title: Comparative utilization of the isomers of phenylalanine and phenyllactic acid by chicks and rats.
abstract: A series of experiments was conducted to assess quantitatively the growth-promoting capacity of the isomers of phenylalanine (Phe) and phenyllactic acid (PLA). The slope-ratio procedure was used to determine percent efficacy relative to l-Phe. Addition of the isomers of Phe to a Phe-deficient chemically-defined diet produced linear growth and feed efficiency responses. Only the l-isomer and racemic mixture of PLA elicited a gain or gain:feed response. Efficacy estimates for male chicks were: dl-Phe, 90.1%; d-Phe, 74.6%; l-PLA, 70.1%; dl-PLA, 5.9%. The comparative utilization of d-Phe, phenypyruvic acid (PPA) and l-PLA by chicks was also evaluated when these compounds were fed to male chicks as the sole source of dietary Phe. PPA activity, 84.8%, was slightly greater than that of either d-Phe, 75.3%, or l-PLA, 67.4%. Efficacies of l-PLA and dl-PLA were 46.1 and 28.0%, respectively, d-PLA had no growth-promoting activity for the rat.
mesh_terms: D000818:Animals; D001682:Biological Availability; D001835:Body Weight; D002645:Chickens; D005260:Female; D005526:Food, Formulated; D007536:Isomerism; D007773:Lactates / Q000378:metabolism*; D008297:Male; D010649:Phenylalanine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors
chemical_list: D007773:Lactates; C017648:3-phenyllactic acid; D010649:Phenylalanine