Regulation of free glutamate content in meat by dietary lysine in broilers

Regulation of taste is important for improving meat quality and glutamate (Glu) is one of the important taste-active components in meat. Here, the effects of dietary lysine (Lys) content on taste-active components in meat, especially free Glu, were investigated. Fourteen-day-old broiler chicks (Gallus gallus) were fed on diets containing 100% or 150% of the recommended Lys content for 10 days. Concentrations of free amino acids in plasma, muscle and liver were measured. The levels of messenger RNAs (mRNAs) for enzymes related to Glu metabolism were determined in muscle and liver. The concentration of muscle metabolites was also determined. The free Glu content in muscle of chicks fed the Lys150% diet was increased by 44.0% compared with that in chicks fed the Lys100% diet (P<0.01). The mRNA level of lysine α-ketoglutarate reductase, which is involved in Lys degradation and Glu production, was significantly increased (P