抄録
A feeding experiment was conducted to characterize essential fatty acid deficiency and to determine the effect of dietary n-6 and n-3 fatty acids on growth and histological changes of white fish Coregonus lavaretus maraena. Growth, feed efficiency together with survival rate were lowest in fish fed a diet containing 5% 18:1n-9 as a sole lipid source. On the otherhand, all parameters were effectively improved by supplementation with n-3 fatty acids, and were highest in fish receiving the diet containing n-3 highly unsaturated fatty acids (HUFA) greater than 0.5%. However, 18:2n-6 was found to be ineffective for enhancing growth. Addition of 18:2n-6 to 18:3n-3 did not further improve growth and feed efficiency. The fish fed the 18:1n-9 diet showed swollen pale livers with abnormalities in histological analysis. This abnormal histological condition was improved by supplementation of 0.5% n-3 HUFA. The ratio of 20:3n-9 to 22:6n-3 in the fatty acid composition of polar lipid fractions from the livers, one of the EFA indices for freshwater fish, was highest in the EFA-deficient group and lowest in the fish receiving 1% n-3 HUFA in diet.
These results indicate that n-3 fatty acids are essential for white fish.
