Conjugated linoleic acid changes swine ... - MAFIADOC.COM

Conjugated linoleic acid changes swine performance and carcass composition R. L. Thiel-Cooper, F. C. Parrish, Jr, J. C. Sparks, B. R. Wiegand and R. C. Ewan J ANIM SCI 2001, 79:1821-1828.

The online version of this article, along with updated information and services, is located on the World Wide Web at: http://jas.fass.org/content/79/7/1821

www.asas.org

Downloaded from jas.fass.org by guest on May 23, 2011

Conjugated linoleic acid changes swine performance and carcass composition1 R. L. Thiel-Cooper, F. C. Parrish, Jr.2, J. C. Sparks, B. R. Wiegand, and R. C. Ewan Department of Animal Science, Iowa State University, Ames 50011

ABSTRACT: Conjugated linoleic acid (CLA) is a collective term for positional and geometric isomers of linoleic acid. Dietary CLA has been shown to improve feed efficiency, decrease body fat, and increase lean tissue in laboratory animals. We hypothesized that CLA would improve performance and carcass composition and would be deposited in pork tissues. Diets of 40 crossbred pigs were supplemented with CLA to determine its effects on performance and carcass composition. Eight replications of five littermate barrows with an initial average weight of 26.3 kg were allotted at random to individual pens. Within replication dietary treatments containing 0, 0.12, 0.25, 0.5, or 1.0% CLA were assigned at random. Pigs were weighed and feed disappearance was determined at 14-d intervals. Average daily gain increased linearly as the level of CLA increased in the diet (P < 0.05). Average daily feed intake was not affected by the concentration of CLA in the diet. Therefore, a linear increase in gain:feed ratio

(P < 0.05) was observed. Carcasses from animals fed control diets had greater 10th rib backfat than carcasses from animals fed CLA (P < 0.05). Ultrasound measurement and carcass measurements showed less fat depth over the loin eye at the 10th rib of pigs fed doses of CLA (P < 0.05) than that observed for control pigs. Belly hardness (firmness) increased linearly as the concentration of CLA in the diet increased when bellies were measured for firmness either lean side up (P < 0.001) or lean side down (P < 0.05). Loin dissection data demonstrated that CLA produced a quadratic treatment effect both for less intermuscular fat (P < 0.001) and less subcutaneous fat (P < 0.05) and a linear increase for bone (P < 0.05), although finished loin weight only tended to increase (P = 0.08). The CLA concentration increased in a linear relationship in both subcutaneous fat (P < 0.001) and lean tissue (P < 0.001). Dietary CLA was incorporated into pig tissues and had positive effects on performance and body composition.

Key Words: Body Composition, Linoleic Acid, Pork 2001 American Society of Animal Science. All rights reserved.

Introduction Conjugated linoleic acid (CLA) consists of a group of positional and geometric (cis or trans) isomers of linoleic acid. Dietary sources of CLA include milk fat, meat products, and vegetable oils. Chin et al. (1992) found CLA in a wide variety of foodstuffs, with meat and milk from ruminants having the highest content. Conjugated linoleic acid has been reported to have potent reparti-

1 Journal Paper No. 18667 of the Iowa Agric. and Home Econ. Exp. Sta., Ames, IA. Project No. 3386. This research was supported in part by State of Iowa Funds and grants from the National Pork Producers Council and the Center for Designing Foods to Improve Nutrition. Appreciation is expressed to Pharma Nutrients for supplying the CLA. Also, appreciation is expressed to Michael Pariza’s laboratory, Univ. of WI-Madison for analyzing the CLA content of the diets, and to Kevin Ragland for the real-time ultrasound measurements. 2 Correspondence: phone: 515-294-3280; fax: 515-294-5066; E-mail: [email protected]. Received June 29, 2000. Accepted March 27, 2001.

J. Anim. Sci. 2001. 79:1821–1828

tioning and feed efficiency improving effects in rats (Chin et al., 1994). Mice fed CLA were found to have significant changes in body composition, including decreased fat deposition, increased whole-body protein, and increased carcass water (Park et al., 1997). Dugan et al. (1997) reported increased lean and decreased subcutaneous carcass fat when CLA was fed to pigs. In addition, CLA has been shown to stimulate the immune system (Cook et al., 1993) and protect against chemically induced cancers (Pariza et al., 1983; Ip et al., 1994, 1997; Belury et al., 1996) and atherosclerosis (Lee et al., 1994; Nicolosi et al., 1997). Because of the recent availability of feed-grade CLA, experimentation on large animals is now possible. As a result, considerable interest for including CLA in pig feed to improve lean production efficiency and pork quality and to provide value-added healthful meat products for human consumption now exists. The objective of this study was to determine the growth performance, body composition, and tissue deposition of CLA in growing-finishing pigs fed diets containing 0, 0.12, 0.25, 0.50, or 1.0% CLA by weight of the diet.

1821 Downloaded from jas.fass.org by guest on May 23, 2011

1822

Thiel-Cooper et al.

Table 1. Fatty acid composition of the conjugated linoleic acid sourcea used for dietary supplementation Fatty acid

g/100 g oil

16:0 18:0 18:1 18:2

4.6 3.4 23.8 7.7

Total CLA isomersb c9, tll and t9, cll t10, c12 t9, t11 and t10, t12 c8, t10 and t8, c10 c9, c11 c11, t13 and t11, c13 c8, c10 c10, c12 c11, c13 other

12.3 14.0 5.2 8.3 1.3 12.2 0.5 2.1 0.4 4.2

a

Synthesized by Pharma Nutrients, Oak Brook, IL. c = cis, t = trans.

b

Materials and Methods Animals and Diets Eight replications of five littermate barrows (Yorkshire × Landrace × Duroc × Hampshire) with an average initial BW of 26.3 kg were allotted at random to individual pens. Within replication, treatments of diets containing 0, 0.12, 0.25, 0.50, or 1.0% CLA were assigned at random. The CLA source (Pharma Nutrients, Oak Brook, IL) contained 60.5% CLA (Table 1) and was added to the diets at concentrations of 0.20, 0.42, 0.83, or 1.67% to provide the desired concentration of CLA. The CLA was substituted for corn. The diets were initially formulated to contain 18.7% crude protein and 1.0% lysine (Table 2). Diets were reformulated at 3-wk

Table 2. Composition of the basal experimental diet fed to growing-finishing pigs Ingredient Ground corna Dehulled soybean meal Dicalcium phosphate Calcium carbonate Salt Vitamin premixb Mineral premixc Antimicrobiald

% 70.13 27.13 1.28 0.86 0.25 0.20 0.05 0.10

a CLA source (60% CLA) was substituted for corn in the diet. Diets containing 0.12% CLA included 69.93% corn, 0.25% CLA included 69.71% corn, 0.50% CLA included 69.30% corn, and 1.0% CLA included 68.46% corn. b Contributed the following per kilogram of diet: 2,222 IU of vitamin A, 550 IU of vitamin D3, 11 ␮g of vitamin B12, 3.3 mg of riboflavin, 8.8 mg of D-pantothenic acid, and 16.5 mg of niacin. c Contributed the following per kilogram of diet: 99 mg of Zn, 49.9 g of Fe, 5.5 mg of Cu, 27.5 mg of Mn, and 74.8 mg of I. d Contributed 88 mg tylosin per kilogram of diet.

intervals (six formulations) to reduce crude protein and lysine content to 12.3 and 0.55%, respectively, in the final finishing stage to meet NRC requirements. Room temperature was maintained at about 18 to 21°C. Pigs were allowed ad libitum access to feed and water. Individually housed pigs were weighed and feed disappearance was determined at 14-d intervals.

Body and Carcass Composition Ultrasound was used to determine backfat thickness and loin eye area (LEA) at approximately 52, 68, 91, and 114 kg BW. These measurements were used to determine at what live weight control and CLA-fed pigs first exhibited differences in backfat thickness and LEA. Scanning was accomplished with an ALOKA 500V (Corometrics Medical Systems, Wallingford, CT) realtime ultrasonic machine fitted with a 12.5-cm long, 3.5MHz linear array transducer. Ultrasound measurements were taken along the dorsal midline at the 10th rib. The transducer was aligned perpendicular to the spine at the 10th rib. Digitized images were interpreted using Quality Evaluation and Prediction (Iowa State University, Ames), a computer software package developed specifically to measure linear distance and area of digitized images and matriculate to a data file. Tenthrib fat depth was measured at a point three-quarters of the distance of the loin muscle, curvilinear from the spine, and perpendicular to the loin muscle surface. Pigs were slaughtered when the average weight of littermates was 116 kg according to humane slaughter requirements at the Iowa State University Meat Laboratory. After slaughter, the carcasses were chilled for 24 h at −2 to 0°C. Sides were ribbed between the 10th and 11th rib and LEA was measured at the 10th–11th rib interface to the nearest tenth of a square centimeter using a plastic grid. Fat depth measurements were made to the nearest 0.25 of a centimeter at the 1st (along split backbone), 10th (fat over the loin eye, ³⁄₄ of the length of the eye from the bone side), and last ribs and the last lumbar vertebrae (along split backbone) using a steel ruler. Total loin dissection was done and primal to wholesale-ready cut measurements were taken. The primal loin from the right side of each carcass was dissected into component parts (lean, subcutaneous fat, intermuscular fat, bone, skin, and trim), and weights of each were recorded in kilograms. Each primal cut from the left side of the carcass (ham, loin, picnic, and butt) was then trimmed to 0.64 cm external fat wholesale-ready product. Bellies were skinned and squared and spareribs were removed in preparation for bacon production. Weights of component parts (initial, trim, and finished) were measured in kilograms. Belly hardness (firmness) was determined by suspending the longitudinal midpoint of the belly across a stainless steel rod and measuring the distance in centimeters between the ham and shoulder end, both lean side up and lean side down.


1823

CLA effects on pork composition

Table 3. Growth performance of growing-finishing pigs fed diets containing varying levels of conjugated linoleic acid % Dietary CLA added Item

0

ADG, kg ADFI, kg Gain/feed

0.12 b

0.942 2.683 0.352b

b

0.930 2.538 0.367ab

0.25 b

0.953 2.556 0.373ab

0.50 ab

0.974 2.633 0.370ab

1.0

SEM a

1.019 2.634 0.384a

0.183 0.052 0.008

Values with different superscripts within a row indicate linear treatment effects (P < 0.05).

a,b,c

Lipid Analysis

Results and Discussion

Lipids in the loin lean tissue and subcutaneous fat samples (1.27 cm thick at the 9th–10th rib interface) were extracted in triplicate by using the modified Folch et al. (1957) method, with chloroform/methanol (2:1, vol/vol). Lipids extracted from tissue samples were methylated (sodium methoxide) as described by Li and Watkins (1998): 2 mg of sample was dissolved in hexane (1 mL) in a test tube with a Teflon-lined screw cap, 0.5 M sodium methoxide in anhydrous methanol (2 mL) was added, the solution was maintained at 50°C for 10 min, and glacial acetic acid (0.1 mL) was added, followed by deionized water (5 mL). The fatty acid methyl esters (FAME) were extracted into hexane (2 × 3 mL) and dried over anhydrous sodium sulfate. All FAME were analyzed using a gas chromatograph (HP 6890, autosampler 6890; Hewlett-Packard Co., Avondale, PA) equipped with an HP 19091J-413 column (30 m, 320 ␮m i.d., 0.25 ␮m film thickness; Hewlett-Packard, Avondale, PA) and operated at 180°C for 0.5 min (temperature programmed 2°C/min to 230°C and held for 4.50 min). The injector and flame-ionization detector (FID) temperatures were both set at 300°C. The FAME were identified by comparison of their retention times with an authentic standard (UC-59 MX, Nu-CheckPrep, Elysian, MN) and were verified with mass spectophotometry. The ionization potential of mass selective detector (Model 5973, Hewlett Packard, Wilmington, DE) was 70 eV, scan range was 50 to 550 m/z, and scan velocity was 2.94 scan/s. The identification of volatiles was achieved by comparing mass spectral data with those of the Wiley library (Hewlett Packard, Wilmington, DE). The gas chromatograph oven temperature and column conditions were the same as in the FID analysis.

Statistical Analysis Data were analyzed with the GLM procedures of SAS (SAS Inst. Inc., Cary, NC) with the pig as the experimental unit. One pig was removed from the test due to lameness, therefore n = 39. General linear models included main effects for treatment and replication. Treatment effects were partitioned into linear and quadratic responses by orthogonal contrasts. Slaughter weight (114 kg) was included as a covariate for all analyses.

Pig performance (Table 3) as measured by ADG increased linearly (P < 0.01) as the concentration of CLA in the diet increased. The greatest difference was at the 1.0% level compared with the controls, and these results suggested that even greater amounts of CLA in the diet might have yielded even greater increases in ADG. The ADG for all pigs fed CLA diets was slightly suppressed during the first 2 wk of the study. After wk 2, however, the ADG of CLA-fed pigs tended to be greater than that of controls when measured at 2-wk intervals. Pigs initially required adjustment time to any addition of CLA in their diet. Results on ADG reported in other studies have varied. Park et al. (1997) found no difference in ADG for male mice, but there was a slight decrease in ADG for females. In pigs, Dugan et al. (1997) found no differences in ADG between pigs fed CLA and pigs fed sunflower oil. Dunshea et al. (1998) described a trend toward increased ADG, whereas Cook et al. (1998) described a decrease in ADG from d 0 to 49 for CLA-fed pigs. With respect to ADG changes, it is difficult to explain differences between the current study and the work of others because the numbers of variables for which we must account are too numerous (e.g., sex, season, and breed type). There was also a slight suppression of feed intake for CLA-fed pigs during the first 2 wk. This supported a slight decrease in ADG seen during the same period. From wk 2 on, there was no difference in feed intake (P = 0.85). Increased gain/feed (P < 0.01) resulted from increased ADG without an increase in ADFI. No difference in feed intake was noted in rats by Chin et al. (1994). However, Park et al. (1997) demonstrated that intake was reduced during the first 15 d of a study with mice. Dugan et al. (1997) reported decreased feed intake from 60 to 105 kg live weight and Cook et al. (1998) reported decreased feed intake from 0 to 49 d for pigs. In Table 4, data indicate 10th rib fat depth from CLAtreated pork carcasses was lower than 10th rib fat depth of controls (P < 0.05) in a quadratic relationship. No other fat depth measurements (first rib, last rib, or last lumbar) exhibited a treatment difference at any level of CLA supplementation. First-rib backfat tended to decrease linearly (P = 0.07), as demonstrated by a −3.91% difference at 0.12% CLA addition and −15.65% at 1.0% CLA addition. Last rib and last lumbar fat


1824

Thiel-Cooper et al.

Table 4. Dietary conjugated linoleic acid effects on fat depth and loin eye area of live animals (ultrasound) and carcasses % Dietary CLA added Item First-rib fat depth, cm Last-rib fat depth, cm Last-lumbar fat depth, cm Tenth-rib fat depth, cm Loin eye area, cm2 Ultrasound backfat, cm Ultrasound loin eye area, cm2

0

0.12

0.25

0.50

1.0

SEM

4.08 2.61 2.41 2.86a 41.22ab 2.44a 42.6a

3.93 2.85 2.42 2.34b 43.85a 2.15b 43.7a

3.53 2.49 2.38 2.34b 42.03ab 2.16b 45.6ab

3.78 2.51 2.37 2.61ab 40.08ab 2.28ab 44.9ab

3.45 2.69 2.59 2.57ab 39.28b 2.37ab 47.2b

0.22 0.22 0.19 0.16 1.35 0.10 1.24

Values with different superscripts within a row indicate quadratic treatment effects (P < 0.05).

a,b,c

depth results indicated no differences between treatments and controls. Ultrasound backfat results over time demonstrated a quadratic effect for treatment. Fat depth decreased at approximately 91 kg of live weight for pigs on the 0.12% CLA treatment compared with controls. This difference (P < 0.001) was maintained at 114 kg for the 0.12 and 0.25% CLA treatments (Figure 1). The 10th rib fat depth results of carcasses confirmed 10th-rib ultrasound measurement results of live animals (Table 4). Cook et al. (1998) reported ultrasound backfat differences of 26% by the end of the feeding period for pigs fed 0.95% CLA and actual 10th-rib backfat at slaughter was 24.2% less than that of controls.

Figure 1. Effect of dietary conjugated linoleic acid (CLA) (0 = control, 0.12 = 0.12% CLA, 0.25 = 0.25% CLA, 0.50 = 0.50% CLA, 1.0 = 1.0% CLA) on 10th-rib fat depth (cm) of growing-finishing pigs measured by using ultrasound. a,b,cValues with different superscripts within a weight category indicate linear treatment effects (P < 0.05).

Our ultrasound LEA results (Figure 2) also indicated an increase in LEA for 1.0% CLA treatments at approximately 91 and 114 kg compared with controls. Ultrasound LEA results showed a linear effect of treatment with increased concentration of CLA in the diet at 91 and 114 kg. This result was not supported, however, by carcass LEA measurements, which indicated no difference between controls and pigs fed CLA. In fact, results indicated a decreased trend for LEA with increased CLA concentration (Table 4). Cook et al. (1998) also reported no differences between controls and treated pigs for measured loin eye area. Initial loin weight (Table 5) demonstrated a quadratic effect of treatment (P < 0.05); controls and pigs fed 1.0% CLA had higher initial weights than pigs fed 0.12 or

Figure 2. Effect of dietary conjugated linoleic acid (CLA) (0 = control, 0.12 = 0.12% CLA, 0.25 = 0.25% CLA, 0.50 = 0.50% CLA, 1.0 = 1.0% CLA) on loin eye area (cm2) of growing-finishing pigs, measured by using ultrasound. a,b,c Values with different superscripts within a weight category indicate linear treatment effects (P < 0.05).



Table 5. Loin dissection component weights, means, standard error, and P-values from growing-finishing pigs fed varying amounts of conjugated linoleic acid Component and % dietary CLA added

Means, kg

SEM

P-value

11.26ab 10.89a 10.68a 11.54ab 11.89b

0.31 0.31 0.31 0.34 0.31

0.04z

Intermuscular fat, kg 0 0.12 0.25 0.50 1.0

0.25d 0.15bc 0.20bd 0.22d 0.27ad

0.02 0.02 0.02 0.03 0.02

0.005z

Subcutaneous fat, kg 0 0.12 0.25 0.50 1.0

2.86 2.37 2.39 2.62 2.84

0.19 0.19 0.19 0.20 0.19

0.03z

Bone, kg 0 0.12 0.25 0.50 1.0

1.56ab 1.56ab 1.46b 1.73a 1.71a

0.06 0.06 0.06 0.07 0.06

0.03y

Finished loin, kg 0.0 0.12 0.25 0.50 1.0

6.58 6.80 6.81 6.96 7.07

0.13 0.13 0.13 0.14 0.13

0.08y

Initial Loin, kg 0 0.12 0.25 0.50 1.0

a,b,c,d Values with different superscripts within a column and category indicate treatment effects (P < 0.05). y Linear effects of treatment. z Quadratic effects of treatment.

0.25% CLA. Less intermuscular fat was found in pigs fed 0.12% CLA than in controls or in those fed 0.50 or 1.0% CLA. Although there was a quadratic effect of treatment (P < 0.05) for subcutaneous fat, there were no individual between-treatment differences. There was a linear trend (P = 0.08) for increased finished loin weight. In general, these loin dissection data suggest that loins from pigs fed 0.12 or 0.25% CLA were lighter initially. However, less trimmable fat (both intermuscular and subcutaneous) made their finished loin weights heavier than those of controls. Dugan et al. (1997) reported increased initial loin weight and decreased subcutaneous fat and intermuscular fat in pigs fed 0.50% CLA. Cook et al. (1998) dissected the loin section between the 6th and 10th ribs only and determined that the amount of lean increased (P < 0.001) by 10% in CLA60-fed pigs. An increase in bone weight was observed (P < 0.05), and pigs fed 0.50 or 1.0% CLA had more bone than did controls or pigs fed 0.12 or 0.25% CLA. Increased cortical bone formation was demonstrated in chicks fed

1825

butter (a high source of CLA) by Watkins et al. (1997). Li and Watkins (1998) determined that CLA (1.0%) lowered ex vivo PGE2 production in bone organ cultures, suggesting that CLA has the potential to positively influence bone formation and resorption. Our loin dissection data showed that levels up to 0.50% CLA positively affected loin composition; consequently, there seemed to be a limiting effect in place by 1.0%. Within individual wholesale-ready cuts, initial (primal) cut weight for ham increased linearly (P < 0.05), as did ham trim (P < 0.05), and the 1.0% CLA treatment results were different from those for controls. No differences were observed in finished (wholesale) ham weight (Table 6). Initial loin weight and finished loin weight were not different; however, loin trim was quadratic (P < 0.05); loins from pigs fed 0.25% or 0.50% CLA had less trim than did those from controls. Initial picnic weights (P < 0.05) and picnic trim weights (P < 0.01) increased linearly; those from 1.0% CLA-treated pigs were different from those from control pigs. Combined, these produced no difference in finished picnic weight. Although no differences in either initial butt weight or butt trim weight were observed, there was a linear increase in finished butt weight (P < 0.05), and the 1.0% CLA treatment was different from the control. Initial belly weight (P < 0.001) and finished belly weight (P < 0.001) increased linearly, with 1.0% CLA different from the controls. Belly trim exhibited a quadratic effect of treatment (P < 0.001); and bellies from pigs fed 0.12 or 0.25% CLA had more trim than did those from controls or pigs fed 0.50 or 1.0% CLA. The most obvious difference observed during the primal to wholesale-ready portion of the experiment was the hardness (firmness) of the belly. When belly firmness was measured lean side up (Figure 3), a linear effect of treatment (P < 0.001) was observed with increasing amounts of CLA, and firmer bellies were found at 0.50 and 1.0% CLA. A similar linear effect of treatment was observed (P < 0.05) when bellies were measured lean side down (Figure 4). Firmer bellies provide a potential for improvement in sliceability and increase in yield of bacon. Cook et al. (1998), using the same measurement, also demonstrated an increase in belly firmness. Our observation of increased belly firmness could be explained by an increase in the ratio of saturated:unsaturated fatty acids composition of bellies. Our fatty acid data of subcutaneous fat of loins (Table 7) supported the increase in belly firmness by showing that saturated fatty acids increased with an increase in dietary CLA. We have assumed that the change in fatty acid profile of bellies would be similar to that of subcutaneous fat of loins. Indeed, in a subsequent study (unpublished observations; Wiegand et al., 2000), we found that the changes in fatty acid composition as affected by dietary CLA for subcutaneous fat and belly fat were similar. Based on work reported by Lee et al. (1988), CLA affects the saturated:unsaturated fatty acid ratio by inhibiting stearoyl-CoA desaturase activity, a key enzyme involved in the synthesis of monoun-


1826

Thiel-Cooper et al.

Table 6. Weights, means, standard errors, and P-values for primal cuts trimmed to wholesale-ready product from growing-finishing pigs fed varying amounts of conjugated linoleic acid Primal wt, kg Cut and % CLA

Wholesale wt, kg

Mean

SE

P-value

Initial ham 0 0.12 0.25 0.50 1.0

10.08a 10.18ab 10.33ab 10.55ab 10.94b

0.28 0.28 0.28 0.30 0.28

0.02

Initial loin 0 0.12 0.25 0.50 1.0

11.71 11.57 11.64 11.57 12.09

0.38 0.38 0.38 0.41 0.38

0.53

Initial picnic 0 0.12 0.25 0.50 1.0

4.65a 4.81ab 2.76ab 4.94ab 5.12b

0.14 0.14 0.14 0.15 0.14

0.03

Initial butt 0 0.12 0.25 0.50 1.0

4.49 4.53 4.54 4.49 4.79

0.15 0.15 0.15 0.16 0.15

0.23

Initial belly 0 0.12 0.25 0.50 1.0

7.96a 8.02a 8.53ab 8.36ab 8.99b

0.24 0.24 0.24 0.26 0.24

0.004

Trim wt, kg

Cut and % CLA

Mean

SE

P-value

Finished ham 0 0.12 0.25 0.50 1.0

7.56 7.73 7.88 7.99 8.20

0.25 0.25 0.25 0.28 0.25

0.07

Finished loin 0 0.12 0.25 0.50 1.0

8.06 8.31 8.64 8.57 8.77

0.29 0.29 0.29 0.32 0.29

0.08

Finished picnic 0 0.12 0.25 0.50 1.0

2.64 2.79 2.82 2.78 2.85

0.12 0.12 0.12 0.13 0.12

0.30

Finished butt 0 0.12 0.25 0.50 1.0

2.46ab 2.34a 2.44ab 2.52ab 2.69b

0.10 0.10 0.10 0.11 0.10

0.05

Finished belly 0 0.12 0.25 0.50 1.0

5.20a 4.90a 5.16a 5.39ab 5.92b

0.20 0.20 0.20 0.22 0.20

0.006

Cut and % CLA

Mean

SE

P-value

Ham trim 0 0.12 0.25 0.50 1.0

2.48ac 2.42a 2.40a 2.52c 2.69bc

0.08 0.08 0.08 0.08 0.08

0.04

Loin trim 0 0.12 0.25 0.50 1.0

3.66a 3.25ab 2.98b 2.99b 3.31ab

0.22 0.22 0.22 0.24 0.22

0.05z

Picnic trim 0 0.12 0.25 0.50 1.0

2.00a 2.04a 1.93a 2.13ab 2.28b

0.08 0.08 0.08 0.08 0.08

0.01

Butt trim 0 0.12 0.25 0.50 1.0

1.97 2.15 2.25 1.98 2.08

0.10 0.10 0.10 0.11 0.10

0.89

Belly trim 0 0.12 0.25 0.50 1.0

2.55a 3.03ab 3.37b 2.93a 2.77a

0.16 0.16 0.16 0.18 0.16

0.003z

Values with different superscripts within a column category indicate treatment effects (P < 0.05). Indicates quadratic effects of treatment.

a,b,c,d z

Figure 3. belly firmness measured between the shoulder and ham ends (cm) lean side up as affected by dietary conjugated linoleic acid. a,b,cValues with different superscripts indicate linear treatment effects (P < 0.007).

Figure 4. Belly firmness measured between the shoulder and ham ends (cm) lean side down as affected by dietary conjugated linoleic acid. a,bValues with different superscripts indicate linear treatment effects (P < 0.05).


1827


Table 7. Fatty acid profile of subcutaneous fat and lean tissue of pigs fed varying amounts of CLAa Fatty acid, relative % Component and % dietary CLA

20:4

c9,t11 andt11,c9b CLA

t10,c12 CLA

t9,t11 CLA

t10,t12 CLA

14:0

16:0

16:1

18:0

18:1

18:2

Subcutaneous fat 0 0.12 0.25 0.50 1.0 Pooled SEM

1.76d 1.84e 1.79d 1.90e 2.12e 0.06

30.63d 27.12de 31.63d 24.77e 20.41e 1.43

1.93d 2.32ef 2.50f 2.33ef 1.96de 0.14

12.87 13.86 12.29 13.73 12.34 0.81

25.80d 27.44e 29.42f 30.97g 31.51g 0.50

16.71d 17.47d 19.42e 20.24e 20.24e 0.50

0.15 0.17 0.14 0.15 0.16 0.01

ndcd 0.33e 0.81f 1.21g 2.16h 0.08

ndd 0.19e 0.44f 0.99g 1.87h 0.46

ndd ndd ndd 0.15e 0.35f 0.16

ndd ndd ndd 0.26e 0.47f 0.12

Lean tissue 0 0.12 0.25 0.50 1.0 Pooled SEM

1.00d 1.04de 1.16ef 1.19f 1.34g 0.04

21.81d 22.75de 24.10ef 24.94f 25.61g 0.05

2.72d 3.10de 3.31e 3.34e 4.43f 0.17

12.40 11.69 11.15 11.89 11.44 1.69

35.85df 37.17d 35.67df 33.96de 32.11e 1.12

11.99d 12.03d 12.88de 13.87e 13.01de 0.44

1.45d 1.51d 1.29de 1.06f 1.10ef 0.08

0.03d 0.08d 0.19e 0.26f 0.37g 0.02

ndd 0.04d 0.14e 0.19e 0.32f 0.02

ndd ndde 0.03ef 0.04f 0.05f 0.007

ndd ndd 0.03de 0.04ef 0.06f 0.01

a

Values are arithmetic means for eight observations. c = cis, t = trans. c nd (not detected) levels were below the detection level of 0.04%. d,e,f,g,h Values with different superscripts within a column category indicate linear effects of treatment (P < 0.01). b

saturated fatty acids and their regulation. Moreover, Bretillon et al. (1999) reported that individual CLA isomers, especially t10, c12-18:2, decreased desaturase activity in hepatic microsomes in vitro, resulting in higher concentrations of saturated fatty acids. Consequently, we believe firmer pork bellies are the result of a higher ratio of saturated:unsaturated fatty acids in belly fat and of an inhibition of the ⌬9 fatty acid desaturase in the adipose tissue by CLA. Results of CLA as a percentage of total lipids shown in Table 7 indicated that CLA isomers, especially c9, t11 and t 11, c9, were incorporated into both subcutaneous fat and lean tissue in increasing concentrations with increasing amounts of CLA in the diet. Cook et al. (1998) and Kramer et al. (1998) both reported that CLA was incorporated into tissues in a dose-dependent manner. Incorporation of CLA isomers in tissues is supported also by the work of Chin et al. (1994), Park et al. (1997), and Sugano et al. (1997). Specifically, Ha et al. (1990) and Yi-Chia Huang et al. (1994) have demonstrated that CLA was incorporated into the phospholipid fraction. Moreover, inclusions of CLA isomers into liver, heart, inner backfat, and omental fat of pigs have been reported by Kramer et al. (1998). Our results of the effects of CLA on fatty acid composition of loin subcutaneous fat and lean tissue are shown in Table 7. Lean tissue of pigs fed CLA had increased myristate (14:0) (P < 0.01) and palmitate (16:0) (P < 0.01) and decreased oleate (18:1) (P < 0.01) and arachiadonate (20:4) (P < 0.01). Increased 14:0 and 16:0 and decreased 18:1 in lean tissue indicated a shift to a higher saturated:unsaturated fatty acid ratio. Subcutaneous fat of pigs fed CLA had increased 14:0 (P < 0.01), 18:1 (P < 0.01), and 18:2 (P < 0.01) and decreased 16:0 (P < 0.01). The increase in the saturated fatty acids 14:0 and 16:0 found in lean, and 14:0 in subcutaneous fat, are

very likely due to the putative inhibition of desaturase activity by CLA. Lee et al. (1998) and Bretillon et al. (1999) in studies designed to determine the effects of CLA isomers on desaturase activity demonstrated that CLA isomers inhibited desaturase activity, and thus caused an increase in the saturated fatty acid content. Regarding changes in the saturated fatty acid profile of subcutaneous fat, the increase of 18:1 and 18:2 could have been due to the contribution of CLA-60 in the diet. CLA-60 was substituted for corn, and because CLA-60 contains high levels of unsaturated fatty acids, the diet would have been higher in unsaturated fatty acids than would a corn diet alone. In earlier work, Banni et al. (1996) and Sebedio et al. (1997) suggested that the metabolites of CLA may be elongated and desaturated, thus competing with other compounds to directly affect fatty acid composition. Turek et al. (1998) indicated that CLA fed to rats increased total spleen monounsaturated fatty acids but also increased the concentration of (n3) polyunsaturated fatty acids. The decrease in 16:0 in subcutaneous fat could be due to dietary fat causing decreases in de novo fatty acid synthesis (St. John et al., 1987). Palmitate is the major end product of fatty acid synthesis. In summary, dietary supplementation of CLA improved average daily gain and gain/feed in pigs fed from 26 to 114 kg. This improvement directly decreased the amount of feed required to finish pigs. Unlike the linear effect of CLA on performance, carcass fat measurements decreased quadratically. This relationship suggests that the amount of carcass fat is decreased the most at dietary CLA levels of 0.50% or less. Belly firmness increased dramatically by addition of CLA to the diet because of a shift toward higher concentrations of saturated fatty acids and lower concentrations of unsaturated fatty acids. Incorporation of CLA isomers


1828

Thiel-Cooper et al.

into the fatty acid profile of pork subcutaneous and lean tissues could mean potentially more healthful pork products. Further study to define the most appropriate dose required to optimize pig performance, economy of gain, and body composition must be accomplished to assist in the practical application of CLA in pig diets. Also, identifying the active isomer(s), mechanism of biological activity, and impact on human health are further areas of creative investigation.

Implications The increase in average daily gain without an increase in average daily feed intake demonstrated by supplementation with conjugated linoleic acid could save feed in the growing-finishing phase for pigs in the United States. Decreased fat deposition and increased firmness of bellies should produce less waste from trim and improved bacon sliceability and yield. The incorporation of conjugated linoleic acid into lean tissues should positively affect the health of consumers. Further study to define the most appropriate dose requirement to optimize pig performance and body composition must take place. Also, the active isomer(s) and mechanism of biological activity must be identified.

Literature Cited Banni, S., G. Carta, M. S. Contini, E. Angioni, M. Deiana, M. A. Dessi, M. P. Melis, and F. P. Corongiu. 1996. Characterization of conjugated diene fatty acids in milk, dairy products, and lamb tissues. J. Nutr. Biochem. 7:150–155. Belury, M. A., K. P. Nickel, C. E. Bird, and Y. Wu. 1996. Dietary conjugated linoleic acid modulation of phorbol ester skin tumor promotion. Nutr. Cancer 26:149–157. Bretillon, L., J. M. Chardigny, S. Gregiore, O. Berdequx, and J. L. Sebedio. 1999. Effects of conjugated linoleic acid isomers on the hepatic microsomal desaturation activities in vitro. Lipids 34:965–969. Chin, S. F., W. Liu, J. M. Storkson, Y. L. Ha, and M. W. Pariza. 1992. Dietary sources of conjugated linoleic dienoic isomers of linoleic acid, a newly recognized class of anticarcinogens. J. Food Compos. Anal. 5:185–197. Chin, S. F., J. M. Storkson, K. J. Albright, M. E. Cook, and M. W. Pariza. 1994. Conjugated linoleic acid is a growth factor for rats as shown by enhanced weight gain and improved feed efficiency. J. Nutr. 124:2344–2349. Cook, M. E., D. L. Jerome, T. D. Crenshaw, D. R. Buege, M. W. Pariza, K. J. Albright, S. P. Schmidt, J. A. Scimeca, P. A. Lofgren, and E. J. Hentges. 1998. Feeding conjugated linoleic acid improves feed efficiency and reduces carcass fat in pigs FASEB J. 11:3347. Cook, M. E., C. C. Miller, Y. Park, and M. W. Pariza. 1993. Immune modulation by altered nutrient metabolism: Nutritional control of immune-induced growth depression. Poult. Sci. 72:1301–1305. Dugan, M. E. R., J. L. Aalhus, A. L. Schaefer, and J. K. G. Kramer. 1997. The effect of conjugated linoleic acid on fat to lean repartitioning and feed conversion in pigs. Can. J. Anim. Sci. 77:1045–1050. Dunshea, F. R., E. Ostrowska, M. Muralitharan, R. Cross, D. E. Bauman, M. W. Pariza, and C. Skarie. 1998. Dietary conjugated linoleic acid decreases back fat in finisher gilts. J. Anim. Sci. 76:(Suppl. 1):508 (Abstr.).

Folch, J., M. Lees, and G. N. Sloan-Stanley. 1957. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:497–509. Ha, Y. L., J. Storkson, and M. W. Pariza. 1990. Inhibition of benzo(a)pyrene-induced mouse forestomach neoplasia by conjugated dienoic derivatives of linoleic acid. Cancer Res. 50:1097–1101. Ip, C., C. Jiang, H. J. Thompson, and J. A. Scimeca. 1997. Retention of conjugated linoleic acid in the mammary gland is associated with tumor inhibition during the post-initiation phase of carcinogenesis. Carcinogenesis 18:755–759. Ip, C., M. Singh, H. J. Thompson, and J. A. Scimeca. 1994. Conjugated linoleic acid suppresses mammary carcinogenesis and proliferative activity of the mammary gland in the rat. Cancer Res. (Oxf.) 54:1212–1215. Kramer, J. K. G., N. Sehat, M. E. R. Dugan, M. M. Mossoba, M. P. Yurawecz, J. A. G. Roach, K. E. Eulitz, J. L. Aalhus, A. L. Schaefer, and Y. Ku. 1998. Distributions of conjugated linoleic acid (CLA) isomers in tissue lipid classes of pigs fed a commercial CLA mixture determined by gas chromatography and silver ionhigh-performance liquid chromatography. Lipids 33:549–558. Lee, K. N., D. Kritchevsky, and M. W. Pariza. 1994. Conjugated linoleic acid and atherosclerosis in rabbits. Atherosclerosis 108:19–25. Lee, K. N., J. M. Ntambi, and M. W. Pariza. 1998. Conjugated linoleic acid decreases hepatic stearoyl-Co A desaturase mRNA expression. Biochem. Biophys. Res. Commun. 248:817–821. Li, Y., and B. A. Watkins. 1998. Conjugated linoleic acids alter bone fatty acid composition and reduces ex vivo prostaglandin E2 biosynthesis in rats fed n-6 or n-3 fatty acids. Lipids 33:417–425. Nicolosi, R. J., E. J. Rogers, D. Kritchevsky, J. A. Scimeca, and P. J. Huth. 1997. Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atherosclerosis in hypercholesterolemic hamsters. Artery 22:266–277. Pariza, M. W., L. J. Loretz, J. M Storkson, and N. C. Holland. 1983. Mutagens and modulator of mutagenesis in fried ground beef. Cancer Res. 43:2444S–2446S. Park, Y., K. J. Albright, W. Lui, J. M. Storkson, M. E. Cook, and M. W. Pariza. 1997. Effect of conjugated linoleic acid on body composition in mice. Lipids 32:853–858. Sebedio, J. L., P. Juaneda, G. Dobson, I. Ramilison, J. C. Martin, J. M. Chardigny, and W. W. Christie. 1997. Metabolites of conjugated linoleic isomers of linoleic acid (CLA) in the rat. Biochim. Biophys. Acta 1345:5–10. St. John, L. C., C. R. Young, D. A. Knabe, L. D. Thompson, G. T. Schelling, S. M. Grundy, and S. B. Smith. 1987. Fatty acid profiles and sensory and carcass traits of tissues from steers and swine fed an elevated monosaturated fat diet. J. Anim. Sci. 64:1441–1447. Sugano, M., A. Tsujita, M. Yamasaki, K. Yamada, I. Ikeda, and D. Kritchevsky. 1997. Lymphatic recovery, tissue distribution, and metabolic effects of conjugated linoleic acid in rats. J. Nutr. Biochem. 8:38–43. Turek, J. J., Y. Li, I. A. Schoenlein, K. G. D. Allen, and B. A. Watkins. 1998. Modulation of macrophage cytokine production by conjugated linoleic acids is influenced by the dietary n-6:n-3 fatty acid ratio. J. Nutr. Biochem. 9:258–266. Watkins, B. A., C. L. Shen, J. P. McMurty, H. Xu, S. D. Bain, K. G. D. Allen, and M. F. Seifert. 1997. Dietary lipids modulate bone prostaglandin E2 production, insulin-like growth factor-I concentration and formation rate in chicks. J. Nutr. 127:1084–1091. Wiegand, B. R. 2000. Conjugated linoleic acid changes performance, compositional and meat quality characteristics. Ph.D. dissertation. Iowa State University, Ames. 14:373–386. Yi-Chia Huang, M. S., L. O. Luedecke, and T. D. Shultz. 1994. Effect of cheddar cheese consumption on plasma conjugated linoleic acid concentrations in men. Nutr. Res. 14:373–386.


Citations

This article has been cited by 19 HighWire-hosted articles: http://jas.fass.org/content/79/7/1821#otherarticles
