Elevation in Rearing Temperature within Optimum Range Mitigate Immunosuppressive and Metabolic Stress Effect of High or Low Dietary Protein Level in Labeo Rohita Fingerlings

Abstract

In the present study, Labeo rohita fingerlings were maintained either at ambient water temperature (26ºC) for five weeks or exposed to 32ºC for one week then later maintained at 26ºC for four weeks. Fingerlings reared under different temperature regimes were fed with any of the four experimental diets containing 20, 30, 40 or 45% protein. Serum cortisol level was higher at 26ºC compared to 32ºC, and decrease with the increase in dietary protein level up to 40%. Fingerlings fed 30% and 40% protein recorded similar WBCS count and respiratory burst activity which was lower and higher respectively compared to 20% and 45% protein fed fingerlings. Correspondingly, lower WBCS count and higher NBT were recorded following exposure to higher temperature (32ºC) for one week compared to 26ºC exposure group. Significantly lower survival was recorded in groups fed with lowest (20%) and highest (45%) dietary protein level whereas fingerlings exposed to 32ºC for one week exhibited higher survival (%) compare to 26ºC. Present results indicate that both lower and higher level of dietary protein may cause metabolic stress to fingerlings, as might consequently lead to the depressed immunity and exposure of elevated temperature (32ºC) for one week mitigates this immunosuppressive effect.