A feeding experiment was conducted to compare the EFA value between eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in juvenile red seabream, and to determine their requirements for both fatty acids by feeding them defatted fish meal diets containing different levels of EPA and/or DHA ranging from 0 to 1% in diet.Juvenile red seabream fed a diet without supplemental EFA began to show a high mortality and poor appetite after one week feeding. The cumulative mortality of this group was 46% after 24 days. The growth and feed efficiency were effectively improved by elevating EPA or DHA levels to 1% or 0.5% in the diet, respectively. However, further elevation of the DHA level from 0.5 to 1% and addition of both EPA and DHA in diets at levels of 0.25 and 0.5% each did not result in further improvement of these parameters. The hepatosomatic index was high in the fish fed low levels of EPA or DHA and was reduced by elevating EPA levels to 1% in diets, although DHA w as more effective than EPA.Thus, the requirement of EPA and DHA was estimated to be around 1% and 0.5% in diet for juvenile red seabream, respectively. The EFA efficiency of DHA was also found to be about twice as high as that of EPA, and there was no additive effect of EPA and DHA on growth and feed efficiency.
Feeding experiments were conducted to determine the requirements of early juvenile red sea bream (Pagrus major) for eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) by feeding Arte mia nauplii containing different levels of EPA or DHA for 12 days. Juveniles fed EPA-enriched Arte mia had a high survival rate but very poor vitality, while those fed on Artemia enriched with DHA had both a high survival rate and vitality. The vitality of fish was effectively improved by elevation of DHA levels in Artemia. In the DHA-enriched Artemia, the EPA content increased from the initial value together with the appearance of docosapentaenoic acid (DPA), indicating retroconversion from DHA to EPA through DPA in the nauplii. The requirement of early juvenile red sea bream for DHA was esti mated to be 0.95-1.62% in Artemia on a dry matter basis when vitality was used as an index, and was satisfied with 2.25% EPA or 0.95% DHA (2.05% n-3 HUFA) on a dry basis when based on the survival rate.
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