Influence of dietary selenium level on the concentration of conjugated linoleic acid isomers, other fatty acids and amino acids in the liver and femoral muscles of rats

The purpose of the present study was to determine the influence of diets containing conjugated linoleic acid isomers (CLAmix) with or without low (LSe) or high (HSe) concentration of selenised yeast (SeY) on body weight gain (BWG), feed conversion efficiency (FCE), and concentrations of CLA isomers and other fatty acids (FA) in the liver and femoral muscle of rats. The investigation was performed on 48 female rats (Wistar, Hsd Brl Han: WIST), aged 8 weeks with an initial body weight of 195.7 ± 0.8 g. After one week of submaintenance feeding, for 6 weeks the rats were fed ad libitum the Labofeed H diet supplemented with 1.5% CLAmix with or without low (0.2 μg Se/g diet) or high (0.5 μg Se/g diet) concentration of Se as SeY. The diet enriched with LSe or HSe elevated the BWG of rats compared with the control group, while the LSe diet resulted in the most efficient increase in BWG. The diet containing CLAmix, irrespective of the presence of SeY, stimulated the accumulation of Se in the liver and muscles in comparison with the diet enriched with SeY. The addition of SeY to the diet enriched with CLAmix stimulated the accumulation of cis9trans11 (c9t11), t10c12 and cc isomers of CLA in the liver. The diet containing CLAmix and LSe most efficiently increased the concentration of these CLA isomers in muscles. The diets enriched with SeY increased the concentration of essential, endogenous and total amino acids (AA) in the liver, whereas the diets enriched with SeY or CLAmix reduced the concentration of these AA in muscles. The diets enriched with CLAmix and/or SeY decreased the Δ9-desaturase index in the liver and muscles compared with the control group. These diets increased Δ4-, Δ5- and Δ6-desaturase indexes in muscles, but significantly reduced the elongase index compared with the control group. Our study shows that dietary CLAmix increased the concentration of C14:0, C18:0 and the sum of saturated FA (SFA) in the liver, whereas the diets enriched with SeY, irrespective of the presence of CLAmix, slightly reduced the concentration of C14:0, C18:0, and SFA in muscles compared with the control group. The diets containing SeY and/or CLAmix increased the accumulation of arachidonic acid (ArA), linolenic acid (αLNA) and c4c7c10c13c16c19C22:6 in the liver compared with the control rats. Negative effects of dietary SeY and/or CLAmix on the accumulation of αLNA, c5c8c11c14c17C20:5, c7c10c13c16c19C22:5, c4c7c10c13c16c19C22:6, linoleic acid, ArA and c8c11c14C20:3 in muscles were found out. The CLAmix diet increased the Δ4-, Δ5-desaturase and elongase indexes in the liver. It also increased the Δ4-, Δ5- and Δ6-desaturase indexes in muscles, but significantly reduced the elongase index compared with the control group. The finding that the diet with CLAmix and HSe fed to rats decreased total FA and most efficiently increased the content of Se and essential AA in muscles is valuable information for nutritionists carrying out research on farm animals to improve the nutritive value of food from the aspect of human health.