Effect of dietary asparagine and protein-equivalents in crystalline amino acid diets on asparagine metabolism in chicks.
The effect of dietary asparagine and protein-equivalents from crystalline amino acid mixtures upon asparagine metabolism in chicks were studied. Liver and kidney asparaginase activities were significantly increased in chicks fed 44.6% protein-equivalents compared to chicks fed the Illinois chick standard amino acid mixture containing 14.8% protein-equivalents. The asparagine synthetase activity in chick liver and kidney was not significantly changed by protein-equivalents or dietary asparagine. Liver and kidney asparaginase activities in chicks fed 14.8% protein-equivalent standard diets were decreased with increasing levels of dietary asparagine (0,2 and 6%). Kidney asparaginase activities in chicks fed 44.6% protein-equivalents also were decreased with increasing levels of asparagine but liver asparaginase in these chicks was not changed with dietary asparagine. The plasma asparagine concentration was dependent on the amount of dietary asparagine and protein-equivalents. Dietary asparagine increased plasma asparagine in chicks fed 14.8 and 44.6% protein-equivalent diets but plasma asparagine in chicks fed the 14.8% protein-equivalent diet plus 6% asparagine was 3.5 times higher than plasma asparagine in chicks fed the diet containing 44.6% protein-equivalent plus 6% dietary asparagine. Plasma asparagine in chicks fed the 44.6% protein-equivalent diet with 6% asparagine was reduced due to increased asparaginase activity.