Effect of Dietary Fatty Acids and Cholesterol on Growth and Fatty Acid Composition of the Chicken

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Abstract
Addition of safflower oil or methyl linoleate, but not methyl linolenate, to purified diets free of unsaturated fatty acids resulted in an immediate (within 7 days) growth response in chickens. Addition of a mixture of methyl myristate and methyl laurate depressed growth, and addition of cholesterol to these saturated fatty acids depressed growth further. These growth-depressing effects were largely overcome by addition of a source of linoleic acid. Analysis of depot fat, heart, liver, testis and cerebrum using gas-liquid chromatography revealed that dietary linoleic acid profoundly affected the fatty acid composition of tissues analyzed. In tissues of chickens fed linoleic acid-free diets the level of fatty acid tentatively identified as a C-20 triene was elevated and the linoleic and arachidonic acid content was very low; there was no detectable (< 0.1%) linoleic acid in testis, cerebrum, or depot fat, whereas all tissues except depot fat contained at least 1.5% of arachidonic acid. Methyl laurate and methyl myristate supplementation increased tissue levels of these fatty acids but had no effect on the per cent linoleic acid or arachidonic acid. Addition of linoleic acid resulted in a decrease in percentage of C-20 triene and an increase in the linoleic and arachidonic acid in all tissues analyzed.