Comparative study on phenoloxidase activity of biofloc-reared pacific white shrimp Penaeus vannamei and Indian white shrimp Penaeus indicus on graded protein diet

Abstract

Shrimp aquaculture demands technological advancement that boosts production and environmental sustainability. This study evaluated and compared the growth performance and innate immunity of two species of shrimp (Pacific White shrimp Penaeus vannamei and India white shrimp Penaeus indicus) reared under biofloc technology with different dietary protein levels (Low-25%, Medium-30% and High-35%). As prophenoloxidase (proPO) activity is an important parameter in immune response of shrimp, we focused on the dynamics of prophenoloxidase induced by three different activators (Sodium dodecyle sulfate, SDS, Trypsin & Laminarin). At the end of the experiment, the effect of activators on proPO activity in serum, plasma and hemocyte lysate (HLS) was evaluated in both the species under conventional and biofloc systems with graded proteins. This experiment lasted for a month as nursery rearing followed by 60 days of grow-out culture. There was no significant difference (p < 0.05) in growth performances of both the species reared under biofloc, whereas control group exhibited lower growth. Significantly higher average body weight (ABW), survival and specific growth rate (SGR) were observed in medium protein groups reared under biofloc than the other biofloc groups and control. The medium protein groups also showed significantly lower (p < 0.01) TAN, NO2–N, and NO3–N levels compared to other treatments and the control exhibited considerably higher TAN, NO2–N and NO3–N levels. The proPO activity in serum of both the shrimps were found to be significantly higher (p < 0.05) than the control in which highest proPO activity was observed in SDS activated groups irrespective of the graded protein levels. A similar trend was observed in the plasma of P. indicus in which SDS activated group fed with high protein level showed highest proPO activity, whereas in plasma of P. vannamei trypsin activated groups fed with low protein level showed higher proPO activity than SDS and laminarin activated groups. The HLS of P. vannamei showed highest proPO functioning in trypsin activated group fed with high protein level, whereas in P. indicus, the highest proPO activity was observed in SDS activated group fed with high protein diet. Though in many cases, the groups fed with high protein diet showed highest proPO activity, the low protein and the medium protein groups also exhibited upregulation in the immune response parameter reared under biofloc irrespective of the species. SOD activity of the hemocytes were influenced by different dietary protein levels and better inhibition was observed in HP when compared to control and other treated groups. Thus the native non-SPF Indian white shrimp P. indicus has comparable potential as the SPF Pacific white shrimp P. vannamei in terms of innate immunity, immune response, and growth when reared under biofloc conditions.