APPLICATION OF THE RECOMMENDATIONS ON VITAMIN REQUIREMENTS OF FINFISHBY NRC (1993) TO SALMONIDS AND SEA BASS USING PRACTICAL AND PURIFIED DIETS

Trials were conducted to determine whether the recent National Researc h Council [NRC (National Research Council), 1993. Nutrient requirement s of fish. National Academy of Sciences, Washington, DC, USA, 114 pp.] data on the vitamin requirements of rainbow trout are (1) sufficient for salmonids fed practical diets, (2) applicable with semipurified di ets containing all vitamins at the recommended levels only and with sa fety margins, and (3) applicable to other selected species of finfish. In the first trial, diets with either semipurified ingredients (diets 1 to 5) or practical ingredients (diets 6 to 8) were hand-fed to near satiety to triplicate groups of rainbow trout (IBW: 2.8 g; 15 degrees C) over a period of 12 weeks. The supply of all vitamins was adjusted to be either at least meeting the NRC (1993) recommended levels (diet s 3, 5, 7 to 8) or much above (diets 1, 4, 6). Results showed that whi le the NRC (1993) requirement levels were adequate as supplements when rainbow trout were fed practical diets, the same level led to depress ed growth performance and nitrogen utilisation in those fed semipurifi ed diets. In a second trial, triplicate groups of chinook salmon (IBW: 9.8 g; 12 degrees C; 16 weeks), were fed semipurified (diets 1 to 4) or practical (diets 5 to 8) diets with graded levels of a vitamin mixt ure at the NRC recommended levels (100 to 200% and 50 to 125%, respect ively). In this species, growth performance and feed utilisation were little affected by the dietary treatments. In two further trials, semi purified or practical diets supplying all vitamins at or above the rec ommended levels were given to European sea bass. Results confirm the a pplicability of the NRC recommendations for salmonids also for the sea bass fed practical diets, but with semipurified diets, modest safety m argins would appear necessary for rainbow trout and seabass with high growth rate. (C) 1998 Elsevier Science B.V.