Pantothenic acid deficiency detection in rainbow trout (Oncorhynchus mykiss)

Rainbow trout averaging 150 g were fed semipurified diets supplemented or not supplemented with pantothenic acid. After 16 wk of feeding, fish fed the deficient diet had reduced feed intake. At 28 wk, supplemented fish weighed > 600 g, whereas deficient fish weighed 425 g. Deficient fish became anorectic and listless at 25 wk and began to die at 28 wk. Histological examination of gill tissue revealed fused gill lamellae in the deficient fish, confirming pantothenic acid deficiency. At 4-wk intervals, samples of fish were taken from each group for determination of free and total concentrations of pantothenic acid in gills, liver, heart and erythrocytes by RIA. Concentrations of bound pantothenic acid, calculated by difference, did not differ between dietary treatment groups except in gills. Free pantothenic acid concentration in gills and heart were significantly lower in fish fed the deficient diet than in those fed the complete diet after 4 wk of feeding and remained so thereafter. Free pantothenic acid concentrations in the livers of deficient fish were significantly different from those in sufficient fish after 16 wk of feeding. Erythrocyte free pantothenic acid concentrations of deficient fish were significantly different from initial values at 8 wk and beyond. Using free pantothenic acid concentrations in erythrocytes allows detection of pantothenic acid deficiency in fish that are too valuable to permit destructive sampling techniques, such as broodstock and threatened or endangered species.