APPORTIONING LEUCINE REQUIREMENTS FOR MAINTENANCE VERSUS GROWTH FOR RATS

Purified diets containing six levels of leucine were fed to growing ra ts to evaluate the leucine requirement for maintenance and for growth. A model was employed to separate the laucine requirement for maintena nce from its requirement for growth. Based on weight, gain response, t he leucine need for growth was 13.24 mg/g live weight gain and the mai ntenance requirement was 0.40 mg per unit of metabolic body size (W-g( .75)). The plateau of blood plasma leucine concentration was reached a t 99 mg leucine intake/day. Previous leucine requirements for growth a nd for maintenance were in close agreement with these estimates.