<p><P>PROBLEM TO BE SOLVED: To provide a nutritional technique efficiently enhancing the content of highly-unsaturated fatty acid which is a functional component in the milk of a ruminant livestock. <P>SOLUTION: The expression of the gene encoding fatty acid desaturase 2(FADS2) in the mammary gland tissue cells of the ruminant livestock and/or the activity of the enzyme are enhanced by administering or supplying animal medicine or animal feeding stuff composition containing nutrients such as acetic acid, menaquinone-4, arachidonic acid to the ruminant livestock. Thereby, the content of the highly-unsaturated fatty acid in the mammary gland tissue cells and the milk is efficiently enhanced. <P>COPYRIGHT: (C)2012,JPO&INPIT</p>
