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A 9-week study was conducted to evaluate the potential of processed animal protein ( PAP) in comparison with soybean meal ( SM) to replace fish meal ( FM) in practical diets for European catfish, Silurus glanis, on growth performance, liver transaminase activities and expression of growth-related genes. Seven isonitrogenous (440 g kg-1 crude protein) and isoenergetic (16.70 MJ/kg) practical diets were formulated by replacing 0 (control), 30%, 60% and 100% FM with either SM or PAP. Each diet was randomly assigned to triplicate groups of 25 fish per cages fixed in the pond. Fish fed the diet substituted 100% FM from SM or PAP had lower ( p < .05) growth performance, feed efficiency and protein retention compared to control and other groups. The decreased growth performance occurred concomitant with a decline in the expression level of liver GHR/ IGF-I axis genes. The gene expression and activity of liver protein metabolism enzymes also positively correlated with growth performance. Findings of this study indicated that both SM and PAP were equally effective in replacing FM up to 60% in the practical diet of Silurus glanis. Total replacement of FM either with SM or PAP induced negative influences on growth and feed utilization. [ABSTRACT FROM AUTHOR]

This study investigated the modulating effect of temperature variation on the metabolic status and growth performance of tropical freshwater fish, Labeo rohita, when reared with starch-based gelatinized (G) or non-gelatinized ( NG) diet. Fish were either maintained at ambient water temperature (26 °C) or exposed to 32 °C for 1 week, and then subjected to 26 °C for 4 weeks. Both groups were fed with isoproteinous (300 g kg−1) diets containing G or NG starch. A significant interaction was evident between increased metabolic activity due to the short-term exposure to higher temperature and starch type on growth performance, feed efficiency and protein retention. Dietary starch type and water temperature interactions were more effective in modulating the hepatic glucokinase and pyruvate kinase responses than that of hexokinase. Hepatic aspartate amino transferase and alanine amino transferase activities were augmented at low temperature in NG starch fed group. Overall, our findings indicate that enzyme activities are enhanced due to the short-term exposure to higher temperature (32 °C). This elevated temperature lasted for 3 weeks after exposure during which NG starch tended to support the growth. [ABSTRACT FROM AUTHOR]