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EFFECT IN RATS OF PARTIAL REPLACEMENT OF COW'S MILK PROTEIN BY SUPPLEMENTARY NITROGEN
Author(s) -
YOUNG VER R.,
VILLARREAL ABEL
Publication year - 1970
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1970.tb12130.x
Subject(s) - weanling , amino acid , nitrogen , chemistry , glycine , excretion , tryptophan , sulfur , food science , zoology , biochemistry , endocrinology , biology , organic chemistry
SUMMARY: A number of experiments studied growth of weanling rats and urinary nitrogen excretion in young adult rats when cow's milk protein was partially replaced by varying levels supplementary nitrogen. A mixture of nonessential L‐amino acids (NEAA) or a mixture of diammoniumcitrate and glycine (DAC‐Gly) was used as the source of nitrogen. Substitution of the 15% milk protein diet to the extent of 10% slightly reduced growth; significant growth reduction occurred with substitutions of 20% and greater. Fortification of the diets containing 10.5% milk protein and the supplementary nitrogen sources with sulfur amino acids did not restore growth the maximum rate obtained with the 15% milk protein diet. Additional supplementation with tryptophan further improved growth slightly but not to the maximum rate. Several other essential amino acids, alone or in combination, had no apparent effect. Based on urinary nitrogen excretion, comparable results were obtained with young adult rats by substituting nitrogen for milk protein the diets. The reduced performance following substitution of milk protein with supplementary nitrogen may be due partly to decreased utilization of sulfur amino acids and possibly to decreased utilization of all essential amino acids.