Effects of varying forms of dietary ascorbic acid on the nutrition, histology and ultrastructure of the gills, livers and kidneys of groupes, Epinephelus malabaricus
1993
Wutiporn Phromkunthong | Mali Boonyaratpalin | Volker Storchl
12-weeks growth and histological study was conducted to evaluate the effects of crystalline ascorbic acid, glyceride-coated ascorbic acid and ascorbyl 1-2-monophosphate-magnesium in diets for grouper (Epinephelus malabaricus). All three forms were added to a basal diet containing no ascorbic acid. In terms of growth, weight gain and feed efficiency, fish fed diets supplemented with glyceride-coated ascorbic acid and ascorbyl 1-2-monophosphate-magnesium performed better results than fish fed diets without ascorbic supplementation or supplemented with crystalline ascorbic acid. Survival rate of fish in all treatments performed well. Fish fed the diet without ascorbic acid supplementation performed poor and showed clinical signs of ascorbic acid deficiency such as haemorrhages of fins, deformed operculae and caudal fin erosion. Histological observation of the gills of scorvutic fish showed hyperplasia of primary and secondary lamellae, gill fusion, gill cartilage distortion and separation of gill epithelia from the connective tissue of the secondary lamellae. By transmission electron microscopy, the degeneration of chloride cells, mucous cells and epithelium cells as well as of hyperplasia and edema of epithelium cells were observed. Liver cells exhibited high vacuolation and a decrease of glycogen content. However, histopathology in the kidneys of ascorbic acid deficient grouper was not detected. Grouper fed diets supplemented varying forms of ascorbic acid did not develop any abnormalities in any organs examined.
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