A 73-day feeding trial was conducted to determine the effects of the freshness of poultry by-product meal on the growth performance, immune response and hepatopancreatic health of giant freshwater prawn, Macrobrachium rosenbergii. Three semi-purified diets were formulated containing 2.5 % poultry by-product meal with different TVB-N value, designated as L group (untreated poultry by-product meal, TVB-N 10 mg/100 g, i.e., dietary TVB-N 55 mg/100 g), M group (TVB-N 300 mg/100 g, i.e., dietary TVB-N 60 mg/100 g), and H group (TVB-N 450 mg/100 g, i.e., dietary TVB-N 68 mg/100 g), and fed to three groups of prawns (initial weight: 0.82 ± 0.01 g), respectively. Results showed that the weight gain rate (WGR) and specific growth rate (SGR) of prawns significantly decreased with the TVB-N value increased (P < 0.05). The survival rate (SR) and hepatosomatic index (HSI) of prawns in group M and group H were significantly decreased (P < 0.05), while the feed conversion ratio (FCR) was significantly increased (P < 0.05). In addition, the lipase (LPS) and α-amylase (α-AMS) activity of prawns in group L was significantly higher than that in group H (P < 0.05). With the poultry by-product meal TVB-N value increased, the activity of total superoxide dismutase (T-SOD) and glutathione S-transferase (GST) was significantly decreased. RT-qPCR results showed that the expression of bok in group H was significantly higher than that in group L and group M (P < 0.05), the expressions of caspase3, caspase9, bax, and nf-κb in group H were significantly higher than that in group L (P < 0.05). High temperature stress and ammonia nitrogen stress significantly decreased the cumulative survival rate of prawns in group M and group H. Conclusively, it is necessary to guarantee the freshness of the ingredients in prawn formulated diets, and the TVB-N value of diets is recommended not to exceed 60 mg/100 g.
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