Optimal Dietary Protein Requirement for Juvenile Sesarmid Crab (Episesarma singaporense).

Abstract

Simple SummaryEssential information on the major nutrients which could affect the survival and growth of early juvenile Episesarma singaporense crabs, especially their protein requirements, is still lacking. Therefore, the objective of this study was to determine the dietary protein requirement for early juvenile E. singaporense crabs. Growth performance, feed utilization, digestive enzyme activity, and muscle amino acid profiles were used as criteria for assessing the suitable treatment. Based on our investigations, desirable characteristics were achieved in the crabs fed with diet containing 45% protein. This level is similar to previous reports in other crab species, and could be employed in preparing artificial diets for this species.The optimal dietary protein requirement for sesarmid crabs (Episesarma singaporense) was investigated. Juvenile E. singaporense, individually reared in plastic glasses containing 250 mL sea water, were fed five fish meal-soybean meal-microbound diets variously containing dietary protein levels of 30%, 35%, 40%, 45% and 50% for six weeks. A completely randomized design was used in the experiment, comprising five treatments with 60 crabs in each. At the end of the experiment, a significant improvement in survival was observed in all treatments relative to the diet containing 30% dietary protein (p < 0.05) while the growth performance parameters did not differ across the five dietary groups. A significantly higher protein efficiency ratio was observed in the E. singaporense crabs receiving 45% dietary protein relative to the remaining treatments. The specific activities of the digestive enzymes, pepsin-like, trypsin, amylase, and lipase, and the amylase to trypsin ratio fluctuated across the five treatments, but that of chymotrypsin remained consistent, suggesting different nutritional responses to the various dietary protein levels. The crabs receiving the 45% protein diet had significantly higher in essential amino acid (EAA) profiles followed by the 40% protein diet, although some EAA values were only moderate. The pattern for the non-EAA (NEAA) was reversed, and the ΣEAA/ΣNEAA ratio was higher in the crabs receiving the 45% protein diets relative to the other treatments. Based on our investigations, the optimal dietary protein requirement achieving desirable characteristics of juvenile E. singaporense crabs was 45%. This finding would be a useful guideline in preparing artificial diets for the mariculture of this species.