Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 1 B54-B57, Copyright © 1995 by The Gerontological Society of America
Maintenance requirements for dietary protein in 11- and 18-month-old male rats
LK Linley, K Reynolds, M Lentner and SJ Ritchey
Department of Human Nutrition and Foods, Virginia Polytechnic Institute and State University, Blacksburg.
Body weight, lean body mass (total weight less body fat), carcass protein,
and serum protein were examined as potential parameters by which to assess
the effect of age on protein requirements for maintenance in male rats,
aged 11 months and 18 months, fed diets containing 1.53, 3.41, 4.98, 6.52,
or 8.05% dietary protein, casein plus methionine, for a 5-week period. Body
weight change was maintained in older animals at 6.52% dietary protein and
in younger animals at 4.98% dietary protein. Older animals consuming the
two diets highest in protein had a greater percent body fat and less
percent body protein than younger animals. Significant effects of diet and
the interaction of diet and age on serum protein were also observed. As
dietary protein level increased, serum protein increased gradually in
younger rats, but only between 3.41 and 4.98% dietary protein in older
rats. Lean body mass and total carcass protein increased as dietary protein
level increased, but there were no significant differences due to age or
the interaction of diet and age. Changes in body weight indicate a greater
protein requirement for 18-month-old rats compared with 11-month-old rats,
although complicated by greater food intake and fat deposits in older
animals. Measures of body protein indicate that age has some influence on
protein needs for maintenance purposes.
