title: Hypervitaminosis A in rainbow trout (Salmo gairdneri): toxicity signs and maximum tolerable level.
abstract: Duplicate groups of juvenile trout were reared on practical trout diets supplemented with geometrically increasing levels of vitamin A (as retinyl palmitate) from 4,000 to approximately 8,104,000 IU/kg diet for 16 weeks at 15.2 +/- 0.5 degrees. The major signs of hypervitaminosis A in rainbow trout were growth depression, increased mortalities, abnormal and necrotic anal, caudal, pectoral and pelvic fins, and pale-yellow, fragile livers. The maximum tolerable level of vitamin A in rainbow trout is approximately 904,000 IU/kg diet, whereas levels above 2,704,000 IU/kg diet are toxic. Hypervitaminosis A in trout also resulted in the occurrence of some spinal deformities; however, there was no apparent effect of excess vitamin A on ascorbic acid metabolism. Liver iron levels declined with increasing levels of dietary and liver vitamin A, indicating an effect of vitamin A on liver iron metabolism in trout. No effect of increasing dietary vitamin A was apparent in the mineral content of the kidney, skin-scales and vertebrae.
mesh_terms: D000818:Animals; D001835:Body Weight; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008452:Maximum Allowable Concentration; D012487:Salmonidae / Q000378:metabolism*; D014337:Trout / Q000378:metabolism*; D014801:Vitamin A / Q000008:administration & dosage* / Q000633:toxicity
chemical_list: D014801:Vitamin A