The Early Ontogeny of Some Pancreatic and Brush Border Enzymes in the Hatchery Produced Stellate Sturgeon, Acipenser stellatus

This study aimed to determine the level of some brush border and pancreatic digestive enzymes through different stages of feeding and food shifts from hatching to 540 degree days post-hatching (ddph) in Stellate sturgeon (Acipenser stellatus). The evaluated brush border enzymes are alkaline phosphatase, aminopeptidase N, and leucine alanine peptidase, and the pancreatic ones are α-amylase, and bile salt-activated lipase. The results revealed that all these either brush border or pancreatic were present at hatching. Intercellular brush border enzymes including alkaline phosphatase and aminopeptidase N reached their highest levels at 234 and 288 ddph (2.93 ± 0.12 and 3.64 ± 0.14 U mg protein⁻¹ respectively) which were significantly different from hatching. Despite showing some fluctuations to the end, they remained high which can be suitable proof of the initiation of digestive activity in the intestine lumen. The highest specific activity of leucine alanine peptidase was observed at 234 ddph (0.15 ± 0.006 U mg protein⁻¹)and then started to decrease significantly to the end which indicates the transformation of digestion into intercellular form. Pancreatic enzymes including α-amylase and bile salt-activated lipase were high at hatching (7.39 ± 2 and 7.26 ± 0.8 U mg protein⁻¹) showing some fluctuations to the end. This high level at hatching can emphasize the necessity of the ability to consume the yolk sac composition right at hatching. The fluctuations at weaning stages can be due to the carbohydrate and lipid composition of diets.