Effects of dietary iron on growth, haematology, oxidative stress and hepatic ascorbic acid concentration of stinging catfish Heteropneustes fossilis

Abstract

This study was aimed to evaluate the effects of dietary iron on growth, haematology oxidative stress and determine the optimum dietary iron level for Heteropneustes fossilis by feeding graded levels of iron (6.9, 25.5, 47.0, 66.7, 86.6, 107.1, 126.8 and 146.9 mg kg−1) achieved by supplementing ferrous sulfate (0, 99.4, 198.8, 298.2, 397.6, 497.0, 596.4 and 695.4 mg kg−1). Increase in dietary iron levels from 6.9 to 86.6 mg kg−1 significantly improved (P < 0.05) the growth performance and conversion efficiencies in terms of absolute weight gain (AWG; 50.4 g fish−1), feed conversion ratio (FCR; 1.6), specific growth rate (SGR; 2.5% day−1) and protein retention efficiency (PRE; 28.2%) beyond which no significant change was observed. The concentration of iron in liver also increased up to 86.6 mg kg−1 while whole body iron increased up to the level of 107.1 mg kg−1 and then stabilized. Red blood cells (RBC) counts, haemoglobin (Hb), haematocrit (Hct), mean cell haemoglobin (MCH) and mean corpuscular volume (MCV) also improved up to 86.6 mg kg−1 and then stabilized. Activities of hepatic superoxide dismutase (SOD) and catalase (CAT) were found to increase while malondialdehyde (MDA) content decreased with increasing levels of dietary iron up to 86.6 mg kg−1. Hepatic ascorbic acid concentration was found to decrease up to 86.6 mg kg−1. Based on broken-line regression analysis of AWG, PRE, Hct and serum iron concentration against increasing levels of dietary iron, optimum level of dietary iron for H. fossilis was found to range between 82.51 and 86.05 mg kg−1 of dry diet.