Not the person you replied to, but I think "animal's diet affects their nutrition" is pretty obvious. For instance, the "omega 3" eggs you see at the supermarket are produced by feeding the chicken a high omega 3 diet. That itself isn't really interesting. The real question is whether going through all that trouble is worth it. In other words, is it better/more cost effective to buy the higher quality animal products at the supermarket (eg. omega 3 eggs) or buy the regular stuff and pop a multivitamin? For omega 3 eggs at least, the answer is the latter. I'd be interested in seeing how it works out for beef.