Conjugated Linoleic Acid Feeding Research Articles

Conjugated Linoleic Acid Is a Growth Factor for Rats as Shown by Enhanced Weight Gain and Improved Feed Efficiency ,

We studied the effect of conjugated linoleic acid (CLA) on rat development and growth. Primigravid female Fischer rats were fed control or CLA-supplemented (0.25% or 0.5% CLA) diets during gestation and/or lactation. Conjugated linoleic acid was incorporated into milk fat and tissue lipids proportional to the level of CLA fed and the duration of CLA feeding. Conjugated linoleic acid was incorporated into fetal and neonatal tissues; it did not affect litter size nor induce apparent abnormalities. To the contrary, feeding CLA to the dams during gestation and lactation improved the postnatal body weight gain of pups (P < 0.05), measured on d 10 of lactation. Pups that continued to receive the CLA-supplemented diet after weaning had significantly greater body weight gain and improved feed efficiency relative to control animals (P < 0.05).

Size, numberand phospholipid composition of milk fat globules are affected by dietary conjugated linoleic acid.

Milk fat globules (MFGs) surround the triacylglycerol core that composes milk fat. The aim of this study isto induce milk fat depression via dietary conjugated linoleic acid (CLA) supplementation to study MFG size parameters, numberand glycerophospholipid composition. Eighteen Holstein dairy cows (136 ± 28 days in milk, 571 ± 37.9 kg body weight, 27.6 ± 2.1 kg milk/day) were selected and randomly assigned to a control or CLA group for a 14-dayperiod. Cows were fed a basal diet (control, n = 8) or the control plus 400 g/day CLA (C18:2 cis-9, trans-11 38.1% and C18:2 trans-10, cis-12 36.8%) (n = 10) for 7 days after which the CLA group was switched to the basal diet for another 7 days along with the control group. Cow performance, milk composition, MFG size and numbers were measured daily. On the seventh day after the start of the experiment, milk samples were identified and the quantification of glycerophospholipid compounds, and RNA were isolated from milk fat samples for a real-time polymerase chain reaction. Compared with control, at Day 7 from the start of feeding, supplemental CLA did not affect milk production (28.09vs. 28.50 kg/day), dry matter intake (14.9vs. 15.4 kg/day), or milk protein (3.55/100vs. 3.70 g/100 ml) and lactose contents (5.11/100vs. 5.17 g/100 ml). However, although the specific surface area of MFG (2138vs. 1815 m²/kg) was greater, CLA reduced milk fat content (1.95/100vs 3.64 g/100 ml on Day 7) and particle size parameters of MFG. The number of MFG gradually decreased until Day 7 of feeding, and then increased by Day 14 (2.96 × 109 on Day 1, 1.63 × 109 on Day 7 and 2.28 × 109 on Day 14) in the CLA group. Compared with control, glycerophospholipid analysis revealed that concentrations of phosphatidylcholine (PC) (e.g., PC [16:0/18:1] 20322vs. 29793 nmol/L), lysophosphatidylethanolamine (LPE) (e.g., LPE [18:1] 956vs. 4610 nmol/L)and phosphatidylethanolamine (PE) (e.g., PE [16:0/18:1] 7000 vs. 9769 nmol/L) in milk lipids decreased during CLA feeding. In contrast, concentrations of phosphatidylinositol (PI) (e.g., PI [18:0/18:1] 4052vs. 1799 nmol/L) and phosphatidylserine (PS) (e.g., PS [18:1/18:2] 9500 vs. 6843 nmol/L) increased. The messenger RNA abundance of fatty acid synthase, diacylglycerol O-acyltransferase 1, glycerol-3-phosphate acyltransferase 4and phosphate cytidylyltransferase 1, choline, alpha (PCYT1A) were downregulated in the CLA group, confirming published data demonstrating a negative effect of CLA on lipogenesis in the mammary gland. Overall, these results provided evidence for the important role of lipogenic gene expression in the regulation of MFG size, number and glycerophospholipid composition.

EFFECT OF CONJUGATED LINOLEIC ACID FEEDING PERIODS ON FATTY ACID PROFILE AND NUTRITIONAL QUALITY OF &lt;i&gt;Astyanax altiparanae&lt;/i&gt;

The effects of feeding diets with conjugated linoleic acid (CLA) to Astyanax altiparanae for different periods were investigated on carcasses’ fatty acid profile and nutritional quality. The trial was laid out in a complete randomized design with eight feeding periods (0, 7, 14, 21, 28, 35, 42, and 49 days) and four replicates. A total of 240 fish (3.4 ± 0.3 g) were distributed into four aquariums and fed with the diet containing 32% crude protein, 15 MJ kg-1 gross energy, and 2.5% of CLA. Feeding CLA diet for 49 days resulted in the higher deposition of CLA, CLA isomers, and docosahexaenoic acid (DHA). The isomer c9,t11 was highly deposited than the t10,c12. Polyunsaturated fatty acids (PUFA), n-3, and n-6 increased with feeding period, whereas saturated (SFA), monounsaturated, and medium-chain fatty acids decreased. PUFA/SFA ratio, DHA/EPA, EPA+DHA, and thrombogenicity index increased linearly. Whereas atherogenicity index reduced, hypocholesterolemic/hypercholesterolemic ratio increased in quadratic effects over feeding time. No difference was observed for the n-6/n-3 ratio. Feeding A. altiparanae with 2.5% of CLA for a minimum of 35 days improves the fatty acid profile and provides a commercial product with good nutritional quality and functional benefits.

Effect of conjugated linoleic acid supplementation on fat globule size in raw milk

The effect of conjugated linoleic acid (CLA) on milk lipids and on the size of milk fat globules (MFGs) during milk fat depression in dairy cows was evaluated. Twelve Holstein cows were randomly assigned to a control diet or control plus Ca-protected CLA at 15 g kg−1 dry matter for an 8-day period. Feeding CLA did not affect milk production, dry matter intake or lactose level, but tended to reduced milk protein (−0.19%; P = 0.08) and reduced milk fat content (−1.39%; P < 0.01). Compared with the controls, the size of MFGs in cows fed CLA was lower, while their specific surface area was higher. CLA supplementation reduced the relative contents of phosphatidylcholine and phosphatidylethanolamine in milk fat.

Short communication: A decrease in diameter of milk fat globules accompanies milk fat depression induced by conjugated linoleic acid supplementation in lactating dairy cows

Milk fat is secreted from the mammary gland in the form of milk fat globules (MFG). Although milk fat depression has been studied since the beginning of the last century, the extent to which this phenomenon alters MFG synthesis is not fully understood. The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on the size and distribution of MFG during milk fat depression in dairy cows. Twelve Holstein cows in mid lactation (145 ± 31 d in milk, 583 ± 34.6 kg of body weight, and 27.2 ± 2.4 kg of milk/d) were randomly assigned to a control diet or control plus Ca-protected CLA at 15 g/kg of dry matter for a 6-d period. The average diameter and particle size distribution of MFG were measured using a Mastersizer 3000 laser particle size analyzer (Malvern Instruments Ltd., Malvern, UK). Feeding CLA did not affect dry matter intake (16.2 ± 0.4 kg/d), milk production (28.4 ± 0.4 kg/d), milk protein, or lactose, but it decreased milk fat content (3.46 vs. 2.52%). In addition, surface area-related mean diameter of fat globules in cows fed CLA was lower compared with controls (3.02 vs. 3.45 μm). The percentage of large fat globules decreased and that of small fat globules increased in response to CLA. Overall, the data suggest that the milk fat depression induced by CLA is accompanied by a decrease in average diameter of MFG.

Feeding Conjugated Linoleic Acid without a Combination of Medium-Chain Fatty Acids during Late Gestation and Lactation Improves Pre-Weaning Survival Rates of Gilt and Sow Progeny.

Simple SummaryA number of feeding strategies have been used in attempts to improve performance of progeny born to primiparous sows, which are born lighter, grow slower, and have higher rates of mortality than progeny born to older sows. The current study examined whether feeding conjugated linoleic acid (CLA) or a commercial medium-chain fatty acid (MCFA) product alone or in combination to primiparous and multiparous sows improved pre-weaning growth and survival of their progeny. Feeding CLA or MCFA failed to improve reproductive performance of primiparous or multiparous sows or the performance of their progeny during lactation, and there was no added benefit of feeding these products for gilt progeny. However, feeding CLA alone improved the survival of gilt and sow progeny. Further examination of the different inclusion levels and the timing of CLA feeding may be required in order for the use of this additive to be more efficacious.Feeding conjugated linoleic acid (CLA) or medium-chain fatty acids (MCFA) to dams has been shown to improve progeny growth and survival, and hence may be particularly advantageous to gilt progeny. Primiparous (n = 129) and multiparous sows (n = 123; parities 3 and 4) were fed one of four diets from day 107 of gestation (107.3 ± 0.1 days) until weaning (day 27.2 ± 0.1 of lactation): (i) control diet; (ii) 0.5% CLA diet; (iii) 0.1% MCFA diet; and (iv) equal parts of (ii) and (iii). Progeny performance data were collected and, from a subset of sows (n = 78) and their piglets (n = 144), a colostrum (day 0), milk (day 21), and piglet serum sample (day 3) were analyzed for immunoglobulin G and several selected metabolites. Liveborn pre-weaning mortality tended to be lowest (p = 0.051) in piglets from sows fed 0.5% CLA. However, sows fed the CLA diet had more (p = 0.005) stillbirths than those on the other diets. There were few effects of diet or the dam parity x diet interaction (p ≥ 0.05) on other parameters. Overall, feeding CLA or MCFA did not improve the performance of primiparous sows, multiparous sows, or their progeny.

Effect of dietary conjugated linoleic acid supplementation during late gestation on colostrum yield, fatty acid composition, and IgG concentrations in primiparous sows

This experiment was conducted to evaluate the effects of dietary conjugated linoleic acid (CLA) supplementation during late gestation on reproductive performance, colostrum yield, colostral fatty acid composition, and immunoglobulin G (IgG) concentrations in primiparous sows. Twenty-four primiparous Landrace × Large White pregnant sows were randomly selected and assigned to four dietary treatments: 0% (control), 0.75%, 1.50%, and 2.25% CLA supplementation from day 85 of gestation to parturition. During lactation, all sows were fed the same commercial diet. The preweaning mortality of suckling piglets born to dams fed supplemental CLA did decrease linearly (P = 0.01) during lactation. Administration of CLA during gestation increased linearly (P &lt; 0.01) total saturated fatty acids and decreased linearly (P &lt; 0.01) monounsaturated fatty acids and polyunsaturated fatty acids in colostrum. The concentrations of CLA isomers were higher (P &lt; 0.01) in colostrum from primiparous sows fed CLA diets than in the control group. Feeding CLA increased (P &lt; 0.05) colostral IgG concentrations, as well as that in the serum of neonatal piglets. In conclusion, 2.25% CLA supplementation in the diet of primiparous sows during late gestation could improve the passive immunity through colostral IgG and the survival of suckling piglets.

Effect of conjugated linoleic acid supplementation during the transition period on plasma metabolites and productive and reproductive performances in dairy cows

The objective of this study was to determine the effects of dietary conjugated linoleic acid (CLA) supplementation during the transition period on plasma metabolites and productive and reproductive performance in dairy cows. Seventy five multiparous Holstein cows approximately 3 weeks before expected calving date were randomly assigned to 1 of 4 diets containing: (1) CLA21 (n=18), rumen protected CLA (75g/h/d, Lutrell Pure, BASF, Ludwigshafen, Germany) from 21 d before parturition (dbp) to 21 d postpartum (dpp); (2) CLA42 (n=19), rumen protected CLA from 21dbp to 42dpp; (3) PO21 (n=18), palm oil (75g/h/d) from 21dbp to 21dpp; or (4) PO42 (n=20), palm oil from 21dbp to 42dpp. Daily milk yield and body condition score (BCS) at calving and 42dpp were recorded. Milk fat, protein and lactose were determined weekly. Blood samples were collected from 8 cows in each dietary group at 20.2±3.2 (mean±SEM), 0, 10, 21 and 42 d relative to calving (day 0) to determine plasma concentration of glucose, cholesterol, triglyceride, high density lipoprotein (HDL), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA) and insulin. Milk yield was greater in cows fed diets supplemented with CLA compared to those fed PO diets, conversely overall milk fat content and fat yield was lower in cows fed CLA compared to those fed diets supplemented with PO. There were no differences among diets for dry matter intake (DMI). Cows in CLA21and those in PO42 dietary treatments had the least and greatest BCS loss, respectively from calving until 42dpp. Plasma concentrations of glucose and cholesterol were greater in CLA fed cows compared with PO fed cows. Plasma NEFA and BHBA were lower in PO21 and CLA21 cows than in PO42 and CLA42 cows. However, dietary treatment had no effect (P≥0.05) on plasma concentration of triglyceride, HDL, SGOT, SGPT and insulin. In addition, reproductive performance did not differ among dietary groups. In summary, feeding CLA during transition period decreased milk fat percentage, BCS loss and increased plasma concentrations of glucose and cholesterol, and milk yield. Extending supplementation of either CLA or PO from 21 to 42dpp increased plasma concentrations of BHBA and NEFA, but did not alter milk composition and yield. Reproductive performance of dairy cows did not differ among dietary treatments.

Effect of feeding CLA on plasma and granules fatty acid composition of eggs and prepared mayonnaise quality

Eggs rich in trans, trans conjugated linoleic acid (CLA) are significantly more viscous, have more phospholipids containing linoleic acid (LA), and more saturated triacylglycerol species than control eggs. However, the fatty acid (FA) composition of yolk plasma and granule fractions are unreported. Furthermore, there are no reports of mayonnaise rheological properties or emulsion stability by using CLA-rich eggs. Therefore, the objectives were (1) compare the FA composition of CLA-rich yolk granules and plasma, relative to standard control and LA-rich control yolks, (2) compare the rheological properties of mayonnaise prepared with CLA-rich eggs to control eggs and (3) compare the emulsion stability of CLA-yolk mayonnaise. CLA-rich eggs and soy control eggs were produced by adding 10% CLA-rich soy oil or 10% of control unmodified soy oil to the hen’s diet. The eggs were used in subsequent mayonnaise preparation. CLA-yolk mayonnaise was more viscous, had greater storage modulus, resisted thinning, and was a more stable emulsion, relative to mayonnaise prepared with control yolks or soy control yolks.

Short communication: Effect of conjugated linoleic acid on concentrations of fat-soluble vitamins in milk of lactating ewes

Conjugated linoleic acids (CLA) are well known as milk fat-reducing feed supplements in diets for lactating ruminants. However, their effects on milk concentrations of fat-soluble vitamins are unknown. This study was performed to investigate the hypothesis that CLA affect the concentrations of retinol and tocopherol in ewe milk. For that purpose, group-housed Merino ewes (101±13.7kg) nursing twin lambs and fed with a hay:concentrate diet were supplemented with either 45g of a rumen-protected CLA supplement containing 3.4g of cis-9,trans-11-CLA and 3.4g of trans-10,cis-12-CLA (CLA group, n=11) or with 45g of a hydrogenated vegetable fat (control group, n=12) per ewe per day during the first 6 wk of lactation. Feed intake was recorded daily (concentrate) or weekly (hay) per group. Milk spot samples were collected at the beginning of the experiment (5±2.4 d postpartum) and then weekly after lambs had been separated for 2 h from their mothers. The milk fat content was determined and feed and milk were analyzed for concentrations of α-, γ-, and δ-tocopherol and for retinol by HPLC. Dietary intake of tocopherol and retinol was similar in both groups. Feeding CLA decreased milk fat concentration by 23% on average, and during the first 3 wk of the study milk tocopherol concentration tended to be increased by feeding CLA (+17%), but retinol concentrations were not influenced. When related to milk fat, CLA feeding significantly increased both milk tocopherol (+40%) and retinol (+32%) and these effects were evident during the whole experimental period corresponding to the first half of lactation.

Effects of Early Administration of Conjugated Linoleic Acid on Development of Obesity in NescientBasic Helix‐Loop‐Helix 2 Knockout Mice

Childhood obesity has steadily increased in the past 30 years and is associated with increased risk of chronic metabolic diseases. This study aimed to determine effects of conjugated linoleic acid (CLA) exposure during growth period on development of inactivity-induced obesity by investigating the molecular targets on skeletal muscle in nescient basic helix-loop-helix 2 knock-out (N2KO) mice, a unique adult-onset inactivity induced obesity model. 4-week-old male N2KO and wild-type mice were fed either control or CLA containing diet (0.5%) for 4-weeks, and then all animals were fed control diet for 8-weeks. Voluntary activity and glucose tolerance were examined every 4 weeks and markers for muscle energy metabolism were determined from the gastrocnemius. CLA fed wild-type animals significantly prevented a reduction of voluntary activity and glucose intolerance compared to control groups at week 12. CLA feeding up-regulated AMP-activated protein kinase (AMPK) activation, peroxisome proliferator-activated receptor gamma co-activator 1a (PGC-1a, a master regulator of mitochondrial biogenesis), peroxisome proliferator-activated receptor-δ (PPARd) and mitochondrial transcription factor A (Tfam) in wild-type animals compared to controls, but not in obese animals. These results suggest that early exposure to CLA during growth modulates muscle energy metabolism via enhancing mitochondriogenic factors, resulting in increased voluntary activity and improved glucose metabolisms in normal animals, but not in genetically predisposed obese mice.

Rosiglitazone, a PPAR-γ agonist, fails to attenuate CLA-induced milk fat depression and hepatic lipid accumulation in lactating mice.

Our objective was to investigate the combination of rosiglitazone (ROSI) and conjugated linoleic acid (CLA) on mammary and hepatic lipogenesis in lactating C57Bl/6 J mice. Twenty-four lactating mice were randomly assigned to one of four treatments applied from postpartum day 6 to day 10. Treatments included: (1) control diet, (2) control plus 1.5 % dietary CLA (CLA) substituted for soybean oil, (3) control plus daily intra-peritoneal (IP) rosiglitazone injections (10 mg/kg body weight) (ROSI), and (4) CLA plus ROSI (CLA-ROSI). Dam food intake and milk fat concentration were depressed with CLA. However, no effects were observed with ROSI. The CLA-induced milk fat depression was due to reduced expression for mammary lipogenic genes involved in de-novo fatty acid (FA) synthesis, FA uptake and desaturation, and triacyglycerol synthesis. Liver weight (g/100 g body weight) was increased by CLA due to an increase in lipid accumulation triggering a compensatory reduction in mRNA abundance of hepatic lipogenic enzymes, including acetyl-CoA carboxylase I and stearoyl-CoA desaturase I. On the contrary, no effects were observed with ROSI on hepatic and mammary lipogenic gene and enzyme expression. Overall, feeding CLA to lactating mice induced milk fat depression and increased hepatic lipid accumulation, probably due to the presence of trans-10, cis-12 CLA isomer, while ROSI failed to significantly attenuate both hepatic steatosis and reduction in milk fat content.

Molecular mechanisms of conjugated linoleic acid (CLA) on muscle metabolism in adult onset inactivity‐induced obese mice (1045.46)

Conjugated linoleic acid (CLA) has been reported to increase voluntary activities in mice. Current study was conducted to investigate how CLA modulates activity levels by determining the molecular targets on skeletal muscle in nescient basic helix‐loop‐helix 2 knock‐out (N2KO) mice, a unique adult‐onset inactivity induced obesity model. 4‐week‐old female N2KO and wild‐type mice were fed either control or CLA containing diet (0.5%) for 10‐weeks. Non‐exercise physical activity (NEPA) was determined biweekly and markers for muscle metabolisms were determined from the gastrocnemius. CLA fed N2KO animals showed significant increase of NEPA (~40%) from 6 weeks compared to controls. The gastrocnemius weights were lower in N2KO animals compared to wild types, while CLA supplementation resulted in heavier the gastrocnemius over controls in N2KO animals. Protein expressions for peroxisome proliferator‐activated receptor‐δ (PPARδ) and peroxisome proliferator‐activated receptor gamma co‐activator 1α (PGC‐1α) in the gastrocnemius were increased in CLA fed N2KO animals compared to controls, 65% and 38% increase, respectively. CLA feeding increased pAMPK/AMPK ratio, 36% increase, compared to controls. These results suggest that CLA act as a potential exercise‐mimetic, resulting in increased voluntary activity and improving muscle metabolisms in both normal and obese animals.

Conjugated linoleic acid promotes endurance capacity via SIRT1 and AMPK mediated mechanisms (37.3)

Previously it was reported that conjugated linoleic acid (CLA) and exercise training improves endurance capacity potentially via peroxisome proliferator‐activated receptor δ (PPARδ)‐mediated mechanism in mice. Based on these results, the current study was designed to determine the role of exercise and/or CLA in improved endurance capacity and upstream regulator(s) for PPARδ. Male 129Sv/J mice were fed either control or CLA (0.5%) containing diet for 4 weeks and further divided into sedentary or training regime (25 min three times per week). Consistent with previous observations, CLA feeding significantly reduced body weight and fat mass independent of excise during the experimental period. Endurance capacity was significantly improved by CLA treatment, while there was no significant effect of training alone. Similarly, CLA treatment significantly increased expression of peroxisome proliferator‐activated receptor gamma coactivator 1‐α (PGC1α), an upstream regulator of PPARδ, in both sedentary and trained animals, 58% and 28%, respectively. It was further determined that CLA influences silent information regulation 2 homolog‐1 (SIRT1) and AMP‐activated protein kinase (AMPK) regardless of activity levels, which are upstream regulators of PGC1α. These results suggest that CLA improves exercise outcome independent of activity levels via SIRT1 and AMPK mediated mechanisms.

Effect of Conjugated Linoleic Acid Feeding on the Growth Performance and Meat Fatty Acid Profiles in Broiler: Meta-analysis.

The effect of conjugated linoleic acid (CLA) feeding on growth performance and fatty acid profiles in thigh meat of broiler chicken was investigated using meta-analysis with a total of 9 studies. Overall effects were calculated by standardized mean differences between treatment (CLA fed) and control using Hedges’s adjusted g from fixed and random effect models. Meta-regression was conducted to evaluate the effect of CLA levels. Subgroups in the same study were designated according to used levels of CLA, CP levels or substituted oils in diets. The effects on final body weight, weight gain, feed intake and feed conversion ratio were investigated as growth parameters. Total saturated and unsaturated fatty acid concentrations and C16:0, C18:0, C18:2 and C18:3 concentrations in thigh meat of broiler chicken were used as fatty acid profile parameters. The overall effect of CLA feeding on final weight was negative and it was only significant in fixed effect model (p<0.01). Significantly lower weight gain, feed intake and higher feed conversion ratio compared to control were found (p<0.05). CLA feeding on the overall increased total saturated fatty acid concentration in broilers compared to the control diet (p<0.01). Total unsaturated fatty acid concentration was significantly decreased by CLA feeding (p<0.01). As for individual fatty acid profiles, C16:0, C18:0 and C18:3 were increased and C18:2 was significantly decreased by CLA feeding (p<0.01). In conclusion, CLA was proved not to be beneficial for improving growth performance, whereas it might be supposed that CLA is effective modulating n-6/n-3 fatty acids ratio in thigh meat. However, the economical compensation of the loss from suppressed growth performance and increased saturated fatty acids with the benefit from enhanced n-6/n-3 ratio should be investigated in further studies in order to propose an appropriate use of dietary CLA in the broiler industry.

A dietary conjugated linoleic acid treatment that slows renal disease progression alters renal cyclooxygenase-2-derived prostanoids in the Han: SPRD-cy rat

A mixture of dietary conjugated linoleic acid (CLA) isomers reduces inflammation and mitigates disease progression in the Han:SPRD-cy rat model of chronic kidney disease. Since cyclooxygenase (COX) activities and prostanoid levels are higher in diseased kidneys in this rat, and dietary CLA can inhibit COX2 and prostanoid production in other tissues, the effects of dietary CLA were investigated. Kidney homogenates from normal and diseased Han:SPRD-cy rats were analyzed for prostanoid levels under various conditions: endogenous levels, steady-state levels (60-min incubations) and produced by COX isoforms. Thromboxane B2 (TXB2; TXA2 metabolite), 6-keto-prostaglandin F1α (6-keto-PGF1α; PGI2 metabolite) and PGE2 levels under these conditions were two- to ninefold higher in diseased kidneys. Dietary CLA resulted in ∼32%–53% lower levels of prostanoids produced by total COX and COX2 activities in normal and diseased kidneys and partially mitigated alterations in COX2 protein levels associated with disease. The COX1 protein and activity were higher in renal disease, resulting in increased production of TXB2 and 6-ketoPGF1α, but not PGE2. Dietary CLA had no effect on COX1, however. Disease resulted in up to twofold higher ratios of TXB2/6-ketoPGF1α, TXB2/PGE2 and 6-ketoPGF1α /PGE2, and dietary CLA partially mitigated these increases under several conditions. Elevated levels of renal membrane associated cytosolic phospholipase A2 in diseased kidneys also were reduced by 50% with CLA feeding. The effects of CLA feeding on COX2 protein levels and activity indicate that the beneficial effect of dietary CLA in this renal disorder is mediated in part via effects on COX2-derived prostanoids.

Effect of a rumen‐protected conjugated linoleic acid mixture on hepatic lipid metabolism in heifers

This study was performed to assess the effects of rumen-protected conjugated linoleic acid (CLA) on hepatic lipid metabolism in heifers. In particular, it was of interest whether feeding CLA causes development of fatty liver as observed recently in mice. Thirty-six growing heifers with an initial body weight of 185 kg were allotted to three treatment groups and fed daily 250 g of different rumen-protected fats for 16 weeks: The control group received 250 g of a CLA-free control fat, the CLA100 group received 100 g of a CLA fat containing 2.4% of cis-9, trans-11 CLA and 2.1% of trans-10, cis-12 CLA and 150 g control fat and the CLA250 group received 250 g of the CLA fat. CLA supplementation had no effect on animal performance parameters, liver weight and hepatic triglyceride concentration. Moreover, mRNA expression of hepatic genes involved in lipogenesis, β-oxidation and fatty acid transport was not influenced by dietary CLA. The fatty acid composition of hepatic total lipids, with particular consideration of ratios of fatty acids indicative of Δ9-, Δ6- and Δ5-desaturation, was also less influenced by dietary CLA. In conclusion, the study shows that dietary rumen-protected CLA has less effect on hepatic lipid metabolism in young heifers and does not induce the development of a fatty liver such as in mice.

Time‐dependent effect of conjugated linoleic acid‐induced body fat loss and lipolysis in coconut oil fed mice

Dietary conjugated linoleic acid (CLA) causes a body fat loss that is enhanced when mice are fed coconut oil (CO). The objective was to determine if there is a time-dependent effect of CLA feeding on lipolysis. Male mice (ICR; n=80; 3wk-old) were fed 7% SO or CO diets for 6wk then 0 or 0.5% CLA for 3, 7, 10 or 14d. A body fat index (BFI) was calculated and lipolysis was determined ex vivo by NEFA and glycerol release from adipose tissue. The relative expression of perilipin and phosphorylated perilipin (P-perilipin) were determined by western blotting. The BFI was reduced by CO on d7 (P<0.01), and by both CLA (P<0.05) and CO (P<0.05) on d14. NEFA release was increased by CLA in CO-fed mice (1.84 vs 7.93 μmol/g; P<0.01) but not in SO-fed mice (1.64 vs 2.03 μmol/g) on d7 but on d14 CLA increased NEFA release in both CO (2.83 vs 6.16 μmol/g) and SO-fed mice (2.01 vs 4.99 μmol/g). Glycerol release was increased by CLA in CO-fed mice but not in SO-fed mice on d3 and d7 (P<0.05). P-perilipin was not altered by diet but total perilipin tended to be increased by CLA in CO-fed mice (P=0.055) on d7. Therefore CLA-induced lipolysis may occur more rapidly in CO vs SO-fed mice but appears to be transitory.

Effect of dietary CLA administration on fatty acid composition and lipogenic and lipolytic enzyme activities in suckling and weaned piglets

The objective of this study was to determine the effects of conjugated linoleic acid (CLA) administration during the lactation and post-weaning period or in the post-weaning period exclusively on fatty acid (FA) composition and enzymatic regulation in suckling and in 63-d-old piglets. During the nursery phase, 18 piglets individually penned were used and three dietary treatments ( n = 6) were applied: (1) piglets that proceeded from control sows fed a control diet (0 g CLA/kg) (CT-CT), (2) piglets from control sows fed a diet containing 10 g CLA/kg (CT-CLA) and (3) piglets from CLA fed sows fed diets containing 10 g CLA/kg (CLA-CLA). Suckling piglets (28 d of age) from sows fed the CLA enriched diet showed higher concentration of saturated FA (SFA), lower concentration of total monounsaturated FA (MUFA) and lower MUFA/SFA, C16:1 n-7/C16:0 and C18:1 n-9/C18:0 ratios in subcutaneous backfat than those from sows fed the control diet ( P<0.05). No CLA isomers were detected at weaning in the subcutaneous backfat of piglets from sows fed the control diet, but 0.44 g/100 g total FA (TFA) c9, t11-CLA and 0.12 g/100 g TFA t10, c12-CLA were observed in piglets from CLA fed sows. Also, increased c9, t11-CLA, t10, c12-CLA and SFA proportions ( P<0.05) and decreased MUFA and MUFA/SFA and C16:1 n-7/C16:0 ratios were found in the liver of piglets from CLA fed sows ( P<0.05). In 63-d-old piglets, malic enzyme activity in subcutaneous fat was lower in groups in which CLA was fed to sows and piglets or only to piglets than in the group that did not receive any CLA supplementation ( P<0.05). No effect of dietary CLA on heart L-3-hydroxyacyl-CoA dehydrogenase and glucose-6-phosphate dehydrogenase and malic enzyme activity in liver was observed. The concentration of c9, t11-CLA and t10, c12-CLA at weaning was negligible in piglets from sows fed the control diet, but after being fed for 35 d the diet enriched with CLA, the concentration was similar to that of piglets fed milk and diet containing CLA. Little alteration of enzyme regulation induced by CLA feeding was found in piglets either at 28 or 63 d of age, except for malic enzyme activity, which was lower in 63-d-old piglets fed the CLA enriched diet after weaning.

Interaction between dietary conjugated linoleic acid and calcium supplementation affecting bone and fat mass

Dietary conjugated linoleic acid (CLA) has shown wide biologically beneficial effects, such as anticancer, antiatherosclerotic, antidiabetic, immunomodulating, and antiobesity effects. However, the effects of CLA on total body ash, reflective of bone mineral content, have not been consistent. We hypothesized that the inconsistency of the CLA effect on ash may be linked to interaction between CLA and dietary calcium levels. Thus, we investigated the effects of CLA on body ash in conjunction with various calcium levels. Male ICR mice were fed three different levels of calcium (0.01, 0.5, and 1%) with or without 0.5% CLA for 4weeks for Experiment 1 and separate CLA isomers at 0.22% level with 1% calcium in Experiment 2. CLA feeding reduced body fat regardless of dietary calcium level, whereas CLA supplementation increased body ash compared to control only in animals fed the 1% calcium. In Experiment 2 it was confirmed that this observation was associated with the trans-10, cis-12 CLA isomer, but not with the cis-9, trans-11 isomer. CLA administration with 1% dietary calcium significantly improved total ash percent (%) in femurs, confirming that CLA has the potential to be used to improve bone mass.