Dietetic Metabolites of Non-Pathogenic Escherichia Coli Enhanced Growth, Immunity, and Gut Bactericidal Activity of African Catfish, Clarias Gariepinus

Abstract

Dietetic probiotics stimulates growth, gut health, and physiological functions in fish however, their undesirable interactions in the gut of fish have been reported. Hence, this study assessed the effect of non-pathogenic Escherichia coli metabolite (NPECM) containing nineteen identified bio-active constituents as suitable alternative to enhance the growth, gut health, and non-specific immunity of African catfish (8.80±0.36g, n = 255). Isonitrogenous diets (400 g/kg crude protein) containing sequential NPECM additive of 5.0 g/kg from 0.0 (control) – 20.0 g/kg were administered to African catfish twice daily at satiation for 12 weeks. Post-feeding challenge using intraperitoneal pathogenic Vibrio species at 0.4 × 106 CFU/ml dose was administered to the experimental fish and observed for 2 weeks. Dietetic NPECM significantly (P < 0.05) enhanced growth by 35.7% (0.0 – 10.0 g/kg NPECM). Hematologic profiles and non-specific immunity significantly (P < 0.05) improved with increasing dietetic NPECM (0.0 – 20.0 g/kg) however, the liver enzymes were not significantly (P > 0.05) affected, thereby underscoring better oxygen carrying capacity, immune response, and reduced cellular damage. In addition, gut health significantly (P < 0.05) improved with dietetic NPECM boost as histomorphometry indices enhanced, while bacterial counts (CFU/g) decreased. The post-infection recovery was noticed to improve in African catfish fed 10.0 – 20.0 g/kg dietetic NPECM with 50% survival rate. Therefore, in terms of improved growth, non-specific immunity, gut bactericidal activity, and post-infection recovery, the study concluded that African catfish performed best with dietetic NPECM, and optimum response established at 10.0 g/kg NPECM inclusion.

Keywords: African catfish, dietetic probiotics, non-pathogenic Escherichia coli metabolites, Growth, non-specific immunity