THE REQUIREMENT OF THE GILTHEAD SEABREAM (SPARUS-AURATA L) FOR NICOTINIC-ACID

Semi-purified diets were used to determine the nicotinic acid requirem ent of the gilthead seabream, Sparus aurata. Vitamin losses during foo d manufacture were minimal resulting in dietary levels which were clos e 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 concomit ant with an elevation in the relative content of carcass moisture. Alt hough guess deficiency symptoms were not observed, a reduced hepatosom atic index and a slightly lower plasma glucose concentration were dete cted 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 a nalysis 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 mu g/kg body weight per day.