FURTHER STUDIES ON URINARY 3-METHYLHISTIDINE EXCRETION AS AN INDIRECT INDEX OF DIETARY AMINO ACID ADEQUACY IN RATS
DOI :
https://doi.org/10.51791/njap.v10i.2716Résumé
As a further step in the determination of the sensitivity of urinary 3-methylhistidine (3-MeH) to essential amino acid adequacy in diet, 36 male albino rats of the Wistar strain were divided into six groups +of six rats per group. Each group with an initial .mean live weight of 106.52 ± 0.54g was fed in individual metabolic cages on a basal diet supplemented with graded levels of DL-methionine. Total methionine in diet ranged between 0.25 and 1.05%. The study lasted 10 days. The response of urinary 3-methylhistidine excretion to the graded levels of methionine in diet was compared to responses obtained from growth performance characteristics, plasma urea concentration, liver nitrogen and creatinine excretion. With the exception of feed intake, all other indices of dietary protein adequcy and efficient amino acid utilization viz growth rate, protein efficiency ratio, serum urea concentration, and creatinine excretion were significantly (P 0.05) to P 0.01) influenced by dietary methionine level. Maximum growth rate, liver N and urinary 3-methylhistidine were observed. in rats given 0.45% total methionine in diet. Supplementing the basal diet to contain 0.45% total,' methonine significantly (P 0.01) decreased serum urea concentration. Urinary 3-methylhistidlne excretion was found by regression analysis to be positively correlated to body weight gain (r = 0.73), feed intake (r = 0.61), urinary creatinine excretion (r = 0.74) and liver N (0.72) but negatively correlated to dietary methionine level (r = —0.41). We suggested that urinary 3-MeH excretion be added to the list of available indicts for dietary amino acid adequacy.
