Effects of Tocols and β-Glucan on Serum Lipid Parameters in Chickens*

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Cereal grain diets affect serum lipids by their soluble fibre and tocotrienols. Chickens were fed diets containing an oat bran fraction or waxy hulless barley that were enriched or depleted in β-glucan and/or tocotrienols. Serum cholesterol and triacylglycerides and enzymes of cholesterol metabolism were measured. Weight gains appeared to be lower in birds on oat bran fraction-containing diets and higher in those on barley-containing diets supplemented with β-glucanase. All diets containing oat bran fraction or barley lowered serum total cholesterol and low-density-lipoprotein (LDL) cholesterol relative to the corn control diet. LDL cholesterol was reduced more by oat bran fraction supplemented with tocotrienols than by either oat bran fraction or tocotrienols alone. LDL cholesterol levels were the same for all barley-based diets. Activities of β-hydroxy-β-methylglutaryl coenzyme A (HMG CoA) reductase and cholesterol 7α-hydroxylase were inversely affected by the diets. Oat bran fraction plus tocotrienols, barley and solvent-extracted barley decreased HMG CoA reductase by 50% and increased cholesterol 7α-hydroxylase by 100%; other diets caused lesser effects. It was concluded that both β-glucan and tocotrienols affected cholesterol levels and metabolism, and the effects were additive or less. Removal of β-glucan from barley diets abolished or diminished effects on enzyme activities but did not alter effects on cholesterol levels, indicating the possibility of another component in barley that affected cholesterol levels.