Dietary CLA Research Articles

Effect of dietary conjugated linoleic acid on marbling and intramuscular adipocytes in pork1

Dietary CLA has been reported to decrease backfat and increase marbling in pigs. Our objective was to determine whether the increase in marbling involved changes in intramuscular adipocyte number or size or both. Twenty barrows (53 kg) were penned in pairs and pens were randomly assigned to receive diets containing either 1% soybean oil (SBO) or CLA (60% CLA isomers) for 6 wk. Body weight and feed intake were determined weekly. At slaughter, loin samples were obtained and flash frozen for RNA extraction and real-time reverse-transcription PCR analysis of gene expression. After a 24-h chill, loin eye area and backfat depth were measured and subjective marbling and color scores were assigned. Loin, backfat, and belly fat samples were obtained for fatty acid analysis by gas chromatography. Loin samples were also frozen in ice-cold isopentane for histological analysis of intramuscular adipocytes. Dietary CLA did not affect BW or feed intake at any point (P > 0.10), nor did treatment groups differ in HCW (P = 0.417) or loin color (P = 0.500). The CLA-fed pigs did have less (P = 0.018) backfat and smaller (P = 0.047) loin eye area than SBO-fed pigs and had a trend for an increase (P = 0.069) in marbling score. Relative gene expression for markers of preadipocytes (preadipocyte factor 1; Pref-1), differentiating adipocytes (PPARγ), and mature adipocytes [fatty acid binding protein 4 (FABP4) and perilipin (PLIN)] were determined and normalized to the expression of acidic ribosomal phosphoprotein. No significant differences were detected, but the expression of PPARγ (P = 0.265), PLIN (P = 0.265), and FABP4 (P = 0.148) was numerically greater in CLA-fed pigs than in SBO-fed pigs. Loin samples were stained with Oil Red O to identify intramuscular adipocytes. The average cell area was increased (P = 0.030) in CLA-fed pigs. The cis-9,trans-11 and trans-10,cis-12 CLA isomers were incorporated (P = 0.006) into backfat and belly fat, but only trans-10,cis-12 CLA was increased in the loin (P = 0.004) of CLA-fed pigs. The proportion of SFA was increased (P = 0.006) by CLA in all tissues. These results indicate that the increase in marbling in pigs fed CLA may be related to increased intramuscular adipocyte size, and the combination of increased marbling and degree of saturation could improve the eating quality of CLA-fed pork.

Supplementation of Either Conjugated Linoleic Acid or γ-linolenic Acid with or without Carnitine to Pig Diet Affect Flavor of Pork and Neutrophil Phagocytosis

In this study, four different oils containing either CLA, GLA, GLA+Carnitine or corn oil (control) were supplemented to finishing pigs (average 70.8 kg initial BW) diet for 28 d of feeding period. To evaluate the values of the dietary fatty acids, especially in view of sensory and nutritional characteristics of pork; pig performances, carcass characteristics, serum cholesterol, neutrophil phagocytosis, TBARS, electronic nose flavor and fatty acids profile of pork were measured. There were no differences in daily gain and nutrients digestion among treatments, but daily feed intake of CLA enriched diet was lower (P<0.05) than that of other diets. There were no differences in backfat thickness, dressing percentage and carcass grade among pigs fed diets supplemented with different oils. Serum total cholesterol showed a tendency to be lowered in pigs fed GLA enriched diet. TBARS values during storage of pork were higher in belly from pigs fed control diet whereas the values of belly from pigs fed GLA+Carnitine diet were lower than others. However, difference in TBARS was not remarkable in adipose tissue and 4 weeks extended storage regardless of pork parts. Proportion of saturated fatty acids such as C16:0 and C18:0 were higher (P<0.05) in pork loin and thin skirt from pigs fed CLA enriched diet compared to those from other diets. There were no differences in fatty acids profiles of belly and adipose tissue. CLA accumulation in pork was increased by the dietary CLA supplementation and this could be also confirmed by a slight de novo synthesis of CLA in pork from pigs fed CLA free diets. GLA was selectively accumulated to pork adipose tissue and loin from pigs fed GLA enriched diets. There was no accumulation of GLA when GLA was not supplemented, indicating no de novo synthesis of GLA. Phagocytic activity was the highest (p<0.05) in neutrophil of pigs fed GLA+Carnitine supplemented diet, then, followed by pigs fed GLA supplemented diet. There was no difference in phagocytosis between control and CLA treatment although the phagocytosis was numerically lowest in pig fed CLA enriched diet. There were distinct differences in electronic nose flavor pattern among treatments regardless of the parts. This study showed that dietary supplementation of functional fatty acids like CLA or GLA was able to result in characteristic differences in feed intake, TBARS, fatty acids profile and flavor of pork, serum cholesterol regulation and neutrophil phagocytosis. (Key words : CLA, GLA, Carnitine, Pork quality, Fatty acids profile, Flavor, Phagocytosis)

A CLA enriched diet improves organ damage associated with the metabolic syndrome in spontaneous hypertensive rats

The purpose of this study was to provide evidence that dietary CLA can prevent the pathogenesis of metabolic syndrome in tissue structure, suggesting potential benefits in the onset of this syndrome. Wistar male spontaneous hypertensive rats (SHR), were classified into two groups that were fed a standard diet for eight weeks: one with 7.5% sunflower oil (V-SHR group), and the other with 6% sunflower oil and 1.5% CLA (CLA-SHR group). A control healthy group consisted of Kyoto-Wistar male rats fed the standard diet with 7.5% sunflower oil. The animals were sacrificed, and sections of liver, kidneys and aorta were fixed in 10% formaldehyde, and then stained with Hematoxylin and Eosin. Only in the V-SHR group, the stain of the aorta indicated irregular endothelial morphology; liver parenchyma was characterized by an infiltration of inflammatory neutrophils, fibrosis, thickening of the portal vein epithelium, hepatocyte hyperplasia and steatosis. The renal tissue of this group evidenced hyperplasia in the cells of the endothelial of Bowman´s capsule. Abnormal histological changes were not observed in either the control group or the rats fed with CLA, suggesting a protective role of CLA in the onset of metabolic syndrome.

Effects of trans ‐10, cis ‐12 and cis ‐9, trans ‐11 CLA on atherosclerosis in apoE/LDLR −/− mice

The objective of our studies was to verify the potential health-related, anti-atherogenic potency of CLA isomers, fed to apolipoprotein E and LDL receptor double knockout mice (apoE/LDLR−/−), representing a reliable model of atherogenesis. Additionally, the effect of CLA isomers on liver steatosis was observed. In a “long experiment” (LONG), 2-month-old mice with no atherosclerosis were randomly assigned to three experimental groups and fed for the next 4 months. In a “short experiment” (SHORT), 4-month-old mice, with pre-established atherosclerosis, were randomly assigned to three experimental groups and fed for the next 2 months. The experimental diets were: AIN-93G (control), AIN-93G + 0.5% trans-10,cis-12 CLA (t10,c12), and AIN-93G + 0.5% cis9,trans-11 CLA (c9,t11). In both experiments, c9,t11 CLA increased mice body weight. In mice fed t10,c12 CLA weight of liver was threefold (p<0.05) increased what was linked with hepatic steatosis observed in LONG and SHORT experiment. In LONG experiment, t10,c12 CLA significantly (p<0.05) increased plasma TAGs, whereas no such effect was observed in SHORT one. In mice receiving the CLA isomers the level of PPARα and SREBP-1 mRNA in liver were significantly decreased. The expression of their target genes like ACO (PPARα) or FAS (SREBP-1) were not changed. Only c9,t11 increased ACO level in LONG experiment. There were no isomer-specific effects of CLA isomers on the area of atherosclerotic plaque. In conclusion, our results do not support the notion that CLA isomers supplementation to the diet has anti-atherosclerotic effects. CLA isomers have no effect on atherosclerosis in apoE/LDLR−/− mice. Practical applications: CLAs have been shown to occur naturally in food. In the last 10 years, attempts have been made to enrich animal-derived foods in CLA isomers through animal nutrition strategies. Indeed, these attempts resulted in production of functional food such as CLA-enriched milk (butter and cheese), ruminant and non-ruminant meat, as well as eggs. In addition to natural foodstuff, dietary CLA supplements can also contribute to CLA intake in humans. Commercial CLA preparations, fed to laboratory animals, showed several health-related properties, including anti-adipogenic, anti-carcinogenic, anti-atherogenic, and anti-inflammatory effects. The underlying mechanisms of action, however, are only poorly understood. The major objective of our studies was to verify the potential health-related, namely anti-atherogenic potency of CLA isomers, fed to apoE/LDLR−/− mice, representing unique and reliable model of atherogenesis. Additionally, effect of CLA isomers on steatosis was observed.

Dietary conjugated linoleic acid alters long chain polyunsaturated fatty acid metabolism in brain and liver of neonatal pigs

Effects of dietary conjugated linoleic acid (CLA, 1% mixed isomers) on n-6 long-chain polyunsaturated fatty acid (LCPUFA) oxidation and biosynthesis were investigated in liver and brain tissues of neonatal piglets. Fatty acid β-oxidation was measured in tissue homogenates using [1- 14C]linoleic acid (LA) and -arachidonic acid (ARA) substrates, while fatty acid desaturation and elongation were traced using [U- 13C]LA and GC-MS. Dietary CLA had no effect on fatty acid β-oxidation, but significantly decreased n-6 LCPUFA biosynthesis by inhibition of LA elongation and desaturation. Differences were noted between our 13C tracer assessment of desaturation/elongation and simple precursor-product indices computed from fatty acid composition data, indicating that caution should be exercised when employing the later. The inhibitory effects of CLA on elongation/desaturation were more pronounced in pigs fed a low fat diet (3% fat) than a high fat diet (25% fat). Direct elongation of linoleic acid to C20:2n-6 via the alternate elongation pathway might play an important role in n-6 LCPUFA synthesis because more than 40% of the synthetic products of [U- 13C]LA accumulated in [ 13C]20:2n-6. Overall, the data show that dietary CLA shifted the distribution of the synthetic products of [U- 13C]LA between elongation and desaturation in liver and decreased the total synthetic products of [U- 13C]LA in brain by inhibiting LA elongation to C20:2n-6. The impact of CLA on brain LCPUFA metabolism of the developing neonate merits consideration and further investigation.

Individual Isomers of Conjugated Linoleic Acid Reduce Inflammation Associated with Established Collagen-Induced Arthritis in DBA/1 Mice ,

Previously, dietary conjugated linoleic acid [(CLA), an equal mixture of cis-9, trans-11 (c9t11) and trans-10, cis-12 (t10c12) CLA isomers], was found to reduce inflammation in the murine collagen antibody-induced arthritis model, but less so in the murine collagen-induced arthritis (CIA) model, an arthritic model dependent upon acquired immunity. Because CLA is known to alter the acquired immune response, it was hypothesized that feeding CLA after the establishment of arthritis would reduce paw swelling in the CIA model. In this study, upon the establishment of arthritic symptoms, mice were randomized to the following dietary treatments: corn oil (CO) control (n = 6), 0.5% c9t11-CLA (n = 8), 0.5% t10c12-CLA (n = 6), or 1% combined CLA (1:1 c9t11:t10c12-CLA, n = 6). Paws were scored for severity of arthritis and measured for changes in thickness during an 84-d study period. Dietary c9t11- and combined-CLA similarly decreased the arthritic score (29%, P = 0.036, P = 0.049, respectively, when normalized to initial score) and paw thickness (0.11 mm, P = 0.027, P = 0.035, respectively) compared with CO. Dietary t10c12-CLA reduced the arthritic score (41%, P = 0.007 when normalized) and paw thickness (0.12 mm, P = 0.013) relative to CO. Reduced interleukin-1β on d 7 and 21 for all CLA treatments (n = 3) relative to CO suggested that antiinflammatory effects of CLA isomers might work by common mechanisms of known pathways involved in chronic inflammation. In conclusion, dietary CLA reduced inflammation associated with CIA, and both c9t11-CLA and t10c12-CLA exhibited antiinflammatory effects.

Effect of dietary conjugated linoleic acid in combination with monounsaturated fatty acids on the composition and quality traits of cooked loin

Three levels (0%, 1% and 2%) of a conjugated linoleic acid oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low – 19% average and high – 39% average) for pig feeding ( n = 48, eight animals per treatment). The composition and quality traits (fat content, cooking losses, lipid oxidation, fatty acid profile, volatile profile and sensory analysis) of cooked loin, as affected by dietary CLA, MUFA, and CLA × MUFA interaction were studied. CLA and CLA × MUFA did not affect the intramuscular fat content, cooking losses, lipid oxidation, volatile profile and sensory traits of cooked meat. Therefore, CLA could be supplemented to the pig diet without detriment of the measured quality traits of cooked meat, and regardless of the MUFA level of pig diets. Dietary CLA increased the content of SFA and decreased the level of MUFA of meat, and led to a CLA enrichment, regardless the MUFA level of pig diets, but the content of CLA isomers of fresh meat decreased after the cooking process.

Conjugated linoleic acid reduces permeability and fluidity of adipose plasma membranes from obese Zucker rats

AbstractConjugated linoleic acid (CLA) is a dietary fatty acid frequently used as a body fat reducing agent whose effects upon cell membranes and cellular function remain unknown. Obese Zucker rats were fed atherogenic diets containing saturated fats of vegetable or animal origin with or without 1% CLA, as a mixture of cis(c)9,trans(t)11 and t10,c12 isomers. Plasma membrane vesicles obtained from visceral adipose tissue were used to assess the effectiveness of dietary fat and CLA membrane incorporation and its outcome on fluidity and permeability to water and glycerol. A significant decrease in adipose membrane fluidity was correlated with the changes observed in permeability, which seem to be caused by the incorporation of the t10,c12 CLA isomer into membrane phospholipids. These results indicate that CLA supplementation in obese Zucker rats fed saturated and cholesterol rich diets reduces the fluidity and permeability of adipose membranes, therefore not supporting CLA as a body fat reducing agent through membrane fluidification in obese fat consumers.

Conjugated linoleic acid differentially regulates fat deposition in backfat and longissimus muscle of finishing pigs1

This experiment was conducted to investigate the effects of extracellular CLA on proliferation and differentiation of cultured adipocytes and its dietary supplementation on backfat and intramuscular fat deposition in finishing pigs. Seven-day-old Duroc x Landrace x Large White pigs were killed to obtain adipocytes for culture. Adding 3 forms of CLA (cis-9, trans-11 CLA, trans-10, cis-12 CLA, or CLA mixture) at concentrations of 50, 100, 150, 200, 250, 300, 350, and 400 microM to culture medium for 10 d increased cell differentiation (P < 0.05). In addition, 3 forms of CLA enhanced cell proliferation (P < 0.05) at 50 to 350 microM and inhibited cell proliferation (P < 0.05) at a concentration of 400 microM. Seventy-two Duroc x Landrace x Large White crossbred gilts weighing 60.7 +/- 2.8 kg were randomly assigned to 1 of the 3 dietary treatments (control, 1.25% CLA, and 2.5% CLA). The pigs were slaughtered at 100.0 +/- 5.7 kg. Dietary CLA increased lean percentage (3.5 to 4.7%; P = 0.07), intramuscular fat content (P < 0.05), and shear force (P < 0.05), but reduced 10th- and first-rib backfat depth (P <or= 0.05) and lipid oxidation (P < 0.05). The adipocyte diameter in backfat or LM was not affected by CLA. Supplemented CLA reduced Delta(9)-desaturase activity (P < 0.05) in backfat and LM, as well as fatty acid synthetase activity and lipoprotein lipase activity in backfat, but enhanced (P < 0.05) adipocyte fatty acid binding protein mRNA content in LM. These data indicate that dietary CLA regulates fat deposition by affecting adipocyte proliferation, adipocyte differentiation, gene expression, and key metabolic enzymes of lipid metabolism.

Transfer of conjugated linoleic acid from sows to their offspring and its impact on the fatty acid profiles of plasma, muscle, and subcutaneous fat in piglets1

This experiment was conducted to determine if CLA could be transferred from sows to their offspring through the umbilical cord or milk. Eighteen pregnant Dalland sows of mixed parity were used in a completely randomized block design based on parity and BW. The sows were allotted to 1 of 3 groups and fed diets containing 0, 0.5, or 1.0% CLA during the last 50 d of gestation and throughout a 26-d lactation (n = 6). Umbilical cord blood was sampled at parturition. Colostrum and milk were collected from each sow on d 2 and 15 after farrowing. Samples of blood, backfat, and the LM were obtained from piglets at 2 and 26 d of age. Sow reproductive performance and piglet growth were not altered by CLA supplementation during the late gestation and lactation periods. The CLA supplementation of sow diets had an impact on the fatty acid profiles in colostrum and milk. Dietary CLA increased the concentrations of total SFA (linear and quadratic, P < 0.01), but reduced the total MUFA in the colostrum (linear and quadratic, P < 0.01). Although dietary CLA increased the concentrations of total SFA (quadratic, P < 0.01), it had no influence on total MUFA concentrations in the milk. In addition, feeding sows diets supplemented with CLA resulted in increases (linear and quadratic, P < 0.01) in the CLA content of plasma, backfat, and the LM in their offspring. However, trans-10, cis-12-18:2, rather than cis-9, trans-11-18:2, was detected in the umbilical cord blood, which indicates that CLA may be transported from the sow to the fetus in an isomer-specific manner.

Effect of dietary conjugated linoleic acid supplementation in sows on performance and immunoglobulin concentration in piglets1

Conjugated linoleic acid isomers may affect the onset and severity of several diseases, including tumors, atherogenesis, and obesity. They may also modulate the immune response. However, little information regarding the most advantageous duration of CLA supplementation is available. The purpose of this study was to determine whether the length of dietary CLA supplementation of a sow affects growth, immune components, and metabolic and hormonal factors in lactating sows and piglets. Gestating sows were fed a control (0%) and a 0.5% CLA-supplemented diet beginning 7 d before parturition and ending 7 d postpartum (T1), or until weaning (T2; 7 sows per treatment). Colostrum and sow and piglet blood samples were collected for the determination of serum metabolite concentrations and immunoglobulin titer. Piglet BW at weaning were greater (P < 0.05) in the CLA groups compared with the control. Dietary CLA supplementation increased (P < 0.05) serum thyroxine concentration in sows, but serum insulin, glucose, NEFA, IGF-I, and leptin concentrations were not affected by CLA supplementation. Colostral IgG, IgA, and IgM titers were greater in sows fed CLA than in control sows (P < 0.05). At weaning (21 d), serum IgG titer of the piglets was greater (P < 0.05) in the T1 and T2 groups than the control group, but at 13 d postweaning, a difference (P < 0.05) was observed between the control and T2 group. The results from this study indicate potential beneficial effects of 0.5% dietary CLA supplementation from 7 d before parturition until 7 d postpartum in improving BW at weaning and immune components in piglets.

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

Three levels (0%, 1% and 2%) of an enriched CLA oil (28% cis-9, trans-11 and 28% trans-10, cis-12 CLA) were combined with two levels of MUFA (low: 19%; high: 39%) for pig feeding. Changes in the amounts of fatty acids of the neutral lipids (NL), polar lipids (PL) and free fatty acids (FFA) fractions of fresh loin as affected by dietary CLA, MUFA and CLA × MUFA during 7 days of refrigeration were studied. Dietary CLA at 2% and MUFA supplementation caused a decrease in SFA, MUFA, PUFA and CLA isomer contents of NL and PL throughout the storage, whereas the increase in FFA during refrigerated storage was less marked with dietary CLA. Release of CLA isomers of NL and PL was lower than that of non-conjugated PUFA. No significant effect of the interaction CLA × MUFA on the change in the contents of most fatty acids (including CLA isomers) of the lipid fractions was found.

Volatile compounds of fresh and dry-cured loin as affected by dietary conjugated linoleic acid and monounsaturated fatty acids

Three levels (0%, 1% and 2%) of an enriched conjugated linoleic acid oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low (19%) average and high (39%) average) for pig feeding. The profile of volatile compounds of fresh and dry-cured loin as affected by dietary CLA, MUFA and CLA × MUFA interaction was studied by headspace-solid phase microextraction coupled to gas chromatography–mass spectrometry. A total of 27 and 69 compounds were identified in fresh loin and dry-cured loin, respectively. Identified compounds were alcohols, aldehydes, aliphatic hydrocarbons, aromatic hydrocarbons, esters, furans, ketones, nitrogen compounds, sulphur compounds and terpenes. No qualitative differences in volatile compounds caused by the assayed treatments were found neither in fresh loin nor in dry-cured loin. Dietary CLA, MUFA and their interaction did not affect the level of most detected volatiles. Nevertheless, in fresh loin, the level of heptanal significantly increased due to dietary CLA ( p = 0.001) and the area units (AU) for ethyl benzene and 1,3-dimethyl benzene increased at 1% CLA ( p < 0.05). In the case of dry-cured loin, the AU of heptanal, nonanal and 2-nonenal contents increased due to dietary CLA ( p = 0.016, 0.024 and 0.019, respectively).

Dietary conjugated linoleic acid changes belly and bacon quality from pigs fed varied lipid sources1

The objective of this experiment was to determine the effects of dietary lipid source with or without the addition of CLA on bacon composition and quality. Forty-eight barrows at a beginning BW of 55 kg +/- 2.2 were fed 1 of 6 diets for 56 d. These diets consisted of: 1) normal corn (NC), 2) NC + 1.25% CLA-60 oil (NC + CLA), 3) high-oil corn (HOC), 4) HOC + 1.25% CLA-60 oil (HOC-CLA), 5) NC + choice white grease (CWG; NC + CWG), and 6) NC + CWG + 1.25% CLA-60 oil (NC + CWG + CLA). The CLA-60 contains 60% CLA isomers in the oil, and therefore, 1.25% oil was needed to achieve 0.75% CLA in the diet. Soy oil replaced CLA in control diets. Choice white grease and high-oil corn were selected as fat sources for this study because of their utility in energy density for growing-finishing pigs, especially in hot weather. Pigs were slaughtered at an average BW of 113 kg +/- 4.1, and carcasses were fabricated at 24 h postmortem. Statistical analysis was performed using the mixed model procedure of SAS, and the main effects tested were dietary lipid source, CLA, and 2-way interaction. The addition of CLA to each basal diet improved (P < 0.05) belly firmness measured either lean side down or fat side down from the belly bar firmness test [4.39 cm vs. 7.01 cm (lean down) and 5.75 cm vs. 10.54 cm (fat down)] for 0 and 0.75% dietary CLA, respectively. The compression test used on bacon slabs showed that bacon from CLA-supplemented pigs was approximately 20% firmer than that from controls. Pigs fed the HOC diets had softer bellies compared (P < 0.05) with pigs fed the NC diet as measured by the belly bar test [6.94 cm vs. 9.26 cm (fat down)], respectively. Conjugated linoleic acid did not, however, improve bacon sliceability. No differences were observed for moisture, protein, or lipid percentages between any treatments. Overall, there was a CLA effect (P < 0.04) for lipid oxidation, in which the addition of CLA decreased bacon oxidation (0.1498 CLA vs. 0.1638 no CLA). Dietary CLA increased the percentage of SFA in tissues from pigs supplemented with CLA. Dietary inclusion of CLA increased the concentration of all measured isomers of CLA in bacon. Sensory scores of bacon showed no differences for any of the sensory attributes measured between any of the treatments. Our results indicate that inclusion of dietary CLA will improve belly firmness, extend the shelf life stability of bacon, and increase the degree of fat saturation.

Performance and tissue fatty acid profiles in veal calves fed diets supplemented with conjugated linoleic acids

Three groups of six calves each were fed a milk replacer at 0.8 kg and a starter concentrate ad libitum. Calves of the control group received the basal diet supplemented with rapeseed oil at 10 g per kg of feed solids. Calves of treatment groups were fed diets supplemented with a synthetically produced oil containing 62.3% methyl esters of CLA. The CLA-oil was added to milk at expense of rapeseed oil and fed at 5 and 10 g · kg−1 feed solids for 63 days. Calves were slaughtered at 115 days of age. There was no significant effect of CLA on growth, intake of starter, feed conversion, chemical composition of meat and its oxidative stability. Dietary supplementation with CLA at 10 g · kg−1 significantly increased CLA content in m. longissimus dorsi (MLD) from 5.6 to 19.3 mg · 100 g−1, in liver from 13.1 to 68.8 mg · 100 g−1, and in perirenal fat from 0.37 to 3.17 g · 100 g−1. Dietary CLA decreased the ratio of cis-9, trans-11 and trans-10, cis-12 isomers of CLA in tissues, concentration of monounsaturated fatty acids in the MLD and fat, as well as the concentration of fatty acids with 20 and 22 carbon atoms. It can be concluded that in veal calves unprotected CLA apparently escaped ruminal hydrogenation, but was preferentially incorporated into depot fat.

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

Three levels (0%, 1% and 2%) of an enriched conjugated linoleic acid oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low −19% average and high −39% average) for pig feeding. Composition, weight losses, lipid oxidation (thiobarbituric acid test, TBARs), change in the fatty acid content of the lipid fractions and sensory analysis of dry-cured loin as affected by dietary CLA, MUFA and CLA × MUFA interaction were studied. CLA and CLA × MUFA did not affect moisture and intramuscular fat content of dry-cured loin, weight losses during the processing, changes in the content of most fatty acids from lipid fractions and sensory traits. CLA and MUFA supplementation led to lower TBARs values (1.3 mg MDA/kg sample for 0% CLA and 0.9 mg MDA/kg sample for 2% CLA; 1.2 mg MDA/kg sample for low MUFA diets and 0.9 mg MDA/kg sample for high MUFA diets), the highest TBARs values being detected for 0% CLA-low MUFA diets [1.5 mg MDA/kg sample]. The combination of dietary CLA with different MUFA levels in pig diets did not affect most composition and quality traits of dry-cured loin. Dietary CLA and MUFA seemed to lead to lower lipid oxidation in this product.

Oxidative changes of fresh loin from pig, caused by dietary conjugated linoleic acid and monounsaturated fatty acids, during refrigerated storage

Three levels (0%, 1% and 2%) of a conjugated linoleic acid enriched oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (19% and 39% average) for pig feeding. Changes in instrumental colour, lipid oxidation (thiobarbituric acid reactive substances, TBARS) and volatile profile of fresh loin chops, as affected by dietary CLA, MUFA and CLA × MUFA, were studied throughout 7 days of refrigerated storage. Lightness ( L∗) evolution was conditioned by dietary CLA, whereas changes in redness ( a∗) and yellowness ( b∗) were unaffected by dietary supplements. Dietary CLA at 2% led to higher TBARS values of loin chops at day 7 of refrigerated storage ( p < 0.05), while MUFA supplementation and CLA × MUFA interaction did not affect lipid oxidation. Dietary CLA, MUFA or CLA × MUFA did not affect most volatile compounds of loin chops after 7 days of storage.

Meat quality and tissue fatty acid profiles in rabbits fed diets supplemented with conjugated linoleic acid

In this study the deposition of dietary CLA isomers in loin and hindleg meat, liver and fat, and the influence on performance and fatty acid (FA) profile were investigated in growing rabbits. CLA was supplied as synthetically produced oil at 5 and 10 g/kg diet for the whole fattening period (six weeks) or three weeks before the slaughter. CLA had no or limited effect on feed intake, growth, carcass traits and composition of meat. Treatment with CLA increased the proportion of saturated FA at the expense of monounsaturated FA in meat and liver. Supplementation of the diet with CLA increased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) CLA in lipids of meat from &lt; 1 mg/g FA up to 36 mg/g FA. Adipose and hepatic tissue incorporated the highest (44 mg/g FA) and the lowest (14 mg/g FA) amount of CLA, respectively. The concentration of CLA in tissue lipids increased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) with increasing CLA content in the diet. Duration of CLA feeding had no effect on CLA deposition. Thus, dietary inclusion of CLA at higher concentration (10 g/kg) and feeding CLA-supplemented diet for a shorter period seems to be more suitable for production of CLA-containing rabbit meat. The ratio of the two most abundant isomers of CLA,&lt;I&gt; cis&lt;/I&gt;-9, &lt;I&gt;trans&lt;/I&gt;-11 and &lt;I&gt;trans&lt;/I&gt;-10, &lt;I&gt;cis&lt;/I&gt;-12 in tissues differed from that in the CLA-enriched diet. In all tissues the relative proportion of the former isomer was lower than in the diet. The experiment demonstrated that feeding synthetic CLA to rabbits is a means of enriching rabbit meat with CLA, which could provide a healthier product for human consumption.

Influence of dietary CLA isomers and selenium compounds on the fatty acid and amino acid profiles in blood plasma of rats

Influence of dietary CLA isomers and selenium compounds on the fatty acid and amino acid profiles in blood plasma of rats

Dietary Conjugated Linoleic Acid to Control the Population of Wild Bird Species Considered a Pest

Many bird species conflict with human economic, aesthetic, or vital interests (Wetherbee et al. 1964). Pigeons (Columbia livia) cause tremendous damage and pollution to park benches, statues, vehicles, buildings, and domestic water supplies due to the highly corrosive uric acid contained in their droppings. Previous attempts to manage bird populations have failed because of high cost, variable success, and difficulty in application. A previous study demonstrated that certain dietary fatty acids can cause embryonic mortality in fertile eggs (Donaldson and Fites 1970). This suggests a potential approach for controlling wild bird populations. Cook et al. (1996) reported that dietary conjugated linoleic acid (CLA; a mixture of positional and geometrical isomers of linoleic acid) contributed to the control of bird populations at airports, cattle feed lots, and parks. Foods derived from ruminant animals contain the highest natural concentrations of CLA (Chin et al. 1992). Scientists have attributed multiple beneficial properties to CLA, such as anticarcinogenic (Ha et al. 1990), anti-atherogenic (Nicolosi et al. 1997), fat-reducing effects (Park et al. 1997), and immune-enhancing activity in chickens (Cook et al. 1993). A previous study showed that a low-fat diet supplemented with 0.5% CLA caused 100% embryonic mortality in the fertile chicken eggs (Aydin et al. 2001). Another study showed that a diet containing 3%, 2%, or 1% CLA caused 100% embryonic mortality in fertile Japanese quail (Coturnix coturnix japonica) eggs after 6 days, 10 days, or 12 days of feeding, respectively (Aydin and Cook 2004). Researchers suggested that dietary CLA caused significantly higher embryonic mortality in fertile eggs by changing fatty acid composition of egg yolk (Lee 1996, Aydin et al. 2001). On-site management actions such as barriers, scare tactics, chemical repellents, and habitat modifications to control pigeon populations often correlate with high cost, variable success, and difficulty in application (Smith et al. 1999). We investigated the effect of dietary CLA on hatchability of fertile pigeon eggs to determine the potential for using CLA to control the population of wild bird species that are considered pests. Use of CLA could provide managers with a more cost-effective means of controlling pigeon populations. Study Area