Effects of different suboptimal dietary protein levels on growth, nutrient utilization and physio‐metabolic status of Anabas testudineus fingerlings in inland saline water

Abstract

A 60-day feeding trial was conducted to illustrate the effect of suboptimal crude protein (CP) levels on growth and physio-metabolic status of Anabas testudineus fingerlings reared in inland saline water (ISW) at 8 g/L salinity. Six isoenergetic (16 MJ/kg) and isolipidic (60 g/kg) diets with 240 (T24), 260 (T26), 280 (T28), 300 (T30), 320 (T32) and 340 (T34) g suboptimal CP/kg diet were formulated. Weight gain (%) and specific growth rate were significantly higher (p < .05) in T32 and T34 groups. Feed conversion ratio was significantly lower (p < .05) in T30 and T32 group than the other groups. The protein utilizing efficiency was significantly (p < .05) decreased beyond 320 g CP/kg diet. The protease activity was significantly increased (p < .05) up to 320 g CP/kg diet, whereas amylase activity was significantly higher (p < .05) in 240–260 g CP/kg diets. The transaminase enzyme activities were significantly higher (p < .05), and energy demanding enzymes were significantly lower (p < .05) in 300–340 g CP/kg diets. Fish of T24 and T26 groups had lowest (p < .05) glycogen, erythrocyte count and total protein with highest (p < .05) glucose and antioxidant enzyme activities. In conclusion, feeding 320 g CP/kg diet is recommended for cost-effective growth of A. testudineus reared in ISW at 8 g/L salinity.