The Effect of Nonstructural Carbohydrate and Addition of Full Fat Extruded Soybeans on the Concentration of Conjugated Linoleic Acid in the Milk Fat of Dairy Cows
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Conjugated linoleic acid (CLA), a naturally occurring anticarcinogen found in dairy products, is a byproduct of incomplete ruminal biohydrogenation of unsaturated fatty acids. Our objective was to determine the effect of nonstructural carbohydrate sources, addition of full fat extruded soybeans as a source of unsaturated fatty acids, and possible interactions on the milk fat content of CLA. Cows (n = 20) were assigned to a 4 x 4 Latin square involving two sources of nonstructural carbohydrate, high starch (corn) or high pectin (citrus pulp), with or without addition of extruded soybeans. Milk yield was not affected by nonstructural carbohydrate source, but milk production was increased by 7.8 to 10.5% with dietary additions of extruded soybeans. Milk fat content did not differ between treatments, but fatty acid composition was affected. Cows fed extruded soybean diets had reduced concentrations of C8 to C16 fatty acids and increased concentrations of octadecenoic acids. Diets with extruded soybeans also resulted in more than a doubling in milk fat concentration and yield of CLA. Nonstructural carbohydrate source had only minor effects on CLA, and there was no interaction with extruded soybeans. Milk fat content of trans-C18:1 and CLA were closely related (r2 = 0.77). However, variation among cows was about threefold for each of the diets and rank order of individual cows differed among diets. Overall, we demonstrated that diet modification can be used to alter CLA content of milk fat, but there was substantial individual cow variation for all diets.Vaccenic acid
Animal fat
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The purpose of this paper is to evaluate nutritional strategies that will increase the concentration of the conjugated linoleic acid in milk to produce functional milk with regard to health benefits in dairy cow. Conjugated linoleic acid isomers are naturel fatty acids in foods obtained from ruminants.The main substrates for biohydrogenation are linoleic acid and linolenic acid, an essential fatty acid. It has been identified 54 different conjugated linoleic acid isomers that have beneficial biological activity. cis -9, trans -11 18:2 and trans -10, cis -12 18: are most bioactive isomers of CLA. In milk fat, the cis -9, trans -11 conjugated linoleic acid is found in major amounts more than trans -10, cis -12 conjugated linoleic acid. Conjugated linoleic acid is first produced as an intermediate product during the biohydrogention in the rumen of dietary linoleic acid and linolenic acid. Another major pathway of conjugated linoleic acid synthesis in dairy cows is endogenous synthesis in the mammary gland. Dietary cis -9, trans -11 conjugated linoleic acid is of great interest due to its health benefits known to a cancer chemopreventive and antiatherogenic. Therefore, many researchers have looked for ways of increasing the amount of conjugated linoleic acid in cow milk. For this pupurpose, researchers have adopted two approaches. The first approach is to make dietary changes to increased the natural conjugated linoleic acid production of cow. The second approach is to feed with mixtures of conjugated linoleic acid isomers protected against microbial biological hydrogenation in the rumen. As a result, as consumers continue to be aware of the relationship between diet and health, increased conjugated linoleic acid level of milk may provide new market opportunities for milk and milk products as functional food.
Linolenic acid
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Abstract To assess the oxidative metabolism of conjugated linoleic acid (CLA) isomers, rats were force‐fed 1.5–2.6 MBq of [1‐ 14 C]‐linoleic acid (9 c ,12 c ‐18∶2),‐rumenic acid (9 c ,11 t ‐18∶2), or‐10 trans , 12 cis ‐18∶2 (10 t , 12 c ‐18∶2), and 14 CO 2 production was monitored for 24 h. The animals were then necropsied and the radioactivity determined in different tissues. Both CLA isomers were oxidized significantly more than linoleic acid. Moreover, less radioactivity was recovered in most tissues after CLA intake than after linoleic acid intake. The substantial oxidation of CLA isomers must be considered when assessing the putative health benefits of CLA supplements.
Lipidology
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Background and purpose: Due to the beneficial physiological effects of conjugated linoleic acid (CLA), there has been a growing tendency to produce it as a functional lipid in recent years. Different CLA isomers have different physiological effects; hence, production of certain CLA isomers with high purity is of great importance. CLA can be produced through both chemical and enzymatic methods; however, unlike chemical catalysts, enzymes make it possible to produce pure CLA isomers. In this study, linoleic acid isomerase from Propionibacterium acnes was expressed in E. coli and the possibility of the production of CLA was studied. Materials and methods: The vector containing linoleic acid isomerase, pGEX-6P-PAI, was transformed in E. coli . Transformants were selected based on their resistance to ampicillin and restriction digestion analysis. To express the recombinant linoleic acid isomerase, transformants were induced using isopropyl-beta-thiogalactopyranoside (IPTG). The expression of recombinant protein was confirmed by SDS-polyacrylamide gel electrophoresis and Western blotting using anti-linoleic acid isomerase antibody. Then, the possibility of the production of CLA from Linoleic acid by using E-coli transformant was investigated. Results: Recombinant linoleic acid isomerase was intracellularly produced as a glutathione Stransferase (GST) tagged protein by transformed E-coli. The fusion of GST to the N-terminus of linoleic acid isomerase increased its molecular weight from 49 to 75 kDa. GST-tagged enzyme acted like linoleic acid isomerase and the transformed bacterium could convert considerable amounts of linoleic acid to CLA. Conclusion: The findings indicated that transformed E. coli can be used for CLA production in biocatalytic processes.
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Cis–trans isomerism
Stearic acid
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Two strains that can transform linoleic acid to conjugated linoleic acid were screened from soil.The morphology,growth curves and the optimum conditions for CLA production in MRS medium were studied in this paper.Though the two strains were different significantly in morphology,the optimum conditions for CLA production of them were similar: concentration of linoleic acid was 0.51%(v/v),and incubation time was 36～48 h.
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Conjugated linoleic acid is a collective term used to designate a mixture of positional and geometric isomers of linoleic acid in which the double bonds are conjugated. Unlike linoleic acid, there is a paucity of information regarding the effect of dietary conjugated linoleic acid on plasma lipoproteins and aortic atherosclerosis. Therefore, fifty hamsters were divided into five groups of ten and fed 0 (Control), 0.06 (LOW), 0.11 (MEDIUM), and 1.1 (HIGH) en% conjugated linoleic acid or 1.1 en% linoleic acid. Blood samples were taken at 4, 8 and 11 weeks for plasma lipid analyses and for plasma tocopherol assay at sacrifice. Animals fed the conjugated linoleic acid-containing diets collectively had significantly reduced levels of plasma total cholesterol, non-high density lipoprotein cholesterol, (combined very low and low density lipoprotein) and triglycerides with no effect on high density lipoprotein cholesterol, as compared to CONTROLs. Linoleic acid-fed animals relative to CONTROLs also had reduced plasma total cholesterol, non-high density lipoprotein cholesterol and triglycerides, but only the latter was statistically significant. Compared to the CONTROL group, plasma tocopherol/total cholesterol ratios determined from plasma pools for the LOW, MEDIUM and HIGH conjugated linoleic acid and linoleic acid groups were increased by 48%, 48%, 86% and 29%, respectively, suggesting a tocopherol-sparing effect, at least for the conjugated linoleic acid treatment. Morphometric analysis of aortas revealed less early atherosclerosis in the conjugated linoleic acid and linoleic acid-fed hamsters compared to the CONTROL group.
Low-density lipoprotein
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Abstract After screening 14 genera of lactic acid bacteria, Lactobacillus plantarum AKU 1009a was selected as a potential strain for CLA production from linoleic acid. Washed cells of L. plantarum with high levels of CLA production were obtained by cultivation in a nutrient medium with 0.06% (wt/vol) linoleic acid ( cis ‐9, cis ‐12‐octadecadienoic acid). Under the optimal reaction conditions with the free form of linoleic acid as the substrate, washed cells of L. plantarum produced 40 mg CLA/mL reaction mixture (33% molar yield) from 12% (wt/vol) linoleic acid in 108 h. The resulting CLA was a mixture of two CLA isomers, cis ‐9, trans ‐11 (or trans ‐9, cis ‐11)‐octadecadienoic acid (CLA1, 38% of total CLA) and trans ‐9, trans ‐11‐octadecadienoic acid (CLA2, 62% of total CLA), and accounted for 50% of the total FA obtained. A higher yield (80% molar yield to linoleic acid) was attained with 2.6% (wt/vol) linoleic acid as the substrate in 96 h, resulting in CLA production of 20 mg/mL reaction mixture [consisting of CLA1 (2%) and CLA2 (98%)] and accounting for 80% of total FA obtained. Most of the CLA produced was associated with the cells ( ca . 380 mg CLA/g dry cells), mainly as FFA.
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