THE EFFECT OF AFLATOXIN-B1 ON HYBRID STRIPED BASS Morone chrysops × Morone saxatilis AND ASSESSMENT OF DIETARY SUPPLEMENTATION OF ARGININE FOR THE PREVENTION OF AFLATOXICOSIS  

Aflatoxin B1 (AFB1), recognized as a strong carcinogen, has been shown to cause growth stunting, immunosuppression and liver cancer in multiple species. The recent trend of replacing fishmeal with plant-based protein feedstuffs in fish feeds has amplified the AFB1 exposure risk to farm-raised fish. Arginine (Arg) has important roles in the modulation of immune responses. Its influence on health and immune function has received considerable attention in mammalian as well as fish studies, but its potential influence on AFB1 toxicity has not be evaluated. Therefore, this study was designed to: (1) evaluate AFB1 impact on cultured hybrid striped bass over the course of 4 weeks exposure; and (2) assess the effects of Arg supplementation as a strategy to prevent aflatoxicosis. Fish were fed experimental diets based on practical feedstuffs and containing either 0, 2, or 4 mg AFB1/kg diet, with either 0 or 2% additional Arg supplementation in a 2 x 2 factorial arrangement.  Juvenile hybrid striped bass (average initial weight of 5.44 ± 0.20 g/fish) were stocked into 110-L aquaria as groups of 14 fish, and each diet was fed to triplicate groups of fish twice a day. After 4 weeks of feeding, fish fed the AFB1-supplemented diets exhibited obvious signs of ill health such as anorexia, poor weight gain and reduced feed efficiency. Meanwhile, Arg supplementation significantly improved weight gain of fish fed diets contaminated by 2 mg AFB1/kg, but could not change the severe growth reduction caused by the higher level of AFB1 supplementation. Results from the present experiment demonstrate that hybrid striped bass are extremely sensitive to AFB1 toxicity, and dietary supplementation of Arg has potential to improve growth performance and prevent aflatoxicosis.