Conjugated linoleic acid is synthesized endogenously in lactating dairy cows by Delta(9)-desaturase.
J. M. Griinari,Benjamin A. Corl,Shannon H. Lacy,P. Y. Chouinard,K. V. V. Nurmela,Dale E. Bauman +5 more
TLDR
Results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.Abstract:
Conjugated linoleic acid (CLA) is a naturally occurring anticarcinogen found in milk fat and body fat of ruminants. Although CLA is an intermediate in ruminal biohydrogenation of linoleic acid, we hypothesized that its primary source was from endogenous synthesis. This would involve Delta(9)-desaturase and synthesis from trans-11 18:1, another intermediate in ruminal biohydrogenation. Our first experiment supplied lactating cows (n = 3) with trans-11 18:1 by abomasal infusion and examined the potential for endogenous synthesis by measuring changes in milk fat CLA. By d 3, infusion of trans-11 18:1 resulted in a 31% increase in concentration of cis-9, trans-11 CLA in milk fat, demonstrating that an active pathway for endogenous synthesis of CLA exists. Our second experiment examined the quantitative importance of endogenous synthesis of CLA in lactating cows (n = 3) by abomasally infusing a putative stimulator (retinol palmitate) or an inhibitor (sterculic oil) of Delta(9)-desaturase. Infusion of retinol palmitate had no influence on milk fatty acid desaturation, and yield of CLA in milk fat was not altered. However, sterculic oil infusion decreased the concentration of CLA in milk fat by 45%. Consistent with Delta(9)-desaturase inhibition, the sterculic oil treatment also altered the milk fat concentration of other Delta(9)-desaturase products as indicated by the two- to threefold increase in the ratios of 14:0 to 14:1(,) 16:0 to 16:1 and 18:0 to cis-18:1. Using changes in the ratio of 14:0 to 14:1 as an indication of the extent of Delta(9)-desaturase inhibition with the sterculic oil treatment, an estimated 64% of the CLA in milk fat was of endogenous origin. Overall, results demonstrate that endogenous synthesis of CLA from trans-11 18:1 represented the primary source of CLA in milk fat of lactating cows.read more
Citations
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Nutritional regulation of milk fat synthesis.
Dale E. Bauman,J. Mikko Griinari +1 more
TL;DR: A more complete identification of these naturally produced inhibitors of fat synthesis and delineation of cellular mechanisms may offer broader opportunities for application and understanding of the regulation of lipid metabolism.
Journal ArticleDOI
The Composition of Bovine Milk Lipids: January 1995 to December 2000
TL;DR: Improved gas-liquid and high performance liquid chromatography were used and data on the trans and cis isomers of fatty acid and of conjugated linoleic acids are given, and the analyses are described.
Journal ArticleDOI
Dietary conjugated linoleic acid in health: physiological effects and mechanisms of action.
TL;DR: Health benefits, metabolism, and potential mechanisms of action of CLA are focused on and the implications regarding dietary CLA for human health are postulated.
Journal ArticleDOI
Innovations in beef production systems that enhance the nutritional and health value of beef lipids and their relationship with meat quality.
Nigel D. Scollan,Jean-François Hocquette,Karin Nuernberg,Dirk Dannenberger,Ian Richardson,Aidan P. Moloney +5 more
TL;DR: Strategies for increasing the content of beneficial omega-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) and reducing saturated fatty acid (SFA) in beef are reviewed and opportunities exist to enhance thecontent of health promoting fatty acids in beef and beef products offering opportunities to add value and contribute to market differentiation.
Journal ArticleDOI
Diet, rumen biohydrogenation and nutritional quality of cow and goat milk fat
TL;DR: More studies in rodents and humans fed dairy products modified by changing ruminant diet are required before recommending a larger use of lipid sources and how to combine them with the different feeding systems used by dairy farmers.
References
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Biosynthesis of conjugated linoleic acid and its incorporation into meat and milk in ruminants.
J. M. Griinari,Dale E. Bauman,M. P. Yurawecz,M. M. Mossoba,John K. G. Kramer,Michael W. Pariza,G. Nelson +6 more
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Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis.
TL;DR: Results demonstrate that trans-10,cis-12 CLA is the isomer responsible for inhibition of milk fat synthesis, and de novo synthesized fatty acids were extensively reduced.
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Trans-Octadecenoic Acids and Milk Fat Depression in Lactating Dairy Cows
TL;DR: Dietary fiber concentration and type of fat had significant effects on milk fat, and the addition of unsaturated fat resulted in marked increases in the milk fat content of trans-11-octadecenoic acid, regardless of dietary fiber concentration; however, marked milk fat depression occurred only when the low fiber diet was supplemented with uns saturated fat.
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Mechanism of rat liver microsomal stearyl-CoA desaturase. Studies of the substrate specificity, enzyme-substrate interactions, and the function of lipid.
TL;DR: Inhibition and analog studies suggest that the methylene chain of stearyl-CoA assumes an eclipsed ("gauche") conformation at carbon atoms 9,10 in the enzyme-substrate complex of desaturase, and isotope rate effects obtained with deuterated st earyl- CoA derivatives indicate that hydrogen removal is the rate-limiting step of desaturation.