High Hog Prices Boost Smithfield Foods  CHICAGO  (Reuters) - Smithfield Foods Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=SFD.N target=/stocks/quickinfo/fullquote"&gt;SFD.N&lt;/A&gt;, the  largest U.S. pork producer, on Tuesday reported quarterly  earnings jumped 61 percent on high hog prices, strong pork  exports and the acquisition of a pork processor.