Variation in the biochemical composition of Penaeus monodon tissues during the reproductive cycle.

Abstract

The gonadosomatic index (GSI) and the hepatosomatic index (HSI) were determined for wild-caught, eyestalk ablated Penaeus monodon at 5 reproductive stages (I to V). Tissues of the muscle, ovary and hepatopancreas in each stage were analyzed for crude protein and amino acid composition.

Results showed that the GSI increased from stage I (immature) to IV (fully mature) but declined at stage V (spent) while the HSI did not change significantly (P less than or equal to 0.05). Muscle protein content did not vary markedly from stage I to V except for a slight lowering at stage III (late maturing). Ovarian protein increased from stage I to IV and decreased at stage V while from stage II, the reverse was true for hepatopancreas.

Generally, few significant differences in amino acid content were found. Glutamic acid content significantly differed among stages in all three tissues. In addition, phenylalanine in the muscle, histidine and lysine in the ovary and arginine and luecine in the hepatopancreas differed among stages. The muscle had slightly higher arginine and gluatmic acid contents than the ovary and hepatopancreas but was lower in threonine and valine. The ovary had the lowest glycine content.

Results showed similar amino acid levels among tissues and maturation stages, suggesting that amino acids are fixed and not affected by much variation.