Abstract:

Isonitrogenous and isocaloric diets containing 0, 18 or 36%
toasted full-fat soybean meal (FFSM) were fed to Atlantic
halibut. The diets were fed to five tanks of fish each for
34 days (period 1). Four tanks from each treatment were then
retained in the growth experiment for a further 32 days
(period 2), while the groups of fish from one tank from each of
the 0 and 36% FFSM groups were split and transferred to two
metabolism tanks each. The initial weight of the fish in the
growth trial was 169 ± 1 g (mean ± SEM, n ¼ 12; weight
range 89–253 g) and the final weight was 317 ± 5 g. There
was no significant effect of dietary treatment on specific
growth rate (range, 0.8–1.1% day)1), feed consumption (0.5–
0.7% body weight day)1), feed efficiency (1.3–1.6 g wet gain g
dry feed)1), protein retention (48–55%) or energy retention
(49–57%). The fat, protein and energy concentrations in the
fish increased during the trial and were not affected by the
diet. The hepatosomatic index in fish fed with 36% FFSM
diet was significantly lower (1.7%) than in the other groups
(2.2%) (P < 0.05). No differences in intestinal morphology
were observed between dietary treatments and no pathological
reactions were identified in any of the samples. In the
metabolism trial, there were no significant differences in
oxygen consumption or ammonia excretion between fish fed
with 0 and 36% FFSM diets. In conclusion, up to 36% FFSM
may be added to diets for Atlantic halibut without negative
effects on growth, feed efficiency or intestinal morphology.