Effect of Dietary Lipid Sources on Growth, Enzyme Activities and Immuno-hematological Parameters in Catla catla Fingerlings

Ninety advanced Catla catla fingerlings (av. wt. 16 g) were randomly distributed in six treatment groups with three replicates each for an experimental period of 60 days to study the effect of dietary lipid source on growth, enzyme activities and immuno-hematological parameters. Six isoprotein (40.0-41.9%) and isocaloric (4,260 kcal $kg^{-1}$) semi-purified diets were prepared with varying levels of soybean oil (SBO) and cod liver oil (CLO) within a total of 8% lipid viz., $D_1$ (Control), $D_2$ (8% SBO), $D_3$ (6% SBO and 2% CLO), $D_4$ (4% SBO and 4% CLO), $D_5$ (2% SBO and 6% CLO) and $D_6$ (8% CLO). Highest SGR was noted in $D_5$ (0.73${\pm}$0.03) group, which was similar with $D_3$ (0.71${\pm}$0.02) and $D_4$ (0.69${\pm}$0.01) groups. Activity of intestinal lipase, hepatic glucose-6-phosphate dehydrogenase (G6PDH) and aspartate amino transferase (AST) of the lipid treatment groups were significantly higher (p<0.05) than the control group. The respiratory burst activity of the phagocytes (Nitroblue tetrazolium (NBT)) was highest in $D_2$ (1.95${\pm}$0.21) followed by $D_3$ (1.19${\pm}$0.15) group, which were significantly (p<0.05) higher than the other groups. Globulin level was significantly higher in $D_3$ (1.29${\pm}$0.08) than in the other groups expect $D_4$. Hemoglobin content and total erythrocyte count did not show any significant difference. From this study, it is concluded that a diet containing 6% soybean oil and 2% cod liver oil ($D_3$) yields higher growth and immune response in Catla catla fingerlings and would be cost effective.