Effect of Dietary Methyl Linolenate on Growth of Rainbow Trout

The growth and histological changes of rainbow trout kept on a diet deficient in essential fatty acid (EFA) are described. Feeding the purified diets containing no fat or no polyunsaturated fatty acids resulted in poor growth, low feed conversion, high mortality, and a shock syndrome. The whole body, muscle and whole viscera of fish fed on EFA deficient diet were considerably high in water content and low in both protein and lipid contents. The content of liver lipid was also high, indicating a sign of fatty liver. On histological examination, the effect of linolenic acid deficiency was clearly recognized in the liver, muscle, kidney and pancreas. The symptoms were almost completely prevented by the addition of 1% methyl linolenate to the diet. It may be concluded from these results that linolenic acid plays an essential role in rainbow trout as assigned to linoleic acid in mammals.