EFFECT OF THE MOLECULAR-FORM OF DIETARY NITROGEN SUPPLY IN SEA BASS LARVAE - RESPONSE OF PANCREATIC-ENZYMES AND INTESTINAL PEPTIDASES

Sea bass (Dicentrarchus labrax) larvae were weaned at day 25 with micr oparticulated diets in which 10% of the nitrogen supply had different molecular forms: amino acid mixture (SLAA), casein hydrolysate (SLH) o r fish meal (SLP). The control group (LP) was fed live prey. No differ ence was observed in larval growth between the weaned groups, but the survival was significantly higher in the SLH group. Trypsin secretion was stimulated in the SLAA group, whereas the SLH diet reduced the sec retion from the exocrine pancreas. The activity of the leucine-alanine peptidase, located in the cytosol of enterocytes, remained high in al l weaned groups. However, the activity of the peptidases of the brush border membrane increased during the development phase in the control group. These results suggest that weaning with a classic compound diet delays enterocyte differentiation by maintaining the larval features of digestion. A compound diet containing protein hydrolysate can atten uate the delay of intestinal maturation.