General Mills Cereals Going Whole Grain  NEW YORK (Reuters) - General Mills Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GIS.N target=/stocks/quickinfo/fullquote"&gt;GIS.N&lt;/A&gt;, the No. 2  U.S. cereal maker behind Kellogg Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=K.N target=/stocks/quickinfo/fullquote"&gt;K.N&lt;/A&gt;, on Thursday said  all its breakfast cereals would now be made with whole grain as  it seeks to promote healthy eating habits.