Nutritional effects on body composition, energy content and trypsin activity of Penaeus japonicus during early postlarval development

Abstract

The growth, elemental (C, N, H) and biochemical (lipid, protein) composition, energy content and trypsin activity of Penaeus japonicus early postlarvae (PL1–PL20, as days after metamorphosis) fed under a commercial hatchery regime were measured. From PL1 to PL4, freshly hatched Artemia nauplii were used, followed by enriched Artemia nauplii (PL5–PL9), and a prepared diet from PL10 to PL20. Survival for the total experimental period was 80% and daily gain in absolute values of dry weight, energy and elemental composition was observed. Significant increment (P<0.05) of relative values of carbon, hydrogen and energy was verified from PL1 to PL3 as well as increases in protein and lipid content from PL1 to PL5. In the period PL10–PL20, carbon, hydrogen and energy content decreased significantly (P<0.05). This may have been due to the poor quality of diet supplied after PL5, which possibly caused malnutrition. During this period, lipid was a major source of energy for the postlarvae. Body protein of postlarvae as determined by nitrogen content (N×6.25) was overestimated after PL5, which indicates to a possible role of the non-protein nitrogen fraction under poor feeding conditions. Protein-specific trypsin activity showed significant increment (P<0.05) at periods PL1–PL5 and PL15–PL20, which may indicate a possible influence of diet composition. It is concluded that this type of approach may be useful as a tool to assess the nutritional condition of cultivated shrimp, during postlarval stages.