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We evaluated the effects of dietary vitamin E on growth, immunity and regulation of the hepatopancreas in male oriental river prawn, Macrobrachium nipponense. Shrimps were fed 0, 40, 80, 160, 320 or 640 mg vitamin E/kg for 60 days. The 80 mg/kg group had the highest weight gain rate, specific growth rate and lowest feed conversion rate while there were no significant differences in survival rate and hepatosomatic index. The highest crude fat and lowest crude protein content were observed in the 160 mg/kg group. In the hepatopancreas, lysozyme, acid phosphatase and alkaline phosphatase activities were highest in the 160 mg/kg group, while superoxide dismutase, catalase and glutathione peroxidase activities decreased with increasing vitamin E levels. Malondialdehyde content initially decreased then increased with vitamin E levels, whereas the reverse was seen with total antioxidant capacity. Linoleic acid, DPA, DHA, total n‐3 polyunsaturated fatty acid and total polyunsaturated fatty acid first increased then decreased, while EPA and total saturated fatty acid rose with vitamin E levels. Total n‐6 polyunsaturated fatty acid content declined while there were no significant differences in linolenic and total monounsaturated fatty acid content. Following a toxicity test with Aeromonas hydrophila, hepatopancreas ultrastructure revealed that appropriate vitamin E levels promote an increase in mitochondria, endoplasmic reticulum and Golgi bodies, but excess vitamin E can damage cell structure. These results provide evidence that 80–160 mg/kg dietary vitamin E has a positive impact on growth, immunity and regulation of the hepatopancreas in male shrimp. [ABSTRACT FROM AUTHOR]

In this paper, the glucose tolerance tests (GTT) were performed to evaluate the effects of three dietary carbohydrate levels on growth, plasma glucose, hormones (insulin and IGF‐I), glucose homeostasis and GLUT4 gene expression of Tilapia nilotica. Juvenile tilapia (av. wt.10 g) were randomly distributed into three groups with three replicates and fed for 8 weeks with three dietary carbohydrate levels: 40% (CH), 30% (CM) and 20% (CL). After 8 weeks of feeding trial, fish were injected with glucose (30 mg/100 g body weight) for GTT. The growth performance results showed the survival rate in the CH group was significantly lower than the other two groups (p < 0.05). The GTT results showed that the plasma glucose level positively correlates with the diets' carbohydrate level initially, peaked at 1 hr and declined thereafter. The plasma IGF‐1 levels were positively correlated with diets' carbohydrate levels; first the levels increase and then decrease after injection in all the three groups. There was a direct relationship between the carbohydrate levels and the activities of liver pyruvate kinase (PK) and glucokinase (GK) enzymes. Muscle GLUT4 expression in groups changed slightly in 0–3 hr and then increased sharply during 6–12 hr. Results of this study indicated that the moderate dietary carbohydrate level may improve the glucose tolerance of T. nilotica. The carbohydrate levels can affect plasma glucose, IGF‐1 and GLUT4 expression in T. nilotica. In addition, the IGF‐1 may play a more important role on the glucose metabolism than insulin. The delayed gene transcription of GLUT4 may be one of the reasons for glucose intolerance in T. nilotica. [ABSTRACT FROM AUTHOR]

Unlike the case of mammals, teleost fish generally have poor ability to utilize carbohydrate, and the clearance of glucose from the plasma is sluggish. In this study, after a 8‐week feeding trial, we conducted a glucose tolerance test to hypothesize that the capability of grass carp (Ctenopharyngodon idellus) to clear a glucose load is associated with its nutrient history of different carbohydrate‐to‐lipid ratio diets (CHO:L: 1.52%, 5.84% and 34.84%) through glycogen synthesis and glucose metabolic key enzymes. Our results showed that after a glucose load, the plasma glucose of fish fed with high CHO:L‐ratio diet (34.84%) first declined to baseline conditions, and the peak value of liver and muscle glycogen content was significantly higher in high CHO:L‐ratio but lower in low CHO:L group (1.52%). In addition, after glucose administration, hepatic GK (glucokinase) activity of fish fed with high CHO:L‐ratio diet increased more significantly than that of the other groups, and PEPCK (phosphoenolpyruvate carboxykinase) activity obviously decreased in low CHO:L‐ratio group. The results indicated that a long‐term adaptation to the high CHO:L‐ratio diet can improved the glucose tolerance of C. idellus through the promotion of glycogen synthesis and GK activity. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of dietary inclusion of different levels of fermented macroalga, Enteromorpha prolifera, on the growth performance, digestive enzyme activities and serum non-specific immunity of red tilapia ( Oreochromis mossambicus × Oreochromis niloticus). Fish were fed the control diet or the five diets supplemented with fermented E. prolifera for 7 weeks (diets 1-5 containing 10, 20, 30, 40 and 50 g kg−1 of fermented E. prolifera respectively). The results showed that the percentage weight gain and specific growth rate ( SGR) improved significantly in fish fed diets 3, 4 and 5, and regression analysis showed SGR reached the maximum in fish fed diet containing 37 g kg−1 fermented E. prolifera, while the feed conversion ratio reduced significantly in fish fed diets 2, 3, 4 and 5, and regression analysis showed it reached its minimum in fish fed diet containing 41 g kg−1 fermented E. prolifera. The pepsin, erepsin, gastric amylase, intestinal amylase, gastric lipase and intestinal lipase activities in fish fed diets 2, 3 and 4 were higher significantly than the control, with the exception of the pepsin activity in fish fed diet 4. The serum total superoxide dismutase, lysozyme, acid phosphatase and alkaline phosphatase activities enhanced significantly in fish fed diets 3 and 4. In conclusion, fermented E. prolifera had positive effects on the growth performance, digestive enzyme activities and serum non-specific immunity of red tilapia and the recommended dose of fermented E. prolifera is 37-41 g kg−1 in the diet of red tilapia. [ABSTRACT FROM AUTHOR]