"farming cows" is pretty impossible about now and quite pointless. 1.3m for one mob for a 5man group? Cool if you're all bis. And it might drop something, it might not.
Cow king is a whole other story with it's 23m for a 5man group (which has 3 dps, right). That comes down to each of them doing 7.66m dmg to kill it equally. That'd take almost 11 minutes if each of them did 12k dps witch is then again impossible since no 30% buff, not a steady target, it has phases and stuff. So yea, you need a solid 20-25m to kill it if you dont fail anywhere or your healer doesnt go OOM.
But if anyone managed to kill it please lemme know what are the drops, I'm really interested.