ADAPTATION OF DIGESTIVE ENZYMES TO DIETARY-PROTEIN, CARBOHYDRATE AND FIBER LEVELS AND INFLUENCE OF PROTEIN AND CARBOHYDRATE QUALITY IN PENAEUS-VANNAMEI LARVAE (CRUSTACEA, DECAPODA)

Activity of digestive enzymes (trypsin, chymotrypsin and amylase) was studied in relation with food in Penaeus vannamei larvae first stages. Microparticles containing casein involved the decrease of soluble pro tein content and enzyme activities. Specific trypsin activity but not chymotrypsin was correlated (p < 1 %) to casein level between 10 and 6 0 % in microparticles. Cellulose fibres in food seemed to have little effect on digestive enzymes. Starch, between 1 and 20 % in micropartic les, had no influence on specific amylase activity. The effect of diff erent feeding conditions were also tested on growth. No clear relation ship between growth and enzyme is established since only trypsin is co ncerned in the case of a casein dose effect in the food. The protein s ource (casein, gelatin, squid meal or fish protein soluble concentrate ) as well as the carbohydrate quality (soluble starch, standard com st arch, amylopectin com starch or pregelatinized com starch) were tested . Squid meal stimulated significantly chymotrypsin activity (p < 2 %) while trypsin activity decreased with fish protein soluble concentrate (p < 5 %). Source of carbohydrate seemed very important, amylase acti vity increased significantly (p < 2 %) with com starch. These adaptati ons are not correlated to growth performances since squid meal or fish protein soluble concentrate improved larval development until zoe 3 s ubstage. These results suggest a specific induction of digestive enzym es to the food quality in larvae independent of growth performances.