The effects of replacing fish oil with vegetable oils in starter feeds on the liver fat composition of sea bass (Dicentrarchus labrax L., 1758)

Abstract

The effects of replacing fish oil with soybean oil, sunflower oil, corn oil and olive oil in starter feeds on the vicerosomatic index, hepatosomatic index and liver fatty acid composition of the sea bass were studied. Juvenile sea bass (initial weight = 7.58 +/- 0.13 g) were fed experimental diets for 75 days. The fish were then killed and liver samples were collected. The lowest total crude fat value (17.61%) was found in the fish fed the fish oil diet. The highest total crude fat value (34.30%) was found in the fish fed the olive oil diet (P < 0.05). Similarly, the fish fed the fish oil diet had the lowest hepatosomatic index value (2.08) and all the fish fed vegetable oils had similarly high hepatosomatic index values (P < 0.05). Likewise, vicerosomatic index values were lowest (9.06%) in the fish fed fish oil and highest in the fish fed soybean and other vegetable oils (P < 0.05). Fatty acid analyses showed that EPA and DHA from n-3 HUFA's in the fish fed the fish oil diet, linolenic acid (18:3n-3) and linoleic acid (18:2n-6) in the fish fed the soybean oil diet and oleic acid (18:1n-9) in the fish fed the olive oil diet were higher than in the fish fed the other diets.