Abstract
The influence of 1.2 ppm dietary selenium added in the form of selenized yeast (Se-yeast) and of a mixture of conjugated linoleic acid (CLA) isomers added to a level of 1 or 2%, of cis9trans11CLA (c9t11) added to 1%, and of trans10cis12CLA (t10c12) added to 1% on the body and organ gains of rats and on the concentration of CLA isomers and other fatty acids in the spleen, pancreas and kidneys was investigated. Total fatty acids in the studied organs were separated as methyl esters using long-capillary gas-liquid chromatography with flame-ionization detection, while nonmethylated fatty acids containing conjugated double bonds were examined using silver-ion liquid chromatography with fotodiode detection. Free fatty acids were obtained by mild saponification, whereas their methyl esters, by base- and acid-catalyzed methylation. Feeding t10c12 and Se-yeast resulted in the highest increase in rat growth and organ gain. All diets enriched in CLA isomer(s) significantly elevated the concentration of CLA isomers in the organs; the highest concentration of CLA isomers was found in the pancreas, the smallest, in the spleen. The addition of Se to diets containing CLA isomer(s) usually showed a statistical tendency or increase in the concentration of CLA isomers in the organs. Our results demonstrate that t10c12 was metabolized faster than c9t11 in the pancreas and kidneys, whereas the addition of Se-yeast to the diets with CLA isomer(s) reduced the rate of t10c12 metabolism. A 2% dietary content of a mixture of CLA isomers or of t10c12 usually tended to increase or significantly increased the concentration of linoleic, linolenic, and arachidonic acids and of n-3 long-chain polyunsaturated fatty acids (n-3 PUFA) in the organs. Dietary c9t11 and a 1% content of the mixture of CLA isomers weakly influenced the concentrations of these fatty acids in the organs, whereas the diet enriched simultaneously in c9t11 and Se-yeast resulted in a statistical tendency or increase in the concentration of long-chain n-3 PUFA and the
Highlights
The term conjugated linoleic acid (CLA) isomers refers to a collection of positional and geometric isomers of octadecadienoic acid with conjugated double bonds
As can be seen from these results, the diet enriched in the t10c12 isomer and Se-yeast most efficiently elevated the body weight gain (BWG) of rats and the weight of the pancreas and kidneys of rats compared with animals fed the diet supplemented with only Se-yeast as well as with the control rats
The diet to which both c9t11 and Se-yeast were added effectively decreased the BWG of rats and showed a tendency to lower feed conversion efficiency (FCE), whereas the diet enriched in only 2% of the CLA isomer mixture decreased feed intake as well as tended to most effectively decrease BWG
Summary
The term conjugated linoleic acid (CLA) isomers refers to a collection of positional and geometric isomers of octadecadienoic acid with conjugated double bonds. Recent investigations have shown that feeding diets enriched in high-selenized yeast (Se-yeast; 83-60% Se as Se-methionine (Se-Met) (Rayman, 2004)) to animals results in effective induction of antioxidant enzymes, indicating that the animal converts this chemical form of Se-Met to Se-Cys, which is an essential amino acid for the synthesis of this Se-protein (Schomburga et al, 2004; Whanger, 2004; Korniluk et al, 2006) These protective effects of dietary Se (as high-selenized yeast) on the deposition of CLA isomers and other fatty acids in the body of mammals may be plausible
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