Effect of discolored Porphyra meal supplemented-diet on growth performance and lipid metabolism in yearling yellowtail (Seriola quinqueradiata)

For the beneficial use of discolored Porphyra yezoensis (purple laver), we investigated the effects of adding Porphyra meal to diet on the growth performance and lipid metabolism in yearling yellowtail Seriola quinqueradiata. Yearling yellowtails were fed extruded pellets containing 0, 2, or 4% of Porphyra meal for 40 days. The growth performance (i.e., feed efficiency, protein efficiency ratio, and specific growth rate) did not differ significantly among the dietary groups; however, the performance was slightly higher in the 2% Porphyra meal-supplemented diet group and slightly lower in the 4% Porphyra meal-supplemented diet group. In the liver, the lipogenic enzyme activity increased in the 4% Porphyra meal-supplemented diet group and the hepatic gluconeogenic enzyme activity significantly increased in all the Porphyra meal-supplemented diet groups. In the 2% Porphyra meal-supplemented diet group, enzyme activity related to fatty acid oxidation was slightly higher in the liver and significantly higher in the dark muscle. These results indicated that the addition of Porphyra meal to fish feed affects lipid metabolism in yearling yellowtail.