Linoleic (ω6) and linolenic (ω3) acids in the diet of fingerling milkfish ( Chanos chanos Forsskal)

Abstract

Feeding trials were conducted to determine the effects of linoleic and linolenic acids on growth, survival, fatty acid composition and liver histology of milkfish. Five isocaloric semi-purified diets were formulated, either lipid-free or containing the following lipids: 7% lauric acid (LA), 6% LA + 1% linoleic acid, 6% LA + 1% linolenic acid, and 6% LA + 0.5% linoleic + 0.5% linolenic acids, and fed to milkfish with an average weight of 1.55 ± 0.25 g. There were no significant differences in growth or survival between fish fed the lipid-free and the LA diets in the five treatments tested. However, growth of fish fed with linoleic and linolenic acids was significantly higher ( P < 0.05) than that obtained in fish fed lipid-free and LA diets. The best growth response (233%) was attained with fish fed linolenic acid alone. Fatty acid analyses of the total lipid showed that lipid-free and LA diets increased the levels of monoenoic acids in the fish. The addition of linoleic and linolenic acids, alone or in combination, suppressed the levels of these monoenes and increased the levels of polyunsaturated fatty acids (PUFA). Histological analyses using light microscopy revealed slight abnormalities in the hepatocytes of fish fed lipid-free and LA diets. Both linoleic and linolenic acids are effective for good growth and survival of fingerling milkfish; however, the effect of linolenic acid on the growth of this species is better than that of linoleic acid.