beef tallow

(BT) during the fi rst 2 feeding phases and 4.7% YGr fed during the last 3 phases; YG45 = diets formulated with 5.0% BT fed during the fi rst 3 phases and 4.7% YGr fed during the last 2 phases; BT45 = diets with 4.7% YGr fed during the fi rst 3 phases and 5.0% BT fed during the last 2 phases; BT345 = diets containing 4.7% YGr fed during the fi rst 2 feeding phases and 5.0% BT fed during the last 3 phases; and BT15 = diets formulated with 5.0% BT fed during all 5 feeding phases.

2Probability values for the specifi c contrasts of: A = YG15 vs. BT15; B = BT vs. YGr in the last 3 feeding phases (YG345 vs. BT345); and C = BT vs. YGr in the last 2 feeding phases (YG45 vs. BT45).

3L* = measures darkness to lightness (greater L* values indicate a lighter color); a* = measures redness (greater a* values indicate a redder color; and b* = measures yellowness (greater b* values indicate a more yellow color).

41 = extremely crisp to 8 = extremely soft.51 = extremely bland to 8 extremely intense.61 = extremely bland to 8 = extremely salty.71 = extremely crumbly to 8 = extremely chewy.81 = abundant to 8 = none.


pigs consuming diets formulated with CLA, high-oil corn, or choice white grease.

Similar to fresh belly fat color, L*, a*, and b* values for the fat portion of bacon slices were not (P ≥ 0.06) affected by any dietary treatment (Table 6). Moreover, the duration of feeding YGr or BT did not (P ≥ 0.06) al-ter bacon fat color (Table 7); however, quadratic curves for bacon fat redness (a*) values differed (P = 0.02) be-tween BT and YGr feeding durations, indicating that a* values increased at a greater rate the longer YGr, not BT, was included in swine diets (Fig. 3).

Bacon cooking losses were not affected by any di-etary treatment (P ≥ 0.06; Table 6) or by BT or YGr feed-ing duration (P ≥ 0.13; Table 7). Similarly, Rentfrow et al. (2003) and Jackson et al. (2009) reported no effect of dietary oils, fats, or greases on bacon cooking losses, and bacon cooking yields were not affected by increas-ing levels of DDGS in swine diets (Leick et al., 2010; Xu et al., 2010b). Additionally, Allo-Kramer shear force was not (P ≥ 0.72) affected by phase-feeding fat in the present study (Table 6), nor were shear force values af-fected (P ≥ 0.56) by duration of either dietary BT or YGr (Table 7). The available information would indicate that feeding diets with added animal fats has no detrimen-

tal effects on shear force values of cooked LM chops (Engel et al., 2001; Jackson et al., 2009).

Sensory attributes of bacon (initial crispiness, bacon fl avor intensity, saltiness, sustained chewiness, oiliness, and off-fl avor intensity) were not (P ≥ 0.22) affected by the dietary treatments (Table 6). Even though duration of feeding YGr had no (P ≥ 0.08) effect on bacon sen-

Table 7. Effect of feeding duration of beef tallow or yellow grease on bacon yields, quality characteristics, and sen-sory attributes



Bacon yields, %Pump 110.2 110.2 111.3 0.34 0.03 0.47 110.8 111.1 110.5 0.36 0.42 0.47 0.44 0.31Smokehouse 97.9 98.0 98.6 0.37 0.17 0.86 98.7 98.6 98.2 0.36 0.32 0.79 0.89 0.76No. 1 slices 82.5 83.4 83.1 0.70 0.65 0.45 84.3 82.8 84.1 0.64 0.94 0.44 0.31 0.31

Fat colorLightness (L*)3 75.96 76.48 76.48 0.842 0.65 0.70 77.53 75.15 75.38 1.081 0.28 0.22 0.11 0.15Redness (a*)3 2.24 2.36 2.41 0.134 0.42 0.72 2.07 2.81 2.22 0.263 0.91 0.06 0.02 0.02Yellowness (b*)3 8.82 8.96 8.93 0.131 0.65 0.53 8.82 8.99 8.99 0.119 0.42 0.45 0.49 0.51Cooking loss, % 74.5 74.3 73.8 0.59 0.34 0.98 74.1 73.1 73.3 0.516 0.39 0.13 0.16 0.16Shear force, kg 88.1 86.4 85.2 3.26 0.56 0.86 85.4 86.3 87.4 4.40 0.72 0.95 0.71 0.79

Sensory traitsInitial crispiness4 4.1 4.0 3.7 0.17 0.11 0.91 4.0 4.0 4.1 0.21 0.74 0.87 0.97 0.95Bacon fl avor intensity5 5.4 5.4 5.6 0.13 0.37 0.74 5.4 5.4 5.6 0.08 0.08 0.97 0.58 0.62Saltiness6 5.2 5.2 5.2 0.19 0.81 0.98 5.0 5.2 5.3 0.14 0.26 0.55 0.53 0.57Chewiness7 4.3 4.3 4.1 0.16 0.40 0.66 4.2 4.3 4.3 0.19 0.73 0.90 0.83 0.78Oiliness8 6.5 6.6 6.6 0.10 0.78 0.81 6.5 6.4 6.5 0.12 0.86 0.56 0.52 0.53Off-fl avor intensity8 7.7 7.6 7.7 0.05 0.68 0.02 7.6 7.6 7.7 0.08 0.16 0.95 0.33 0.391Probability values that slopes of linear and quadratic polynominal equations differ between fat sources.2Lin = linear and Q = quadratic.3L* = measures darkness to lightness (greater L* values indicate a lighter color); a* = measures redness (greater a* values indicate a redder color; and b* =

measures yellowness (greater b* values indicate a more yellow color).41 = extremely crisp to 8 = extremely soft.51 = extremely bland to 8 extremely intense.61 = extremely bland to 8 = extremely salty.71 = extremely crumbly to 8 = extremely chewy.81 = abundant to 8 = none.

Figure 3. Quadratic slope difference (P = 0.02) between feeding dura-tions of beef tallow (BT; R2 = 0.0025; RMSE = 1.398) and yellow grease (YGr; R2 = 0.0461; RMSE = 1.487) for redness (a*) values of bacon fat (greater a* values indicate a redder color).

Browne et al.1520

sory attributes, off-fl avor intensity decreased (quadratic, P = 0.02) as the time fed BT increased from 47 to 103 d (Table 7). Likewise, bacon from pigs supplemented with choice white grease or poultry fat was similar to controls when evaluated for brittleness, fl avor intensity, saltiness, off-fl avor, and aftertaste (Engel et al., 2001). In addition, as DDGS inclusion in the diet was increased, trained taste panelists observed a decrease in bacon tenderness, a trend for a decrease in bacon fattiness and rancid taste, and a trend for an increase in bacon crispiness (Widmer et al., 2008). However, Xu et al. (2010b) reported that bacon fl avor, off-fl avor, crispiness, and overall accept-ability were not affected by dietary DDGS, but bacon fattiness and bacon tenderness were linearly reduced with increasing dietary DDGS.

Conclusions

Results of the current study indicate that phase-feed-ing BT (a saturated fat source) in place of YGr (a poly-unsaturated fat source) to pigs fed diets formulated with up to 30% DDGS tended to improve fresh belly fi rm-ness but had no appreciable effects on yields or qual-ity characteristics of commercially-processed bacon. Furthermore, belly fat in pigs fed BT for the entirety of the trial had greater SFA and MUFA composition and lower PUFA compared with fat in pigs fed YGr through-out the study. Additionally, belly fatty acid composition from pigs fed BT in the late fi nisher phases was more similar to fat from pigs fed BT across the entire trial; therefore, it is plausible that supplementing fi nisher diets with a saturated fat source in the latter production phases may prevent the development of poor quality pork fat, especially when grower diets are formulated with high levels of DDGS or highly unsaturated greases and oils.

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Alternating dietary fat sources for growing-ﬁ nishing pigs ...pdfs.semanticscholar.org/9c7f/93574b4cc771644b5ff0d4cfc90ce9a… · 3Corresponding author: [email protected] Received