No such thing! Seriously. With regards to arachidonic acid, even corn fed cows have relatively little omega 6. It`s actually a misconception that feeding grains to cows makes them produce much more omega 6, only less omega 3 and a few fat-soluble nutrients.
Not sure about growth hormones or antibiotics, I just know that in Canada there isn`t much to worry about. I would personally err on the side of mysterious manufacturing substances than omega 6. Grass-fed has lots of good CLA and makes it easier to get a badass PUFA ratio so that`s still my vote no matter what.
Stabbing conventional wisdom in its face.
Anyone who wants to talk nutrition should PM me!