Retention efficiency and release of nutrients in the digestive tract of larval shrimp (Penaeus japonicus Bate) using different microencapsulated diets

Abstract

Retention efficiency and release of the nutrients in the digestive tract of larval shrimp (Penaeus japonicus) using the diets microencapsulated with gelatin and ethyl cellulose respectively were evaluated. The microencapsulated diets were produced using the fluidized bed coating process. 7.8 % gelatin and 4.2 % ethyl cellulose to the whole microencapsulated diet were respectively adopted as coating material. After immersion in 35 ‰ NaCl solution for 1 h, the nitrogen retention efficiency was significantly lower in the diet microencapsulated with gelatin compared with the diet microencapsulated with ethyl cellulose. Free amino acid retention efficiency of the diet microencapsulated with gelatin and ethyl cellulose was 12.9, 17.2 %, respectively. The mysis II larval shrimp (P. japonicus) 10 days after hatch were fed two different microencapsulated diets for 20 days and grew significantly more than the control larval shrimp fed with Artemia and shrimp flake. The nutrient components in intermediate intestine of larval shrimp were increased gradually in the order of the control (50 % shrimp flake + 50 % Artemia), Group I (50 % diet microencapsulated with gelatin + 25 % shrimp flake +25 % Artemia), Group II (100 % diet microencapsulated with gelatin), and Group III (100 % diet microencapsulated with ethyl cellulose). This study confirmed that the microencapsulated diets with slow and controlled release characteristic in the digestive tract of the larval shrimp (P. japonicus).