Riboflavin requirements in carp [Cyprinus carpio] and rainbow trout [Salmo gairdnerii]

The requirements and deficiency symptoms of riboflavin and the availability of riboflavin retrabutyrate were investigate wity the carp, Cyprinus carpio, and the rainbow trout, Salmo gairdneri. The intestinal homoginate of the rainbow trout was found to hydrolyze riboflavin tetrabutyrate and to liberate riboflavin from the ester. The feeding experiwents with these fish species also revealed that the riboflavin-ester was available like free ribofalvin. The fish fed diets containing riboflavin tetrabutyrate accumulated riboflavin in the liver or hepatopancreas. The anorexia, poor growth, and high mortality rate were observed in both fish species as the general deficiency symptoms of riboflavin. Together with these symptoms, hemorrhage of the skin and the fins in the carp and lesion of the fins and cataract in the rainbow trout were characteristic signs of the deficiercy. The dietary riboflavin levels required to provide the maximum storage of the vitamin in the hepatic tissue were 0.7 mg in the carp and 0.6mg in in the rainbow trout/100g dry tiet, respectively. The riboflavin requirements of these fish species were not influenced by the dietary lipid levels.