Physio-metabolic and haematological changes in striped catfish, Pangasianodon hypophthalmus fed with graded level of protein

PHYSIOLOGICAL RESPONSES OF PANGAS WITH VARIED PROTEIN

Abstract

Six isocaloric-purified diets (472.46 kcal gross energy 100 g-1 diet) were prepared as DP20, DP25, DP30, DP35, DP40, and DP45 with graded level of protein like 20, 25, 30, 35, 40, and 45 g 100 g-1 diet, respectively and fed to striped catfish, Pangasianodon hypophthalmus. for 60 days to satiation level. Maximum RNA content and RNA: DNA ratio were observed in DP40 group (P<0.05), while DNA contents did not differ significantly (P>0.05) among the groups. Maximum hepatic alanine aminotransferase (ALT) activity was recorded in DP35 and DP40 groups (P<0.05), whereas serum ALT activity followed a reverse trend with the dietary protein. Highest activities of lactate dehydrogenase and malate dehydrogenase were observed in DP20 group (P<0.05) and minimum activities in DP35 and DP40 groups. Serum glucose, and glycogen contents in liver and muscle were significantly decreased with dietary protein levels (P<0.05). Hepatic superoxide dismutase and catalase activities were lowered with dietary protein levels(P<0.05). Serum albumin-globulin ratio and total erythrocytes count were increased with the dietary protein levels (P<0.05). While haemoglobin content exhibited a positive correlation (r= 0.75) with the dietary protein levels (P<0.05). Hence, from the result it can be concluded that some key enzymes like hepatic ALT, LDH, MDH, SOD and catalase enzymes clearly response with respect to the dietary protein level, which can be used to determine the dietary protein requirement, which also match with the growth response in terms of RNA: DNA. Based on these parameters it can be concluded that minimum protein required to support the best growth in striped catfish, P. hypophthalmus ranged between 35 and 40 g protein 100 g-1 diet.