The requirement of the gilthead seabream (Sparus aurata L.) for nicotinic acid

Semi-purified diets were used to determine the nicotinic acid requirement of the gilthead seabream, Sparus aurata. Vitamin losses during food manufacture were minimal resulting in dietary levels which were close to the declared content. Dietary nicotinic acid contents of 52·21 mg/kg and below resulted in sub-optimum growth, reduced food efficiency and poor values for apparent net protein utilization. Diets containing less than 28·67 mg/kg gave a low proportion of carcass lipid concomitant with an elevation in the relative content of carcass moisture. Although gross deficiency symptoms were not observed, a reduced hepatosomatic index and a slightly lower plasma glucose concentration were detected amongst the fish given diets supplemented with nicotinic acid at the level of 25 mg/kg or less. Based upon the results of broken line analysis and data derived by modelling the weight gain of the fish, the nicotinic acid requirement of Sparus aurata fingerlings lies between 63 and 83 mg/kg of diet or 1·57 to 2·07 µg/kg body weight per day.