Linolenic acid supplementation in the diet of European cat®sh (Silurus glanis): eect on growth and fatty acid composition

Summary In an 18-week treatment, the eect of linolenic acid on European cat®sh (Silurus glanis L.) growth indicators was investigated as to weight gain, feeding coecient (FCR value), speci®c growth rate (SGR value), protein eciency ratio (PER value), productive protein value (PPV) and survival rate. Concurrently, the ®shmeat chemical composition was also investigated. The experiment was organized into four groups, each divided into three subgroups. Stocked in each of 12 cages were 30´1-year-old cat®sh, with individual weights ranging from 148.5 to 151.5 g/ind. All ®sh were given standard feed for European cat®sh which contained 45% protein. The ®rst batch, control group (C), received no additional linolenic acid. Linolenic acid was added to the feed of the second (E 1 ), third (E 2 ) and fourth group (E 3 ), at 0.5, 1.0 and 1.5%, respectively. Growth indicator improvement was best in the E 2 group fed the 1% linolenic acid, whereby the ®sh weight gain was 12.6% higher and the feeding coecient 12.9% lower, while SGR, PER and PPV values were 6.1, 12.0 and 15.8% better than the control group. Growth indicators were also signi®cantly (P < 0.01) improved in the three groups receiving additional linolenic acid in comparison to the control group. Moreover, this addition positively aected ®shmeat quality by increasing meat protein content from 18.04% (C) to 18.79% (E 3 ). The total unsaturated fatty acid content also increased from 65.07% (C) to 69.82% (E 3 ), and the total saturated fatty acid content decreased from 31.36% (C) to 26.50% (E 3 ); consequently, the ratio of unsaturated to saturated fatty acids increased from 2.07% (C) to 2.63% (E 3 ). It can be concluded that the addition of 1% linolenic acid to standard cat®sh feed has bene®cial eects on ®sh growth indicators and meat quality