The requirement and toxicity of selenium in rainbow trout (Salmo gairdneri).
This study measured the dietary selenium requirement of rainbow trout and their response to excessive levels of dietary selenium. A dietary selenium level of 0.07 microgram/g dry feed with a waterborne selenium level of 0.4 +/- 0.2 microgram/liter and a dietary vitamin E level of 0.4 IU/g dry diet was sufficient to prevent frank selenium deficiency symptoms. Maximal plasma GSH.px activity was obtained at a dietary selenium level between 0.15 and 0.38 microgram/g dry feed which is less than the average selenium concentration of commercial diets. Chronic dietary selenium toxicity occurred at 13 microgram selenium/g dry feed. Major effects of selenium toxicity were reduced growth rate, poor feed efficiency and a high number of mortalities. No histopathological lesions or significant deviation in the investigated blood parameters or liver somatic index were detected in trout raised on diets containing 13 microgram selenium/g dry feed. Tissue selenium analysis indicated that trout can maintain homeostasis with dietary selenium levels up to 1.25 microgram/g dry feed. The selenium uptake and accumulation in tissues of trout reared on diets containing in excess of 3 microgram/g dry feed may ultimately be toxic to trout if maintained over long periods of time.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005979:Glutathione Peroxidase / Q000097:blood; D006706:Homeostasis; D009751:Nutritional Requirements; D012487:Salmonidae / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism* / Q000633:toxicity; D014337:Trout / Q000378:metabolism*
D005979:Glutathione Peroxidase; D012643:Selenium