DE-NOVO SYNTHESIS OF HOMOARGININE IN CHICKENS IS INFLUENCED BY DIETARY CONCENTRATIONS OF LYSINE AND ARGININE

The influence of different dietary ratios of lysine and arginine on de novo synthesis of homoarginine in chickens was investigated in this s tudy. No homoarginine was detected in the diets, but was found in the plasma of birds confirming that homoarginine is synthesised de novo in chickens. Increasing dietary arginine levers increased plasma arginin e and decreased plasma homoarginine, indicating possible inhibition of homoarginine synthesis. Increasing dietary lysine levels, on the othe r hand, decreased plasma arginine, but had no consistent effect on pla sma homoarginine. When dietary lysine concentrations were low compared to arginine, homoarginine synthesis was observed to be lower. The de novo synthesis of homoarginine reflected, to some extent, the relative concentrations of lysine and arginine in the plasma. The relationship between plasma lysine/arginine ratios and plasma concentrations of ho moarginine appears to be biphasic. High correlations (r=0.82) were not ed at ratios lower than 4.5, whereas homoarginine concentrations were unaffected (r=0.19) when the ratios were above 4.5. Copyright (C) 1996 Elsevier Science Inc.