Evaluation of practical diets for the Caribbean spiny lobster Panulirus argus (Latreille, 1804): effects of protein sources on substrate metabolism and digestive proteases

The formulation of artificial diets is a fundamental issue in the development of lobster aquaculture. The impact of inclusion of clam, squid, chiton, and high-quality fish meal in a local fish meal-based diet on substrate metabolism and digestive proteases in juveniles Panulirus argus was evaluated by using two dietary protein levels, 25% and 35%, with 20% protein the basal level. The oxygen consumption/ammonia excretion ratio showed that lobsters fed clam and chiton diets used protein for oxidation at the two dietary protein levels, while lobsters fed high-quality fish meal and squid diets used protein-lipid at 25% protein. Higher protein levels led to an increase in the contribution of protein to energy metabolism. Digestive protease activity increased with squid meal in diets. Our results suggest that the inclusion of squid and high-quality fish meal in local fish meal diets increases the nutritional value of the diet for P. argus juveniles and that squid enhances digestive proteases activities in the hepatopancreas. However, grow-out trials are needed to fully demonstrate the growth-enhancing effect of these protein sources in formulated diets for juveniles P. argus and to decide whether the growth rate increase is sufficient to warrant using these protein sources.