Effects of Dietary Aflatoxin B1 on Hybrid Striped Bass (Morone chrysops x M. saxatilis) and Assessment of Supplemental Arginine as a Potential Aflatoxicosis Alleviator
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abstract
Aflatoxin contamination of feeds poses a significant threat to aquaculture. This six-week study was conducted to evaluate the impact of aflatoxin B1 (AFB1) in diets with and without supplemental arginine (Arg) on the production performance, somatic indices, body composition, and immune responses of hybrid striped bass (HSB). Six experimental diets were formulated to contain different levels of AFB1 (0, 1, or 2mg/kg) and supplemental Arg (0 or 2%) following a 32 factorial arrangement. Triplicate groups of HSB (~5.44g/fish) stocked in 18 glass aquaria were randomly assigned each diet and fed at a rate approaching apparent satiation twice daily. At the conclusion of the feeding trial, no interactions among dietary AFB1 and Arg were found. However, both medium (~1mg/kg) and high (~2mg/kg) levels of dietary AFB1 caused severe toxic effects on HSB directly affecting performance. Relative to control groups without AFB1 supplementation, steep reductions in weight gain (from 553% to 120% of initial weight), feed efficiency ratio (from 0.96 to 0.36), and protein retention (from 43% to 12%) were found in fish fed diets containing medium AFB1, and further reductions were observed in groups exposed to high AFB1. Dietary AFB1 also negatively affected condition factor and somatic indices and reduced whole-body protein and lipid contents relative to control groups. Significantly lower plasma hemolytic and lysozyme activities were found in fish exposed to dietary AFB1. Despite no significant protective effect of supplemental Arg being observed for most response parameters, reduced levels of Arg in plasma and muscle of AFB1-fed HSB indicated increased catabolism under nutritional stress. In conclusion, this study demonstrated that exposure to dietary AFB1 concentrations of ~1 and 2mg/kg severely affected HSB and that supplemental Arg above requirement levels may be ineffective in alleviating aflatoxicosis.
