Growth, feed utilization, mineralization and antioxidant response of stinging catfish Heteropneustes fossilis fed diets with different levels of manganese

Abstract

The present research was organized to assess the effects of varying dietary levels of manganese on growth, feed efficiency, mineralization and antioxidant response of fingerling stinging catfish Heteropneustes fossilis (7.84 ± 0.08 g). Isonitrogenous (400 g kg−1 crude protein) and isocaloric (17.89 kJ g−1 gross energy) casein-gelatin based purified diets containing varying levels of manganese (1.85, 3.79, 5.92, 7.68, 9.82, 12.09 and 13.96 mg kg−1) were formulated and fed to triplicate groups of fish for a period of 12 week. MnSO4.H2O was used as the dietary manganese source. Absolute weight gain, protein gain, protein efficiency ratio and feed conversion ratio were found to improve with increasing dietary manganese level from 1.85 to7.68 mg kg−1 diet and then stabilized. Whole body protein and moisture content were found to improve with increasing dietary manganese level up to 7.68 mg kg−1 followed by no change on further increase in dietary manganese. On the other hand, whole body fat reduced with increasing dietary manganese level up to 7.68 mg kg−1 and then stabilized. However, body ash was not significantly (P > .05) affected by graded levels of dietary manganese. Whole body and vertebrae mineralization was also affected by dietary manganese levels. Except whole body copper, zinc and vertebrae zinc concentration all other minerals such as manganese, iron, calcium and phosphorus were significantly (P < .05) affected with increasing dietary manganese levels. Hepatic antioxidant enzymes activity, total superoxide dismutase, manganese superoxide dismutase and catalase activity were found to improve with increasing dietary manganese levels from 1.85 to 7.68 mg kg−1. Malondialdehyde concentration exhibited decreasing tendency (P < .05) with incremental manganese levels in the diets from 1.85 to 7.68 mg kg−1 and then stabilized. Condition factor and hepatosomatic index were also found to decrease with increase in dietary manganese levels while viscerosomatic index did not show any change in response to variable levels of dietary manganese. Broken-line regression analysis of absolute weight gain, protein gain, vertebrae manganese and hepatic Mn-SOD activity against variable levels of dietary manganese depicted the optimal dietary manganese requirement for fingerling H. fossilis ranging between 7.81 and 8.16 mg kg−1 diet.