Comparison of growth and digestive enzymes activity of kutum (Rutilus kutum) during ontogeny fed with live prey and artificial feed

The effects of two diets, live prey (Artemia nauplii) and artificial diet, were evaluated on growth performance and digestive enzymes activities of kutum (Rutilus kutum) larvae during a period of 30 days post hatching (dph). Larvae were stocked in 115-L aquariums at a density of 60 individual L-1 and fed ad libitum four times a day. According to the results, artificial feed fed group showed higher growth rate compared to Artemia nauplii fed group. However, the survival rate of larvae fed with Artemia nauplii was significantly higher than artificial diet. Pancreatic and intestinal enzymes were detected in kutum larvae before starting the first feeding. It is showing that enzyme synthesis in the early stages of development is not triggered by food ingestion but rather is genetically programmed. Fluctuations of the specific activity of pancreatic enzymes or intestinal enzymes were normally observed during larval development as a result of different metabolic and physiological events. Apart from fluctuations, the specific activity of trypsin and chymotrypsin in Artemia fed group was higher compared to artificial diet at the end of the rearing period. Artemia fed group exhibited a higher amylase value than artificial feed fed group. In the case of lipase, the same trend was recorded in larvae fed live food on 8 dph. Conversely, the specific activity of alkaline phosphates and aminopeptidase N was significantly higher in artificial feed fed group, suggesting better developmental and nutritional status in former than the latter group. We can conclude that the kutum digestive tract is well adapted to carbohydrates digestion which confirms that digestive physiology of kutum is proximate to that of omnivorous species.