Growth performance, gut morphometry and innate immune profiles of common carp, Cyprinus carpio juveniles fed diet fortified with Mitracarpus scaber leaves extract and its susceptibility to pathogenic bacteria, Aeromonas hydrophila

Abstract

Mitracarpus scaber, an endemic medicinal plant to Nigeria, Africa, has medicinal value. In the present study, Mitracarpus scaber leaves extract (MSLE) was fed to common carp, Cyprinus carpio to evaluate its effect on growth performance, nutrient utilization, gut morphometry, and innate immunity parameters. Four isonitrogenous diets (32% crude protein) containing 0.0, 5, 10, or 15 g MSLE/kg diet were fed to fish (7.52 ±0.23 g) for 12 weeks. After the feeding trial, fish were exposed to pathogenic bacteria (Aeromonas hydrophila) for 14 days. Growth performance, nutrient utilization, and feed intake were significantly improved with increasing MSLE levels up to 10 g/kg diet. Similarly, fish fed MSLE diets increased significantly intestinal villi length/width, and absorption area. Furthermore, activities of respiratory burst, lysozyme, catalase, and superoxide dismutase were significantly higher in fish fed diets containing MSLE levels, and their highest values were obtained at fish fed 15 g MSLE/kg diet. After bacterial challenge, fish mortality was lowest (8.45 ±1.30%) in fish fed 15 g MSLE/kg diet, whereas highest mortality (52.50 ±4.56%) was observed with fish fed the control diet. The present study conjured that MSLE inclusion in fish diets with optimum level of 10 g/kg diet stimulated significantly the performance, nutrient utilization, modified gut morphometry, and innate immune response of common carp. Also, its inclusion protected fish against pathogenic bacteria, A. hydrophila infection.