Requirements of the Female Rat for Linoleic and Linolenic Acids

Abstract

To determine the requirement of the female rat for essential fatty acids, weanlings were fed a fat-free diet supplemented with highly purified ethyl linoleate or ethyl linolenate at several levels. Weight gain, food efficiency, dermal symptoms of deficiency, and fatty acid composition of liver, heart, erythrocyte, and plasma lipids were determined and comparisons made with male rats from earlier experiments. Minimum linoleate requirement of the female rat was estimated as 0.5% of calories, of male rats, as 1.3%. The requirement for linolenate was estimated to be 0.5% of calories for both males and females. The degree of unsaturation of tissues was found to be different for the 2 sexes. Female tissues had lower proportions of total saturated and monoenoic fatty acids and higher proportions of the more unsaturated, long-chain metabolites of oleic, linoleic and linolenic acids. Calculations of the number of double bonds per fatty acid showed that the fatty acids of female tissues contained 1.3 to 1.6 times more double bonds than those of male rats.