Soy protein concentrate in diets for Atlantic halibut (Hippoglossus hippoglossus)

Four experimental diets were fed to triplicate groups of Atlantic halibut i n a 2 X 2 factorial design, testing the effects of protein source and the u se of an attractant. The diets contained 61% fish meal (FM) or 37% FM and 2 8% soy protein concentrate (SPC) with or without a coating of squid meal. I n the SPC diets, 44% of nitrogen was supplied from the SPC. The mean initia l fish weight was 633 g, and at the end of the 12-week trial, the mean fish weight was 874 g. There was no significant effect of dietary treatment on specific growth rate (0.43 +/- 0.02% body weight d(-1), mean +/- S.E.M.). F eed efficiency ratio was significantly lower in the group fed the SPC diet (1.22 +/- 0.02) compared with those fed the FM diet (1.28 +/- 0.02), Fish f ed the SPC diets had a higher feed intake (0.64 +/- 0.02%) than those fed t he FM diet (0.59 +/- 0.02%). Addition of squid had no effect on feed intake . The groups fed diets not supplemented with squid were used for determinat ion of whole body chemical composition, and the remaining fish from these g roups were subsequently stripped for feces for digestibility estimations, T here were no effects of protein source on digestibility or protein or energ y retention in whole fish. The fish fed the diet containing soy protein had a slightly higher dry matter (DM) content (P < 0.05), than the fish fed th e diet containing only fish meal. (C) 1999 Elsevier Science B.V. All rights reserved.