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Title: Oscars, astronotus ocellatus, have a dietary requirement for vitamin C
Authors: Fracalossi, Débora Machado
Allen, Mary E.
Nichols, Donald K.
Oftedal, Olav T.
Keywords: Ascorbic Acid
Gulonolactone Oxidase
Animals Experiment
Animals Tissue
Ascorbic Acid Deficiency
Body Weight
Controlled Study
Diet Supplementation
Intraocular Hemorrhage
Muscle Atrophy
Nutritional Requirement
Analysis Of Variance
Ascorbic Acid
Ascorbic Acid Deficiency
L-gulonolactone Oxidase
Nutritional Requirements
Sugar Alcohol Dehydrogenases
Issue Date: 1998
metadata.dc.publisher.journal: Journal of Nutrition
metadata.dc.relation.ispartof: Volume 128, Número 10, Pags. 1745-1751
Abstract: We found that vitamin C is an essential nutrient for an Amazonian ornamental fish, the oscar (Astronotus ocellatus). This was demonstrated by the absence of L-gulonolactone oxidase activity, the enzyme responsible for the biosynthesis of vitamin C, in liver or kidney of oscars and by a feeding trial in which oscars without vitamin C dietary supplementation developed clinical deficiency signs. Fish weighing 29.2 ± 1.9 g were divided into four groups, and each group was fed a casein-based semipurified diet containing 0, 25, 75 or 200 mg ascorbic acid equivalent (AA)/kg diet for 26 wk. Vitamin C was supplemented in the diets as L-ascorbyl-2-polyphosphate, a mixture of phosphate esters of ascorbate, which is more stable to oxidation than AA. At the end of 26 wk, fish fed no AA had significantly lower weight gain than fish fed the AA-supplemented diets (P < 0.05). Oscars without dietary AA supplementation gained only 37% of their initial weight, compared with 112, 102 and 91% gained by fish fed 25, 75 and 200 mg AA/kg diet, respectively. After 25 wk without dietary supplementation of AA, fish began to develop clinical deficiency signs, including deformed opercula and jaws, hemorrhage in the eyes and fins, and lordosis. Histology indicated that fish without AA supplementation had deformed gill filament support cartilage and atrophied muscle fibers. Collagen content of the vertebral column was significantly lower in fish devoid of dietary AA (P < 0.05). Liver AA concentration varied in proportion to dietary concentration of AA. The minimum dietary AA concentration tested in this study, 25 mg AA/kg diet, was sufficient to prevent growth reduction and AA deficiency signs in oscars.
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