Elsevier

Meat Science

Volume 93, Issue 3, March 2013, Pages 517-524
Meat Science

Effect of a high dose of CLA in finishing pig diets on fat deposition and fatty acid composition in intramuscular fat and other fat depots

https://doi.org/10.1016/j.meatsci.2012.10.005Get rights and content

Abstract

Sixteen gilts were fed a control (4% of sunflower oil) or an experimental diet (4% conjugated linoleic acid (CLA) oil). CLA had no effect on intramuscular fat (IMF) content neither in longissimus thoracis (LT) nor in semimembranosus (SM) muscles but increased liver weight, reduced perirenal fat and tended to reduce backfat between the last 3th–4th lumbar vertebrae. Despite the fact that 9c,11t and 10t,12c CLA isomers were included in the same proportion in the diet, the 9c,11t and 9c,11c were the isomers more deposited in all tissues. Addition of CLA in the diet affected fatty acid composition in a tissue specific manner, increasing percentages of SFA in all tissues, reducing percentages of MUFA in LT and LT subcutaneous fat, and of PUFA in LT subcutaneous fat, liver and SM. The FA modification by dietary CLA in LT IMF was reflected in the different lipid fractions, SFA and MUFA mainly in the neutral lipid fraction, and PUFA in the polar fraction.

Highlights

► High level of CLA does not have any effect on performance or intramuscular fat. ► CLA increases the weight of the liver. ► CLA modifies fatty acid composition in a tissue specific manner. ► Neutral and polar lipids were affected differently by CLA supplementation. ► In 100g of loin, CLA deposited would be 53 mg. The predominant isomer is 9c,11t CLA.

Introduction

Fat and fatty acids (FAs), whether in adipose tissue or muscle, contribute importantly to various aspects of meat quality and are central to meat nutritional value (Wood et al., 2008). It is generally assumed that intramuscular fat (IMF) content positively influences sensory quality traits, including flavor, juiciness and tenderness of meat, whereas a low amount of fat results in a less tasty meat. Accordingly, IMF levels should reach values between 2.2 and 3.4% before any noticeable effects on sensory qualities could be detected (Font-i-Furnols, Tous, Esteve-Garcia, & Gispert, 2012).

Selection against fatness or P2 backfat thickness carried out during the last decades in the pig has been very successful (Kempster, Cook, & Grantley-Smith, 1986). Consequently, IMF content has been also dramatically reduced to less than 1% in some lean genotypes widely used nowadays (Wood, 1990). It is believed that IMF develops later and behaves differently from subcutaneous adipose tissue with regard to development of cellularity and metabolic capacity (Lee & Kauffman, 1974). Hence, an increased IMF content without affecting or reducing backfat through a strategic feeding regimen would be a desirable tool in pork meat production. Several nutritional attempts had been studied during the last years; one of them is the inclusion of conjugated linoleic acid (CLA) in foods for growing/finishing pigs for its distributive effect between fat and lean (Dugan, Aalhus, Schaefer & Kramer, 1997).

The CLAs are a mixture of positional and geometric isomers of linoleic acid (9c,12c C18:2), which were first identified in rumen fluid as an intermediate of the biohydrogenation process (Bartlett & Chapman, 1961). In synthetic CLA preparations the 9c,11t and 10t,12c isomers are predominant (often in a 1:1 ratio; Larsen, Toubro, & Astrup, 2003). It appears that the 9c,11t isomer has positive effects on some types of cancer by inhibiting tumorogenesis (Kelley, Hubbard, & Erickson, 2007), while 10t,12c isomer could be responsible for changes in whole-body fat deposition (Pariza, Park, & Cook, 2000). In first studies with pigs dietary CLA increased lean tissue deposition and decreased fat deposition (Dugan et al., 1997, Ostrowska et al., 1999). Comprehensive reviews on the effects of CLA on growth performance and carcass fat deposition in pigs have been published by Azain (2003), Corino, Di Giancamillo, Rossi, and Domeneghini (2005) and López-Bote, Rey, Ortiz, and Menoyo (2004). In general, the response to CLA was not conclusive and inconsistency could be attributed to the type of pig used in studies or to dietary factors like the source of CLA, the dietary fat content or the duration of feeding. According to Azain (2003), it appears that CLA reduces carcass fat in pigs with more than 23 mm subcutaneous fat thickness at 100 kg body weight, but not when fat thickness was less than 20 mm, suggesting that CLA is more effective in fatter genotypes than the average carcass. Moreover, the response to CLA seems to be greater in barrows than in gilts or entire males (Tischendorf, Schone, Kirchheim, & Jahreis, 2002) and in low-energy diets (Dugan, Aalhus, Lien, Schaefer, & Kramer, 2001). Some authors also report an increase in IMF content of CLA fed pigs (Averette Gatlin et al., 2002, Dugan et al., 1999, Jiang et al., 2010, Joo et al., 2002, Morel et al., 2008) which would be very interesting in terms of pork meat quality. However, as for backfat thickness, results are inconsistent because some other studies did not show any affect on IMF content (Corino et al., 2003, Lauridsen et al., 2005, Martin et al., 2008) and the same reasons could be evoked.

In addition, dietary CLA seems to be highly deposited in body tissues of monogastric animals (Bee, 2001, Corino et al., 2005, Jiang et al., 2010, López-Bote et al., 2004) and as a result, in pork and meat products (Schmid, Collomb, Sieber, & Bee, 2006). An increase of saturated fatty acids (SFA) and a reduction of monosaturated fatty acids (MUFA) in subcutaneous tissue and loin were attributed due to an inhibitory effect on the enzyme delta 9 desaturase (Averette Gatlin et al., 2002, Bee et al., 2008).

Due to the inconsistency of the results of CLA on IMF and backfat thickness and since that most of the studies use a dose of 2% of CLA oil in the diet, one of the goals of the present study is to evaluate if the inclusion of a high dose of CLA oil (4%) as the only dietary fat source during fattening of Duroc × Landrace gilts increases IMF content while reducing backfat thickness in order to determine if the lack of consistency between studies is due to the level of CLA inclusion. A further aim is to determine if CLA is equally incorporated and has the same ability to modify FA composition in different tissues of pig. Longissimus thoracis (LT) was chosen as a typical portion consumed fresh, semimembranosus muscle (SM) as representative of ham muscle, LT subcutaneous fat as the main fat deposit where lipid metabolism takes place in the pig and liver as having an important role in the whole body metabolism and due to implications for further human health benefits.

Section snippets

Animals and diets

Sixteen 73 ± 3 kg gilts, progeny of a Landrace sow and a Duroc boar chosen from a larger group were blocked by weight and housed in adjacent individual boxes (2.25 m2) in a room provided with forced ventilation by extraction. Gilts, from 73 ± 3 kg to slaughter at 117 ± 5 kg live weight (LW) (54 days), were randomly assigned within block to one of the dietary treatments. The basal diets were based on barley (536 g/kg from 73 to 91 kg LW or 601 g/kg from 91 to 117 kg LW) and also included manioc (200 g/kg),

Performance, carcass and meat quality parameters

No significant differences in performance parameters of gilts were found due to the replacement of sunflower oil to CLA for a period of 54 days (average daily feed intake: C: 3.16 kg/day, CLA: 3.20 kg/day; average daily weight gain: C: 0.82 kg/day, CLA: 0.82 kg/day; feed to gain ratio: C: 3.84 kg/kg, CLA: 3.94 kg/kg). Animals fed the CLA ration consumed 62.5 g CLA per day on average (a total of 3.37 kg of CLA for whole experiment) had similar final body weight than those fed the control diet (C: 117.9 kg

Discussion

A higher dose of CLA oil (4%) than in previous studies (normally 2%) was used in order to amplify the possible response to CLA in IMF content. Wiegand, Parrish, Swan, Larsen, and Baas (2001) speculated that if body fat was decreased by CLA supplementation then less energy would be required to maintain animal growth, thus making them more efficient. No modification of performance parameters by dietary CLA was observed, which is in agreement with Bee (2001), although Dugan et al. (1997),

Conclusions

The inclusion of a high dose of dietary CLA oil (4%) in gilts of a conventional genotype (Landrace × Duroc) does not increase IMF content. Growth performance was not affected by CLA inclusion but tended to reduce fat deposition, particularly perirenal and increased liver weight. CLA acted in a tissue specific way, increasing SFA in all studied tissues, reducing the MUFA in LT and LT subcutaneous fat, and PUFA in LT subcutaneous fat, liver and SM. The effect of CLA on FA profile was different in

Acknowledgments

The present work has been financed by MICINN (Ministerio de Ciencia e Innovación) in the project AGL2007-65898-C02-02 and Núria Tous is a recipient of an INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria) scholarship. CLA was generously provided by Molimen (Barcelona, Spain).

References (55)

  • N.S. Kelley et al.

    Conjugated linoleic acid isomers and cancer

    The Journal of Nutrition

    (2007)
  • A.J. Kempster et al.

    National estimates of the body composition of British cattle, sheep and pigs with special reference to trends in fatness. A review

    Meat Science

    (1986)
  • T.M. Larsen et al.

    Efficacy and safety of dietary supplements containing CLA for the treatment of obesity

    Journal of Lipid Research

    (2003)
  • C. Lauridsen et al.

    Influence of dietary conjugated linoleic acid (CLA) and age at slaughtering on performance, slaughter- and meat quality, lipoproteins, and tissue deposition of CLA in barrows

    Meat Science

    (2005)
  • D. Martin et al.

    Effect of dietary conjugated linoleic acid in combination with monounsaturated fatty acids on the meat composition and quality traits of dry-cured loin

    Meat Science

    (2008)
  • D. Martin et al.

    Quantitative changes in the fatty acid profile of lipid fractions of fresh loin from pigs as affected by dietary conjugated linoleic acid and monounsaturated fatty acids during refrigerated storage

    Journal of Food Composition and Analysis

    (2009)
  • W. Migdal et al.

    The effect of dietary CLA supplementation on meat and eating quality, and the histochemical profile of the m. longissimus dorsi from stress susceptible fatteners slaughtered at heavier weights

    Meat Science

    (2004)
  • W.R. Morrison et al.

    Preparation of fatty acid methyl esters and dimethylacetals from lipids with boron fluoride–methanol

    Journal of Lipid Research

    (1964)
  • E. Ostrowska et al.

    Dietary conjugated linoleic acids increase lean tissue and decrease fat deposition in growing pigs

    The Journal of Nutrition

    (1999)
  • J. Ruiz et al.

    Improvement of a solid phase extraction method for analysis of lipid fractions in muscle foods

    Analytica Chimica Acta

    (2004)
  • A. Schmid et al.

    Conjugated linoleic acid in meat and meat products: A review

    Meat Science

    (2006)
  • J.D. Wood et al.

    Fat deposition, fatty acid composition and meat quality: A review

    Meat Science

    (2008)
  • Association of Official Analytical Chemist

    Official methods of analysis 18th edition

    (2010)
  • L. Averette Gatlin et al.

    The effects of dietary fat sources, levels, and feeding intervals on pork fatty acid composition

    Journal of Animal Science

    (2002)
  • M.J. Azain

    Conjugated linoleic acid and its effects on animal products and health in single-stomached animals

    The Proceedings of the Nutrition Society

    (2003)
  • J.C. Bartlett et al.

    Detection of hydrogenated fats in butter fat by measurement of cis-trans conjugated unsaturation

    Journal of Agriculture and Food Chemistry

    (1961)
  • G. Bee

    Dietary conjugated linoleic acids affect tissue lipid composition but not de novo lipogenesis in finishing pigs

    Animal Research

    (2001)
  • Cited by (0)

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