Assessment of digestive enzymes activity during the fry development of Rainbow Trout, Oncorhynchus mykiss: from hatching to primary stages after yolk sac absorption

 The aim of this study was to determine the activity of digestive enzymes during the fry development of Rainbow trout ( Oncorhynchus mykiss ), which has a remarkable role in food digestion and absorption in the first feeding. The assessment of digestive enzymes activity of gastric (pepsin), pancreatic (trypsin, chymotrypsin, α-amylase and lipase) and intestinal (alkaline phosphatase) revealed that enzymes were available on the first day after hatching (DAH) but their activity showed no significant difference from hatching to day ۱۲ (P > ۰.۰۵). An increased activity was seen between ۱۲ and ۱۸ DAH and this activity was significantly higher than the first ۱۲ days (P < ۰.۰۵). In the primary stages after yolk sac absorption (after ۲۰ to ۳۱ days), enzymes activity showed an increased profile however none of them showed a significant difference between ۲۰ to ۳۱ DAH (P > ۰.۰۵). These results could be used as a basis for formulating a suitable feeding and also selecting the best time for starting the feeding so that optimum nutritional values and cost-effectiveness are achieved.

Keywords:

Digestive enzymes , Fry development , Rainbow trout