Effect of starvation on free histidine and amino acids in white muscle of milkfish Chanos chanos.

Milkfish (Chanos chanos) decreased their body weight from 47 to 28 g over the 60-day period of starvation. Starvation also resulted in the reduction of muscle lipid and protein, and hepatosomatic index. The predominant free amino acid (FAA) in white muscle of milkfish was histidine, followed by taurine and glycine. In the first 25 days of starvation, no significant change in histidine was found. After 40 days of starvation, however, the histidine concentration was significantly decreased by 46%, and remained unchanged thereafter. As compared to control group fish, the 60-day-starved fish possessed only half the amount of histidine. Taurine and glycine, on the other hand, showed no significant changes throughout starvation. Taurine became the most predominant in the FAA pool after 40 days of starvation, and the concentration of 60-day-starved fish was two times higher than that of control group fish without starvation. The ratios of histidine, taurine, and glycine to total FAAs remained approximately the same although the individual contributions varied considerably to the total FAAs during starvation. The results of this study suggested that a good strategy would be to keep taurine and glycine in milkfish muscle at relatively high levels for physiological function as histidine decreased drastically for energy source under conditions of food deprivation.