Sounds like he needs more of a butt-kicker than a low-on-the-totem-pole kind of buddy... I manage 16 horses- after being separated into 4 pastures for a number of years, I came in and changed it all up. I put ALL the horses out together (all the pastures were adjoining, so I opened all the gates up so they could go wherever they wanted)- with enough room, they worked things out just fine. They have enough room to spread out- they go where they want and are happy.
I have three geldings together right now that were not cut until they were 6 years old- one of them is clearly the boss, and he only uses force when necessary. He is an excellent "policeman" and knocks down the mean ones when they need it, but otherwise leaves everyone alone and actually takes turns eating with most everyone. Given enough room, I truly believe most horses will work things out if there are enough of them in the group. That being said, there was MUCH more herd drama when they were in groups of 4-5. I'm not sure if it had to do with some of the horses feeling more comfortable bossing around 3-4 of their buddies, versus 15, or what. Regardless, the herd dynamics right now are perfect. The mares and geldings are all together, as well as a mini who does just fine for herself. Maybe I just have a "special" situation, but they are happy and the amount of bite marks have gone down 95% since I stopped separating them. But, if it were me, I would find someone with a dominant horse to be turned out with your guy. In nature, horses don't have humans deciding who gets turned out together, they work it out on their own (again, given enough room) :) Just my .02
Last edited by tbcrazy; 03-25-2013 at 08:35 PM.