Vitamin A Deficiency in Cherry Salmon

Abstract

Cherry salmon Oncorhynchus masou (also called amago salmon) were fed a diet with no vitamin A, and control fish were fed the same purified diet but with 5,000 IU retinyl acetate/ 100 g of diet. After 15 weeks of feeding, the fish deprived of vitamin A displayed nutritional deficiency signs, including reduced growth, pale body color, red fins, and truncated snout. The group of vitamin A-deficient fish had 5.6% mortality by the end of 22 weeks, whereas the control group had none. Hematological examination revealed severe anemia. Histological examination revealed separation of hepatic laminae and formation of thin collagen fibers between the separated laminae, atrophic and necrotic lesions in the hepatic parenchyma, numerical atrophy in the hematopoietic tissue and compensatory production of fibroadipose tissue, poorly formed bony tissue in the skull and vertebral protuberance, degeneration of skeletal and cardiac muscle fibers, numerical atrophy of pancreatic acinar cells, and thinning of the epidermis accompanied by a decrease in the numbers of mucous cells. These changes were reversed to some degree after 4 weeks on a complete diet. No pathological changes were apparent in the stomach, intestine, pyloric ceca, gills, brain, pituitary, or eyes.