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A 60-day indoor experiment was conducted to study the effect of dietary supplementation of biofloc on metabolic enzyme activities and immune responses in Penaeus monodon juveniles. Biofloc developed in indoor fibreglass-reinforced plastic ( FRP) tanks (1000 L) was used as dietary supplement in P. monodon (2.90 ± 0.10 g) reared in 1000-L FRP tanks. Graded level of dried biofloc was included in shrimp basal diets, 0% (control, B0), 4% (B4), 8% (B8) and 12% (B12). The level of metabolic enzymes like malate dehydrogenase ( MDH), aspartate aminotransferase ( AST) and alanine aminotransferase ( ALT) was not significantly different with control up to 8% dietary supplementation. A higher level of total haemocyte count ( THC) was noticed in B8 (22.16 ± 2.17 × 106 cells mL−1) and B4 (21.11 ± 0.56 × 106 cells mL−1) compared with control, C (14.61 ± 2.74 × 106 cells mL−1). Biofloc-supplemented groups recorded significantly higher ( P < 0.05) serum SOD and catalase activity ( P < 0.01) in comparison with control. The groups fed with 4% dietary biofloc supplement recorded highest relative percentage survival ( RPS), 45% after challenge with Vibrio harveyi followed by 36% and 27% RPS in B8 and B12 groups. Based on these results, it can be concluded that supplementation of biofloc even at 4% level in the feed improves immune responses and metabolic activities in black tiger shrimp juveniles. [ABSTRACT FROM AUTHOR]

A 60-day indoor trial was conducted to study the effect of periphyton supplementation on metabolic and immune responses in tiger shrimp, Penaeus monodon. Periphyton developed over bamboo substrate in outdoor tanks (15 m2) was used as dietary supplement for P. monodon (2.02 ± 0.04 g) reared in 1000 L FRP tanks. Graded levels of periphyton were included in shrimp basal diets: 0% (P0), 3% (P3), 6% (P6), 9% (P9) and P0 diet with natural periphyton ( NP) over bamboo substrate. At the end of the trial, P6 and NP showed significantly higher ( P < 0.01) growth rate, 23.9% and 20%, respectively, compared with control, P0. Comparatively, lower level of metabolic enzymes, such as lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and alanine aminotransferase, was recorded in treatments P3, P6 and NP compared with control, P0. The periphyton-supplemented group, P3 had significantly higher ( P < 0.05) superoxide dismutase (15.83 ± 0.96) and catalase activity (15.73 ± 0.69) compared to 6.88 ± 2.84 and 9.15 ± 0.67 unit mg−1 protein min−1, respectively, in P0. Similarly, higher total haemocyte counts, 32.58 ± 1.30, 28.51 ± 3.12 and 27.26 ± 4.43 × 106 cells mL−1, were recorded in P6, NP and P3, respectively, compared to P0, 23.57 ± 1.80 × 106 cells mL−1. After challenge with Vibrio harveyi, P3 recorded the highest relative percentage survival 67% followed by NP (58%) and P6 (42%) compared with control. However, treatment with highest periphyton inclusion (P9) did not differ significantly with P0 on growth and immunological parameters. This study indicates that periphyton supplementation at 3-6% level improves growth, immune response and metabolic activities in P. monodon. [ABSTRACT FROM AUTHOR]

The effect of various dietary starch to proteins ratios ( STA/P) on growth performance, oxidative status and liver enzyme activities involved in intermediary metabolism in juvenile Nile tilapia was evaluated. Four isocaloric-practical diets (12.73 MJ kg−1 digestible energy) with increasing STA/ CP ratios were formulated. These were designated D0 (344 g crude protein ( CP) and 163.5 g starch ( STA) kg−1), D1 (310 g CP and 243 g STA kg−1), D2 (258 g CP and 322 g STA kg−1) and D3 (214 g CP and 401 g STA kg−1). Each diet was fed to triplicate groups of 60 fish (2.7 g) for 45 days. Compared with the control diet (D0), significantly ( P < 0.05) depressed growth and feed efficiency were observed only in the groups fed on diet D3. The activities of hepatic enzymes involved in glycolysis and lipogenesis pathways were significantly enhanced in groups fed on diet D3 compared with other diets. A significant ( P < 0.05) increase in catalase activity was detected only in groups fed on diet D3. Similarly, a significant ( P < 0.05) enhancement in superoxyde dismutase, glutathione S-transferases and glutathione peroxidise was observed in groups fed on diets D2 and D3 compared with other diets. Results demonstrate the ability of juvenile Nile tilapia to spare protein by dietary carbohydrate. [ABSTRACT FROM AUTHOR]