fed dietary algae. However, Dantagnan et al. (2009) reported that the inclusion of 3 and
6 % macroalgae meal resulted in a significant increase in polyunsaturated fatty acids
(PUFAs), especially EPA (20:5n-3), DHA (22:6n-3) and linolenic acid, in rainbow trout
muscle, and Walker et al. (2009) observed that the arachidonic acid (20:4n-6) levels were
elevated in Atlantic cod Gadus morhua juveniles fed Porphyra (30 % fishmeal replace).
The ADCs of dietary lipid were high, with no significant differences being observed
between treatment groups. The ADCs for protein of all Ulva groups was significantly
higher than the control group, and no differences between the Ulva treatment groups were
observed. In contrast to these findings, previous studies have reported reduced ADCs for
protein (Appler 1985) and lipid (Valente et al. 2006) in fish fed algal meals.
The present experiment indicates that raw Ulva meal has potential as a novel feed
additive for inclusion in diets for rainbow trout juveniles. Dietary inclusion at levels up to
10 % can be used without detrimental effects on the growth performance, nutrient utilization,
digestibility or muscle fatty acid composition. In fact, the inclusion of raw and
autoclaved Ulva meal in rainbow trout diets improved the n-3 fatty acids content in
rainbow trout muscle. Further studies are required to examine the effects on health and
lipid metabolism, but it should be noted that high levels of autoclaved Ulva meal lead to
poorer performance than raw Ulva meal.