Protein Metabolism in Livers of Chicks Fed Deficient-to-Excess Quantities of Protein and Lysine and Infected with Tuberculosis

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Abstract
Protein metabolism was studied in individual livers of chicks conditioned from day of hatch with diets containing deficient-to-excess quantities of protein and L-lysine and infected with tuberculosis (Mycobacterium avium). Levels of total protein and the nucleic and free amino acids, used as parameters, were established and correlated with a TB involvement index based on morphological changes. Liver size increased with the intensity of the infection and with increasing dietary protein or lysine. This was attributed to an increase in protein anabolism. Cellular levels (in terms of DNA) of each of the 7 free amino acids observed decreased as liver size and the degree of infection increased, with lysine and arginine depressed to the greatest extent. The same effects were apparent when total quantities of free amino acids of the liver were calculated. Control or TB-infected chicks fed diets containing deficient or excess protein or lysine had generally lower cellular levels of free amino acids. In addition, the inoculated chicks conditioned with these same diets had a greater degree of tuberculous involvement compared with those fed diets with the normal amount of these nutrients.