GROWTH IS COMPROMISED IN RATS FED OZONE-TREATED CASEIN

Modified casein containing few phenylalanine residues and no other aro matic amino acid residues was obtained by ozonolysis of casein. Althou gh 68% of phenylalanine was decomposed by ozonolysis of casein, ozonol ysis caused alterations beyond the destruction of aromatic amino acid residues. Nearly the same degree of decomposition of amino acid residu es was observed in casein ozonated after predigestion by pepsin. Rats were fed diets containing 8% casein supplemented with methionine and a spartic acid (BC-AA), 8% ozonated casein supplemented with methionine and free amino acids lost by ozonolysis (8C-AA), 8% casein ozonated af ter predigestion by pepsin supplemented with methionine and free amino acids lost during preparation (8POC-AA) or 7.6% amino acid mixture. T he growth of rats fed the BOC-AA diet was significantly lower than tha t of those fed 8C-AA or 7.6AA diets. The growth of rats fed the 8POC-A A diet was comparable to growth of those fed 8OC-AA. The biological va lues of the 8OC-AA and 8POC-AA were comparable to that of 8C-AA, but t rue digestibility of 8OC-AA was significantly lower than that of 8C-AA . True digestibility 8POC-AA was significantly improved relative to 8O C-AA, but the growth of rats fed 8POC-AA was not improved relative to that of those fed 8OC-AA. Kidney and cecum weights of rats fed 8OC-AA and 8POC-AA were significantly heavier than those of the 8C-AA-fed gro up, although histopathological examination of kidneys showed no deteri oration compared to that of the 8C-AA-fed group. Consequently, ozonoly sis caused changes in casein that extended beyond the decomposition of aromatic amino acid residues, and the growth of rats fed ozonated cas ein supplemented with methionine and free amino acids lost by ozonolys is was significantly lower than that of those fed casein supplemented with methionine and aspartic acid.