Abstract
The effects of lysine and threonine added to the rice diet on the growth, liver lipid content and plasma free amino acid levels were studied in young (5-weeks-old) and adult (15-weeks-old) rats.
Body weight gain and feed efficiency were improved in young rats fed a rice diet containing lysine and 6.3% or 12.0% protein. Adult rats fed a 89% rice diet supplemented with lysine showed an increase in the body weight gain and feed efficiency. Addition of lysine and threonine to a 89% rice diet improved the body weight gain in young rats, but there was no improvement in adult ones. The liver lipid content of young rats fed a 89% rice diet was 11.0 to 13.5% (dry weight). The content of liver triglyceride was increased with lysine supplementation in young rats fed a 89% rice diet, but the addition of threonine to the diet cancelled the high accumulation of triglyceride. No significant differences in the content of liver triglyceride were observed among adult rats fed the various experimental diets. Free threonine levels of the plasma and liver were lowered in young rats fed a 89% rice diet supplemented with lysine. The fatty acid composition of liver triglyceride of young or adult rats fed a 89% rice diet was not affected by the supplement of amino acids.
