DIETARY EVALUATION OF BETA-GLUCAN ON GROWTH AND HAEMATO-BIOCHEMICAL RESPONSE OF Clarias gariepinus FINGERLINGS

The ban on the use of antibiotics and synthetic drugs has stimulated research efforts on alternative therapeutic approach to aquatic animal health management. Among the alternative product tested so far, Beta-glucan has become prominent and widely used in aquaculture. Although, several studies have been conducted on the use of Beta-glucan in fish such as Rainbow trout (Ji et al., 2017), Silver catfish (Janine Di Domenico et al., 2017), Tropical gar (Nieves-Rodriguez et al., 2018), however, scanty information is available on African catfish, Clarias gariepinus. Thus, the current study was designed to examine the effect of β-glucan on growth, nutrient utilization, and hemato-biochemical responses of Clarias gariepinus fingerlings.

Beta-glucan (BG) prepared from brewer's yeast (Saccharomyces cerevisiae) was incorporated into the diet at different level viz., 0 g/kg (control), 0.25g/kg (BG 0.25), 0.5g/kg (BG 0.5), 1g/kg (BG 1) and 2g/kg (BG 2). Fifteen fish averaging 4.60±0.01g were distinctly distributed into each tank, in triplicate and fed for 60 days under aerated condition. The fish were fed daily with their respective diets at 9:00 h and 17:00 h. Upon the completion of the feeding trial, growth performance and nutrient utilization indices, hematology, and serum biochemical parameters were analyzed following standard laboratory procedures.

The highest weight gain (WG), weight gain percentage (WG %), daily growth coefficient (DGC), specific growth rate (SGR) and thermal growth coefficient (TGC) were observed in fish fed BG 0.25g/kg which is similar to the control but differ significantly from other fed groups (P<0.05). However, the nutrient utilization indices such as feed conversion ratio (FCR), feed intake (FI), protein efficiency ratio (PER), and lipid productive value (LPV) were unaffected (P>0.05). No significant variation was noticed in the whole-body crude protein content whereas significantly higher crude lipid content was recorded in fish fed BG 1%. The administration of β-glucan had no effect (p˃0.05) on the hematology parameters among the various groups; however, the lymphocyte and neutrophil values were significantly influenced by the dietary BG inclusion. The serum total protein, albumin, globulin, and A/G ratio values were not significantly different (P>0.05), while cholesterol, total bilirubin, total antioxidant capacity and glucose concentration differed significantly (P<0.05) among the various experimental groups. The results of the current findings showed that the addition of β-glucan at a level not higher than 0.25g/Kg positively enhanced the growth, lymphocyte level, and reduces cholesterol, total bilirubin, and glucose concentration of Clarias gariepinus.