Metabolic and digestive enzyme activity of Pangasianodon hypophthalmus (Sauvage, 1878) fingerlings in response to alternate feeding of different protein levels in the diet

A feeding trial was conducted for 90 days to assess the metabolic and digestive enzyme activity in response to alternate or mixed feeding of different protein levels in the diet of Pangasianodon hypophthalmus fingerlings. One hundred and forty four fingerlings with an average weight of 5.0-5.5 g were distributed into four experimental groups each with triplicate. Four iso-caloric diets with varying level of crude protein viz., 35%, 30%, 25% and 20% were made and designated as diet 35P, 30P, 25P and 20P respectively. Four treatments were maintained based on four different feeding schedules such as continuous feeding of diet 35P (35P/35P), alternate feeding of 1 day diet 35P next day diet 30P (35P/30P), alternate feeding of 1 day diet 35P next day diet 25P (35P/25P) and alternate feeding of 1 day diet 35P next day diet 20P (35P/20P). As a result, specific growth rate (SGR) and weight gain percentage were relatively higher in treatment (35P/25P) followed by (35P/35P) and (35P/30P). The metabolic enzymes such as lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PDH), Glucose-6-phosphatase (G6Pase), alkaline phosphatase (ALP), acid phosphatase (ACP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) were expressed better in (35P/35P) group followed by (35P/25P) and (35P/30P) groups. The digestive enzymes, protease and lipase activities were higher in (35P/35P) and (35P/25P) groups. The present study revealed that the better nutrient utilization and growth of 35P/25P group is because of their balanced digestive and metabolic enzyme activities through alternate level of higher and lower protein diet.