Conjugated Linoleic Acid Oil Research Articles

Effect of dietary conjugated linoleic acid levels on growth performance, muscle fatty acid profile, hepatic intermediary metabolism and antioxidant responses in genetically improved farmed Tilapia strain of Nile tilapia Oreochromis niloticus

An 8-week feeding trial was conducted to determine the effect of dietary conjugated linoleic acid (CLA) on growth performance, muscle fatty acid profile, hepatic intermediary metabolism and antioxidant responses in genetically improved farmed Tilapia (GIFT) strain of Oreochromis niloticus (initial body weight: 42.6 ± 0.4 g, mean ± standard deviation). Three replicated groups of GIFT strain of Nile tilapia were hand-fed to satiation, twice a day, with the diets in which CLA oil, containing mainly the bioactive cis-9, trans-11 and trans-10, cis-12 isomers, was included at 0 (control), 0.5%, 1%, 1.5%, 2% and 2.5%, respectively, at the expense of fish oil to maintain the constant lipid and energy levels. Growth performance and feed utilization showed no significant differences among the treatments (P > 0.05). The dietary inclusion of CLA modified total percentages of the main groups of fatty acids. Increasing saturated fatty acid content and reduced mono-unsaturated fatty acid contents in muscle were observed with increasing dietary CLA inclusion (P < 0.05). Total n-3 fatty acids and total polyunsaturated fatty acids tended to decline with increasing dietary CLA levels (P < 0.05), but n-6 fatty acids showed no significant differences among the treatments (P > 0.05). Dietary CLA supplementation resulted in the significant increase in the trans-10, cis-12 and cis-9, trans-11 CLA isomers in muscle (P < 0.05) and also significantly influenced several hepatic enzymatic activities, such as succinate dehydrogenase, lactate dehydrogenase, malic dehydrogenase, lipoprotein lipase and hepatic lipase activities (P < 0.05). Reduced superoxide dismutase and glutathione peroxidase activities, and the decline in malondialdehyde levels were observed in fish fed the CLA-supplemented diets (P < 0.05), indicating that dietary CLA supplementation showed a powerful antioxidant effect for this fish species. Our study was the first report involved in the effect of dietary CLA inclusion on hepatic intermediary metabolism and antioxidant responses in fish, which could be used as indicators of nutritional and physiological status of the fish species.

Dietary combination effects of conjugated linoleic acid and flaxseed or fish oil on the concentration of linoleic and arachidonic acid in poultry meat

This study was conducted to determine the effects of the combination of dietary conjugated linoleic acid (CLA) and n-3 fatty acids on the linoleic acid (C18:2n-6) and arachidonic acid (C20:4n-6) concentrations of broiler chicken breast and thigh muscles. One hundred and twenty broilers were raised to 6 wk of age. All chicks were fed a basal corn-soybean meal diet containing 5 different fat sources at an inclusion level of 2% total fat: 1) CLA, 2) flaxseed oil, 3) menhaden fish oil, 4) CLA and flaxseed oil, and 5) CLA and menhaden fish oil. Eight broilers from each treatment were processed at 4 and 6 wk of age. Breast and thigh muscle samples were collected and analyzed for total fat content and fatty acid composition. The results showed that broilers from the CLA and fish oil treatment had lower arachidonic acid concentrations in both breast and thigh muscles than those fed the flaxseed oil diet or the CLA and flaxseed oil diet (P < 0.05). The arachidonic acid concentration and n-6:n-3 ratio of breast and thigh samples from the menhaden fish oil diet were similar to those of the CLA and fish oil diet (P > 0.05), but the inclusion of linoleic acid into chicken thigh muscles of broilers fed the CLA and menhaden fish oil diet improved significantly when compared with that of the diet containing menhaden fish oil only. Thus, the combination of CLA and menhaden fish oil is recommended to reduce the concentrations of linoleic and arachidonic acids in broiler chicken breast and thigh muscles.

Dietary conjugated linoleic acid (CLA) for finishing Nile tilapia

A 8-week feeding trial was conducted to evaluate the nutritional value of dietary conjugated linoleic acid (CLA) for finishing Nile tilapia evaluating its effects on growth performance, whole body and filet compositions, fatty acid composition, plasma lipid parameters, filet texture, liquid loss and holding capacity. Triplicate groups of Nile tilapia were hand-fed until apparent satiation on diets in which CLA oil was supplemented at 0 (control), 5 or 10 g kg−1. No differences were observed on weight gain, feed intake, feed/gain ratio, protein efficiency ratio, hepatosomatic index, visceral fat, filet yield and survival between treatments. Fish-fed CLA diets had increased whole body crude protein and reduced filet lipid content. The total plasma cholesterol and triacylglycerol decreased with CLA supplementation. Neither 5 nor 10 g kg−1 dietary CLA improved liquid-holding capacity and filet texture when compared with fish fed the control diet. Fish-fed dietary CLA showed lower whole body and filet C18:3(n-6), C18:3(n-3) and C20:2(n-6) levels and higher levels of C18:0. CLA deposition in filet and whole body (16 mg–235 mg g−1 of tissue) are higher than presented in natural sources of CLA, proving to be a great product to increase CLA consumption by humans.

Effect of dietary conjugated linoleic acid (CLA) on growth performance, body composition and hepatic intermediary metabolism in juvenile yellow catfish Pelteobagrus fulvidraco

The present study was conducted to determine the effect of dietary conjugated linoleic acid (CLA) on growth performance, body composition and hepatic intermediary metabolism in juvenile yellow catfish Pelteobagrus fulvidraco (initial body weight: 1.87 ± 0.04 g, mean ± SD). The five isonitrogenous (35% crude protein) experimental diets were formulated to contain graded CLA levels of 0 (control), 0.5, 1, 1.5 and 2%, respectively. Three replicated groups of fish were fed to satiation, twice a day, over a period of 8 weeks with CLA oil, containing mainly the bioactive cis-9, trans-11 and trans-10, and cis-12 isomers. The increase of dietary CLA levels reduced growth performance, feed conversion rate (FCR), condition factor, hepatosomatic index and viscerosomatic index of yellow catfish. Increasing dietary CLA levels significantly reduced lipid contents in the whole body and liver. The dietary inclusion of CLA modified total percentages of the main groups of fatty acids. Increasing saturated fatty acid (SFA) content and reduced mono-unsaturated fatty acid (MUFA) contents in the whole body were observed with increasing dietary CLA inclusion. A gradual reduction of 16:1 and 18:1 fatty acids was depicted in the whole body with increasing CLA levels. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) profiles showed no significant differences among the treatments. Total polyunsaturated fatty acids (PUFA) tended to increase with increasing dietary CLA levels. Dietary CLA supplementation resulted in a significant increase of the trans-10, cis-12 and cis-9, and trans-11 CLA isomers in the whole body, and also significantly influenced several hepatic enzymatic activities, such as succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), malic dehydrogenase (MDH), lipoprotein lipase (LPL) and hepatic lipase (HL) activities. These indicate that despite promoting the CLA and PUFA deposition in the whole body, dietary CLA supplementation should be carefully evaluated in intensive yellow catfish farming as it reduces growth performance and feed utilization.

Dietary CLA alters intramuscular fat and fatty acid composition of pig skeletal muscle and subcutaneous adipose tissue

The present study was conducted to determinate the responsiveness of different levels of dietary conjugated linoleic acid (CLA) on intramuscular fat (IMF) and fatty acid composition of skeletal muscle and fat in pigs fed from 59.5 to 133.5kg. Forty female Large Whitex(Large WhitexLandrace) pigs were used. Four levels (0%, 0.5%, 1% and 2%) of a commercial enriched CLA oil supplementation (60% of CLA isomers, 30% cis-9, trans-11 and 30% trans-10, cis-12) were fed to pigs. Carcass, ham, foreleg and loin weights were recorded. Dietary CLA enrichment increased the loin weight (P<0.01) and the combined weights of hams+forelegs+loins (P<0.02). IMF content in Longissimus dorsi was also increased by dietary CLA treatment (P<0.001) and a linear response was observed. Dietary CLA increased saturated fatty acids (SFA) and decreased monounsaturated fatty acids (MUFA) in muscle and adipose tissue (P<0.001). Feeding 1% CLA to finishing swine increases IMF in heavy pigs slaughtered at an average weight of 133.5kg.

Dietary Conjugated Linoleic Acid Induces Tissue-Specific Lipoprotein Lipase mRNA Modulation in High-Sucrose-Fed Mice

Background/Aims: To delineate the hypotriglyceridemic effect of conjugated linoleic acid (CLA) in mice, the effect of this fatty acid on lipoprotein lipase (LPL) and apolipoprotein C-III (ApoCIII) mRNA accumulation in muscle, adipose and liver tissue was studied. Methods: CD-1 mice were housed in groups of 6 and randomized to one of three experimental diets for 3 weeks: SUC: 65% sucrose by weight; CLA: 1% CLA oil (34.4% c9,t11; 35.1% t10,c12 and 4.1% other conjugated isomers) and 65% sucrose, and DEX: 65% dextrose, as a control. Results: LPL mRNA levels in muscle tissue were increased in the DEX group and in the CLA group (240% increase) compared with the SUC group. In contrast, LPL mRNA levels were 81% lower in epididymal adipose tissue from the CLA group compared with the SUC group. There was no effect of dietary treatments on ApoCIII mRNA accumulation in the liver. Conclusions: These data suggest that dietary CLA may induce partitioning of circulating triglycerides to muscle tissue, preventing their accumulation in adipocytes.

A Diet Rich in Conjugated Linoleic Acid and Butter Increases Lipid Peroxidation but Does Not Affect Atherosclerotic, Inflammatory, or Diabetic Risk Markers in Healthy Young Men

Intake of conjugated linoleic acid (CLA) has been demonstrated to beneficially affect risk markers of atherosclerosis and diabetes in rats. CLA is naturally found in milk fat, especially from cows fed a diet high in oleic acid, and increased CLA intake can occur concomitantly with increased milk fat intake. Our objective was to investigate the effect of CLA as part of a diet rich in butter as a source of milk fat on risk markers of atherosclerosis, inflammation, diabetes type II, and lipid peroxidation. A total of 38 healthy young men were given a diet with 115 g/d of CLA-rich fat (5.5 g/d CLA oil, a mixture of 39.4% cis9, trans11 and 38.5% trans10, cis12) or of control fat with a low content of CLA in a 5-wk double-blind, randomized, parallel intervention study. We collected blood and urine before and after the intervention. The fatty acid composition of plasma triacylglycerol, cholesterol esters, and phospholipids reflected that of the intervention diets. The CLA diet resulted in increased lipid peroxidation measured as an 83% higher 8-iso-prostaglandin F2α concentration compared with the control, P < 0.0001. We observed no other significant differences in the effect of the interventions diets. In conclusion, when given as part of a diet rich in butter, a mixture of CLA isomers increased lipid peroxidation but did not affect risk markers of cardiovascular disease, inflammation, or fasting insulin and glucose concentrations.

Changes in the Fatty Acid Profile of the Subcutaneous Fat of Swine throughout Fattening As Affected by Dietary Conjugated Linoleic Acid and Monounsaturated Fatty Acids

The fatty acid profile of the subcutaneous fat of pigs and its evolution throughout fattening as affected by dietary conjugated linoleic acid (CLA), monounsaturated fatty acids (MUFA), and their interaction (CLAxMUFA) were studied. 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% average; and high, 39% average) for pig feeding (288 gilts). Subcutaneous shot-biopsies were taken from 48 animals at the beginning of the trial (S1, 70 kg), 14 days later (S2, 80 kg), and at slaughter (S3, 107 kg). Inclusion of CLA in the diet caused an increase during fattening in cis-9, trans-11 CLA, trans-10, cis-12 CLA, and saturated fatty acids (SFA) contents of pig backfat and a decrease in MUFA and polyunsaturated fatty acids (PUFA). MUFA supplementation also led to a MUFA enrichment of backfat. The interaction CLAxMUFA affected the SFA content. The rates of accumulation of CLA isomers, SFA, and MUFA throughout the trial did not follow a linear behavior, such rates being higher from S1 to S2 than from S2 to S3. These rates were also influenced by dietary CLA and MUFA levels. The increase in the ratio of saturated to unsaturated fatty acids of backfat caused by dietary CLA might be balanced by supplementation of pig diets with MUFA.

Hot Topic: Fatty Acid and Conjugated Linoleic Acid (CLA) Isomer Composition of Commercial CLA-Fortified Dairy Products: Evaluation After Processing and Storage

Conjugated linoleic acid (CLA) exerts a strong positive influence on human health but intake of these fatty acids is typically too low, and increased consumption of CLA is recommended. A good way to raise the CLA content in the diet without a radical change in eating habits seems to be the enrichment of commonly consumed food products with CLA supplements. This study analyzed the total fatty acid content and the CLA isomer composition of 6 commercially available CLA-fortified dairy products during processing and 10 wk of refrigerated storage. Research was carried out by combining gas chromatography and silver-ion HPLC. The tested samples were a CLA oil supplement, and several skim milk dairy products fortified with the supplement (milk, milk powder, fermented milk, yogurt, fresh cheese, and milk-juice blend). The CLA oil supplement was added such that the consumer received 2.4 g/d of CLA by consuming 2 servings. The predominant isomers present, C18:2 cis-9, trans-11 CLA and C18:2 cis-10, trans-12 CLA, were in at a similar ratio, which ranged from 0.97 to 1.05. These major isomers were not significantly affected by processing but a decrease in total CLA in fresh cheese samples was detected after 10 wk of refrigerated storage. Refrigerated storage and thermal treatment resulted in significant decreases or disappearance of some of the minor CLA isomers and a significant increase of trans, trans isomers from both cis, trans, trans, cis, and cis, cis isomers especially in CLA-fortified milk powder but also in fermented milk, yogurt, and milk-juice blend.

Phase 2 enzyme induction by conjugated linoleic acid improves lupus-associated oxidative stress

Conjugated linoleic acid (CLA) exhibits anticancer and anti-inflammatory properties. Its ability to increase total GSH (GSH+GSSG) amount and gamma-glutamylcysteine ligase (γGCL) protein expression was recently associated with the inhibition of typical pathological signs in MRL/MpJ-Fas lpr mice (MRL/ lpr). In the present study the ability of CLA to modulate oxidative stress and phase 2 enzyme activity in the same animal model was investigated. Disease severity was associated with age-dependent production of anti-double-stranded DNA antibodies (anti-dsDNA IgGs) and with enhanced extent of oxidative stress markers: reduced total GSH, increased protein 3-nitrotyrosines (3-NT), and protein-bound carbonyl (PC) amounts. To examine the effect of CLA on antioxidant status, CLA or olive oil (as control) was administered to pregnant MRL/ lpr mice. Significantly higher total GSH and Trolox equivalent antioxidant capacity (TEAC) levels were measured in serum of CLA-treated dams (and their pups), as compared with controls. Finally, the antioxidant and chemopreventive properties of CLA were investigated in old MRL/ lpr mice. Sera of CLA-treated mice contained higher concentrations of total GSH which were negatively correlated with the levels of oxidative stress markers. Moreover, increased GSH, γGCL, glutathione S-transferase (GSTs), and NAD(P)H:quinone oxidoreductase (NQO1) activities were measured in liver and spleen of CLA-treated animals. In conclusion our data indicate that the activation of detoxifying enzymes may be one of the mechanisms whereby dietary CLA down-regulates oxidative stress in MRL/ lpr mice.

Effect of conjugated linoleic acid on the growth of weaned piglets

The effect of conjugated linoleic acid (CLA) on growth parameters of sixteen piglets, divided into two groups was studied. The experiment started when the piglets were 29 days old. Prior the age of 39 days animals were fed restrictively on the same amount of feed, independent of the weight of animal. During the next period of the experiment, between ages of 40 and 75 days, the animals were fed individually, with 1.8 times of maintenance energy. Animals were weighed every week. The experimental group was fed extra with supplement of 1.5% of 80% CLA. The same amount of sunflower oil was used in the control group. During the last period of the experiment, between ages of 76 and 123 days, animals were fed ad libitum with feed without any CLA or sunflower supplement. CLA decreased average feed consumption and weight of the animals. All observed differences were found in the third or last period of the experiment, after the administration of CLA or sunflower oil was finished.

Enrichment of channel catfish ( Ictalurus punctatus) fillets with conjugated linoleic acid and omega-3 fatty acids by dietary manipulation

An experiment was conducted in aquaria with channel catfish ( Ictalurus punctatus) to determine the efficacy of augmenting fillets with conjugated linoleic acid (CLA) and omega-3 highly unsaturated fatty acids ( n − 3 HUFA) by feeding diets amended with products containing high levels of these nutrients. Refined menhaden fish oil at 1.5% of diet supplied the n − 3 HUFA. CLA was used at dietary levels of 0.5% and 1% with a preparation that contained approximately 65% isomers of CLA. Corn oil was added to the basal diet at maximum inclusion level for added lipids of 3% for the control diet and to adjust total added lipid content of the other diets to 3%. Average initial body weight was 57.39 ± 0.25 g/fish. Six experimental diets were fed twice daily to four replicate aquaria for six weeks. At that time, fish were group weighed for determination of weight gain and feed conversion. Fillets of six fish per aquarium were recovered and stored at − 80 °C for moisture and total lipid analyses, fatty acid analysis, and sensory evaluation. Results showed feed consumption and feed conversion did not differ ( P > 0.05). Significantly ( P < 0.05) greater body weight gains were observed only for fish fed the diets with two combinations of CLA and 1.5% fish oil compared to fish fed the diet containing 0.5% CLA and corn oil. Fillet n − 3 HUFA levels were significantly ( P < 0.05) elevated for fish fed diets containing fish oil when compared to n − 3 HUFA of fillets of fish fed diets containing either corn oil or CLA and corn oil. Similarly, fillets from fish fed diets amended with CLA contained substantial amounts of CLA of up to 6.4% of total lipids. Fillets from fish fed corn oil or fish oil diets had no CLA. Taste panel evaluation indicated that fillets containing n − 3 HUFA and CLA were essentially without fishy off-flavor and had excellent sensory qualities. Catfish fillets produced by amending diets with sources of n − 3 HUFA and CLA at the levels used in this study would contain elevated levels of these nutraceuticals and could be an important human food source for these healthful fatty acids.

CLA and n-3 PUFA differentially modulate clinical activity and colonic PPAR-responsive gene expression in a pig model of experimental IBD

Conjugated linoleic acid (CLA) and n-3 polyunsaturated fatty acids (PUFA) have been proposed as important pharmaco-nutrients for modulating mucosal immunity and therapeutic responses in patients with inflammatory bowel disease (IBD). We evaluated the ability of CLA and n-3 PUFA alone or in combination to modulate IBD in a pig model of dextran sodium sulfate (DSS)-induced colitis. Sixty-four, 15-day-old pigs were used to evaluate the effect of CLA, n-3 PUFA and a 50:50 mixture of CLA and n-3 PUFA on growth, clinical activity and colonic PPAR-responsive gene expression. Diets were formulated to contain: 1.33% soybean oil (control); 1.33% CLA; 1.33% fish oil; or 1.33% of a 50:50 mixture of CLA and fish oil. Intestinal inflammation was induced by an intragastric challenge with DSS on day 42 of dietary supplementation. The colonic expression of peroxisome proliferator-activated receptor-gamma (PPAR-gamma), PPAR gamma- and delta-responsive genes, keratinocyte growth factor (KGF) and tumor necrosis factor (TNF-alpha) were assayed by quantitative RT-PCR. The onset of IBD was delayed, colitis less severe and growth suppression attenuated in pigs fed CLA, which correlated with induction of colonic PPAR gamma and its responsive gene PPAR gamma-coactivator-1alpha (PGC1-alpha) and downregulation of TNF-alpha. However, dietary supplementation with n-3 PUFA alone or in combination with CLA resulted in an early onset of disease (i.e., day 2) and faster recovery on days 6 and 7, which correlated with a marked induction of the PPAR delta-responsive gene uncoupling protein 3 (UCP3). CLA and n-3 PUFA acted synergistically to upregulate colonic KGF expression in DSS-challenged pigs but n-3 PUFA blocked CLA-induced PPAR gamma activation. Dietary CLA-supplementation upregulated colonic PPAR gamma expression and contributed to delaying the onset of experimental IBD, whereas n-3 PUFA failed to protect from IBD, although it accelerated colonic regeneration and clinical remission by activating PPAR delta.

Effects of conjugated linoleic acid on linoleic and linolenic acid metabolism in man

Evidence from animal studies suggests that conjugated linoleic acid (CLA) modulates plasma and tissue appearance of newly synthesized PUFA. The effects of a 1.2g (0.5 % energy) daily intake of the cis-9,trans-11 (c9,t11) isomer of CLA, trans-10,cis-12 (t10,c12) isomer of CLA or olive oil (placebo) on linoleic acid (LA) and linolenic acid (LNA) metabolism in healthy human volunteers was investigated. Fifteen subjects were fed an experimental diet and supplemented with c9,t11-CLA, t10,c12-CLA or placebo for 7 d before consuming a tracer dose of U-[(13)C]LA (50 mg) and U-[(13)C]LNA (50 mg). Blood samples were taken at 0, 2, 4, 6, 8, 24, 48, 72 and 168 h and analysed using high-precision MS. No differences between the groups in peak plasma [(13)C]LA (10.3-11.6 % of dose), [(13)C]LNA (2.5-2.9 % of dose), [(13)C]arachidonic acid (0.09-0.12 % of dose), [(13)C]EPA (0.04-0.06 % of dose) or [(13)C]DHA (0.06-0.10 % of dose) were detected. Concentration v. time curves (area under the curve) also showed no significant differences between groups. This suggests that, in healthy human subjects consuming a diet with adequate intake of essential fatty acids, CLA does not affect metabolism of LA or LNA.

Conjugated linoleic acid increased C-reactive protein in human subjects

We previously showed that conjugated linoleic acid (CLA) increases 15-keto-dihydro-prostaglandin F2alpha, a marker for cyclooxygenase-mediated lipid peroxidation and thus an indicator of cyclooxygenase-mediated inflammation. The aim of the present study was to investigate the effects of CLA on other indicators of inflammation in human subjects, including C-reactive protein, TNF-alpha, TNF-alpha receptors 1 and 2, and vascular cell adhesion molecule-1. In a double-blind, placebo-controlled study, fifty-three human subjects were supplemented with a mixture (4.2 g/d) of the isomers cis-9,trans-11 CLA and trans-10,cis-12 CLA or control oil for 3 months. CLA supplementation increased levels of C-reactive protein (P=0.003) compared with the control group. However, no changes in TNF-alpha, TNF-alpha receptors 1 and 2, and vascular cell adhesion molecule-1 were detected.

Effect of linseed oil supplementation on concentrations of (n‐3) polyunsaturated fatty acids in liver phospholipids of rats fed diets containing either an oil rich in conjugated linoleic acids, sunflower oil or high‐oleic acid sunflower oil

This study investigated the metabolism of alpha-linolenic acid and the formation of eicosanoids in rats fed diets with three different dietary fats (30 g/kg diet): either a conjugated linoleic acid (CLA) preparation with a high concentration of cis-9, trans-11 CLA (32.2 g/100 g) and trans-10, cis-12 CLA (33.3 g/100 g) and a low concentration of linoleic acid (0.5 g/100 g), sunflower oil (SFO) with a high concentration of linoleic acid or high-oleic acid sunflower oil (HO-SFO) with a high concentration of oleic acid. Basal diets with those oils were fed for 4 weeks. In the fifth week, the same diets supplemented with 50 g of linseed oil/kg as a source of alpha-linolenic acid were fed. To study the effect of the oils on the metabolism of alpha-linolenic acid, the amounts of individual (n-3) polyunsaturated fatty acids (PUFA) in liver phospholipids (phosphatidyl choline and phosphatidyl ethanolamine) were determined; to study the effect on eicosanoid formation, the concentrations of various two-series eicosanoids in liver and plasma, the activity of the secretory phospholipase A2 and the relative mRNA concentrations of cyclooxygenases-1 and 2 in the liver were measured. Rats fed the CLA diets had the highest concentrations of long chain (n-3) PUFA deriving from delta6, delta5 and 14-desaturation of alpha-linolenic acid in liver phospholipids; rats fed the SFO diet had the lowest concentrations of those fatty acids. The concentration of arachidonic acid in liver phospholipids and the concentrations of eicosanoids in liver and plasma were lowest in rats fed the CLA diet and highest in the rats fed the SFO diet. Moreover, rats fed the CLA diet had a higher gene expression of delta6-desaturase in the liver than the other two groups of rats. The results show that feeding the CLA oil reduced the formation of arachidonic acid and eicosanoids but enhanced the formation of long chain (n-3) PUFA and their incorporation into tissue lipids when compared with feeding SFO or HO-SFO.

Effects of dietary conjugated linoleic acid and fish oil supplementation on performance and egg quality in laying hens

1. Laying hen performance, yolk fat fatty acid concentrations and firmness of eggs were evaluated with respect to the inclusion in the diet of conjugated linoleic acid (CLA) and fish oil. 2. Nine diets were arranged factorially, with three levels of supplementation of CLA (1, 3 and 5 g/kg) and fish oil (0, 14 and 20 g/kg). 3. Type of diet did not affect egg production traits. 4. CLA addition increased yolk weight and yolk fat concentrations of CLA, saturated and total long-chain n-3 fatty acids, but decreased those of monounsaturated and total long-chain n-6 fatty acids. 5. Fish oil addition increased long-chain n-3 fatty acids yolk fat concentrations but decreased those of CLA, saturated and long-chain n-6 fatty acids. 6. Effects of CLA addition on yolk fat concentrations of C22:4 n-6 and C20:5 n-3 were greater when no fish oil was added to the diet. 7. CLA supplementation increased linearly yolk moisture and firmness and altered albumen and yolk pH.

Effects of conjugated linoleic acid levels and feeding intervals on performance, carcass traits and fatty acid composition of finishing barrows

Two experiments were conducted to investigate the effects of dietary conjugated linoleic acid (CLA) on performance, carcass traits, fatty acid composition and subcutaneous adipose tissue cellularity in finishing barrows. In Experiment 1, 54 crossbred barrows were allotted to one of three treatments, with six pens per treatment and three barrows in each pen. The pigs were fed a diet containing 0, 2, or 4% CLA oil for 6 weeks. Daily gain (P < 0.01) and feed efficiency (P < 0.01) improved with dietary CLA. Loin muscle area (P = 0.01) and intramuscular fat (P = 0.01) increased while 10th rib fat (P = 0.03) and last rib fat (P = 0.02) thickness decreased with increasing dietary CLA. Total CLA isomers increased (P < 0.01) with increasing dietary CLA. Myristic, palmitic and stearic acid levels were increased while oleic, linoleic, linolenic and arachidonic acid decreased in loin muscle and subcutaneous adipose tissue. In Experiment 2, barrows (n = 54) were allotted to one of two treatments with nine pens per treatment and three pigs in each pen. Pigs were fed a diet supplemented with 4% CLA for 3 or 6 weeks before slaughter. Over the entire experimental period, daily gain and feed efficiency were higher (P < 0.01) when CLA was fed for a longer period. Loin muscle area (P < 0.01) and intramuscular fat (P < 0.01) increased while backfat thickness at the 10th (P = 0.03) and last rib (P = 0.04) decreased when CLA was fed for 6 vs. 3 weeks. The number of cells in subcutaneous adipose tissue was not affected while adipocyte volume decreased (P = 0.01) with longer feeding time on dietary CLA. The increased CLA content of pork from CLA fed pigs provides the pork industry with an opportunity to provide value-added, healthful meat products for human consumption with respect to CLA intake and potential improvements in human health.

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on fatty acid composition of adipose tissues in beef cattle.

Thirty-six Angus x Hereford heifers (365 +/- 60 kg) were used to determine the effects of supplemental dietary lipid sources on fatty acid composition of i.m., perianal (p.a.), and s.c. lipid depots. Lipid was supplied to diets as either corn oil or a rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed. Following an initial 56-d feeding period, heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% rumen-protected CLA salt (RPCLA) containing 31% CLA. The trans-10, cis-12 CLA concentration was greatest (P < 0.05) for heifers fed RPCLA and OIL diets and least (P < 0.05) for CON, regardless of time on dietary treatment. Heifers fed supplemental RPCLA had greater (P < 0.05) total CLA content than either CON- or OIL-fed heifers. Adipose tissue concentration of trans-11 vaccenic acid (TVA) was less (P < 0.05) for CON than OIL or RPCLA, which did not differ (P > 0.05). Percentages of C18:1 trans-10 were least (P < 0.05) in i.m. lipid compared with p.a. and s.c., which did not differ (P > 0.05). Following 60 d of lipid supplementation, heifers fed OIL and RPCLA had lower (P < 0.05) concentrations of oleic acid and total monounsaturated fatty acids (MUFA) compared with CON. The ratio of cis-9, trans-11 CLA:TVA was higher (P < 0.05) for heifers fed 60 vs. 32 d, but did not differ (P > 0.05) between adipose depots. Feeding OIL increased (P < 0.05) adipose concentration of C18:2 fatty acid, whereas feeding RPCLA increased (P < 0.05) total CLA isomers by 22%. Intramuscular lipid contained the lowest (P < 0.05) percentage of cis-9, trans-11 CLA, total CLA, C18:1 cis-9, C18:1 trans-10, and TVA. Total CLA and cis-9, trans-11 CLA isomers were increased (P < 0.05) in p.a. and s.c. adipose depots, whereas i.m. adipose tissue contained increased (P < 0.05) amounts of total PUFA. Results from this study indicate that short-term lipid supplementation to feedlot cattle can increase adipose tissue CLA concentrations, but only marginally (8.3 to 17.5%). Moreover, observed decreases in oleic acid and total MUFA concentrations of adipose tissues from heifers fed rumen-protected CLA or corn oil suggest that lipid supplementation may decrease delta9 desaturase activity in adipose tissues, which in turn would lower the conversion of TVA to cis-9, trans-11 CLA isomer.

Dietary Conjugated Linoleic Acids as Free Fatty Acids and Triacylglycerols Similarly Affect Body Composition and Energy Balance in Mice

The objective of this study was to compare the effects of conjugated linoleic acid (CLA) as triacylglycerols (TAG) or free fatty acids (FFA) on body composition and energy balance in mice. We fed four groups of 5-wk-old Balb-C mice (n = 9) semipurified diets containing either CLA (0.5 g CLA/100 g of diet) or high oleic sunflower oil (HOSF) in the form of FFA or TAG for 42 d. Body composition was determined and the energy in the carcasses, excreta and food was measured in a bomb calorimeter. The amount of body fat was 4.72 +/- 0.95 g (17.9 +/- 2.8%) in the HOSF-FFA group, 2.36 +/- 0.29 g (9.4 +/- 1.0%) in the CLA-FFA mice (mean +/- SD, P < 0.05), 4.76 +/- 0.74 g (18.2 +/- 2.2%) in the HOSF-TAG group and 2.32 +/- 0.38 g (9.3 +/- 1.1%) in the CLA-TAG mice (P < 0.05). The percentage of energy intake that was stored in the body was 3.5 +/- 1.2% in the HOSF-FFA group, 0.6 +/- 0.3% in the CLA-FFA group (P < 0.05), 3.5 +/- 1.1% in the HOSF-TAG group and 0.5 +/- 0.4 in the CLA-TAG mice (P < 0.05). Conversely, the percentage of energy intake that was expended as heat was 89.4 +/- 1.2% in the HOSF-FFA group, 92.4 +/- 0.8% in the CLA-FFA mice (P < 0.05), 89.47 +/- 1.23% in the HOSF-TAG group and 92.2 +/- 0.4% in the CLA-TAG group (P < 0.05). Thus, CLA in the form of FFA or TAG had similar effects on body composition and energy balance.