Choline-Methionine Interrelationship in Feline Nutrition

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Abstract
Four experiments were conducted to determine both the choline requirement and the choline-sparing capacity of methionine for young cats. In the first study turkey fat, a major component of the feline choline-free purified diet, was found to contribute no bioavailable choline activity as determined by chick bioassay, thus assuring that the purified diet was, indeed, choline-free. With dietary methionine present at its minimal physiological requirement, gain and gain to feed ratio increased linearly and liver lipid decreased as dietary choline was increased from 0 to .05% to .10%. In a subsequent study, choline levels of .1% and .3% were evaluated. Maximum growth occurred at .1%, but .3% was required to achieve a lower concentration of liver lipid. A level of methionine (.37%) isomethyl to .1% choline was found capable of completely replacing the dietary need for choline. Dietary inclusion of 2-amino-2-methyl-l-propanol, an inhibitor of choline biosynthesis, increased liver lipid and decreased growth and also negated the choline-sparing activity of methionine. Thus, the primary explanation for the choline-sparing activity of methionine in the feline animal appears to lie in its function in providing methyl groups for endogenous choline biosynthesis rather than in its capacity to replace choline per se. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.