We have always been able to keep our intact males together.  We have had 5 ranging in age from 1 year old to 3 years old and they used to get along fine.  2 of the 5 are breeding, a 2 year old and a 3 year old.  Even though they knew the other had bred, they've always continued to share a pasture and get along just fine. 

We took our herd to be shorn at another farm and one of our studs (the 2 year old) stayed there for a month to do some breedings.  When we brought him back home a few weeks ago, our 3 year old went ballistic.  They hate each other.  I'm all for letting them work out their differences, but we had to separate them for fear they were going to kill each other.  Now there is a full pasture between them and they spend half the day pacing and glaring at each other; sometimes rearing up on the fence.  We've even had to reinforce the fence because our wonderful sweet boys are pushing it down trying to get to each other.  It's become such a problem when we try to do breedings (even though we do them in a private area where the other herdsire can't see).  The male doing the breeding is more interested in figuring out where the other male is; it's hard to get him to focus on the female.

Do they not recognize each other shorn since they didn't come back from the shearing together?  Is the 2 year old just getting old enough to naturally want to fight the 3 year old?  Should we just let them duke it out and get it over with?  It is much more then a little show with some chest butting.  It is full fledged war with screaming, biting, body slamming....I'm worried they're going to die of heat exhaustion the way they carry on.  The only good news is that they are both very easy for me to handle and have always let me handle them without much fuss. 

Males can certainly be challenging.  The shearing is probably a contributing factor but I also find that many males change from play fighting to the real thing right around 3 years of age and it could very well be that the 3 year old is getting old enough to really be territorial and the 2 year old is now big enough to represent a threat.

The bottom line is that unless you move to the barn and plan to stay out there full time you can only address this with your physical layout.  The heat of the summer may limit their activity and they may settle down on their own but if they don't, there are a few things you can try.  If you do put them together I would do it early in the morning or later in the evening when it is cooler but it sounds as if this is going to be more than you want to deal with.  You might try changing which pasture they are in; other words swap them to each others pastures.  Provided you have enough room, if you can get them out of sight of one another that would probably be your best bet.  “Out of sight out of mind.”  You could try putting some valerian (hebal) or an appropriate homeopathic remedy in their water...calms forte is one you could try.  You might try getting a helper and putting them both on leads and working them through obstacles together passing close by each other while you control their behavior... by keeping them busy.  Taking walks around and about your farm or out in the fields may help.  You will obviously need to pay close attention as you lead them and work with a partner who is also confident and competent on the lead rope. 

Marty