Ontogenetic changes of pancreatic enzymes and fatty acids in egg and larvae of grass carp (Ctenopharyngodon idella)

Ontogenetic changes of digestive enzymes (pancreatic) and fatty acids profile in fertilized grass carp (Ctenopharyngodon idella) eggs and eleuthero-embryo were examined at the beginning of exogenous feeding. The fertilized egg، newly hatched larvae، one-day-old larvae، larvae in 2/3 yolk-sac absorption stage and complete yolk-sac absorption stage were sampled. Then، the digestive enzymes including trypsin، chymotrypsin، lipase and amylase which related to the digestion of protein، lipid and carbohydrate were measured in egg، at hatching stage and onset of exogenous feeding. High specific activity of trypsin and chymotrypsin in egg and newly hatched larvae revealed their importance during embryogenesis and hatching (P<0. 05). The results showed the increasing trend in the specific activity of lipase and amylase (P<0. 05). The results also showed that the increase in saturated fatty acids (SFA) coincide with a decrease in monounsaturated fatty acids (MUFA)، indicating the role of monounsaturated fatty acids for energy provision during embryogenesis and larval development.