I have never seen 100% no-grain fed pork despite extensive searching online 
and otherwise.  Even the highest quality farmers which give the impression 
of raising organic pigs in the most traditional manner on pasture and acorn 
filled forests, still feed them grains as well.  I also had a bad reaction 
to eating grain fed animal fat.  If grain-fed beef is not a wise choice, why 
would grain-fed anything be?