Effect of excess dietary methionine on weight gain and plasma amino acids in kittens.
Four groups of five kittens each were individually fed for 6 wk either a purified control diet containing 0.5% methionine (Met) (based on 18% casein supplemented with arginine, cystine and threonine) or one of three experimental diets containing an additional 2, 3 or 4% L-Met. The diets with added Met caused a reduction in food intake (FI) on the second day and a negative body weight gain (BWG), in proportion to the level of added Met. After 10 d, kittens fed the 2 and 3% Met diets increased their FI and had positive BWG. During the last 10 d of the experiment, the control, 2% Met and 3% Met groups had BWG of 28, 15 and 0 g/d, respectively. Kittens given the 4% Met diet showed no adaptation and continued to lose weight. In these kittens plasma concentration of Met was 50-70 times and cystathionine about three times greater than in control kittens. Four male kittens were fed the same 4% Met diet for 6 wk and then switched to a diet containing 4% L-Met plus 4% glycine (Gly) for 12 d. Average daily FI was 21.4 +/- 1.3 g with 4% Met and 48.5 +/- 2.5 g after the addition of Gly, and BWG went from negative to positive. These results indicate that growing kittens are more sensitive than rats to excess Met and have a limited adaptive capacity. Kittens did not grow normally when the diet contained 2% or more dietary Met, which was equivalent to 0.6 g Met/(kg body wt.d).
Fau
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D
Department of Physiological Science, University of California, Davis 95616.
Smalley
K A
KA
Morris
J G
JG
Rogers
Q R
QR
D000596:Amino Acids / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002415:Cats; D003540:Cystathionine / Q000097:blood; D004032:Diet; D004435:Eating / Q000187:drug effects; D005998:Glycine / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*
D000596:Amino Acids; D003540:Cystathionine; D008715:Methionine; D005998:Glycine