I don't believe the rates need to be changed at all for blue organs, but red organs are quite a pain, I feel like u should atleast get a set from a cow game, as I only find one per game usually and it tends to be the same one over and over, BUT I will note that blue organs are extremely easy to get and very cheap to buy. so if you want to do infernal cows, just go game to game asking if people have blue organs they want to sell!