Join Date: Jul 2010
Location: East Central Illinois
2 x 6 horizontal boards should be strong enough. They need to be on the inside of her stall, or she might kick them outside of her stall. The reinforcing 2 x 4's should be vertical and placed about 2' apart. It sounds like a lot of wood, but you won't have to build it twice. I get extra leftover wood at Lowe's on Mondays, after the suburbanites have bought their wood over the weekend, had it cut there, but they don't want to store the extra pieces, so they LEAVE THEM. Believe it or not, Lowe's THROWS IT AWAY, if somebody like me doesn't buy it at a discount, which is currently $1/piece. ;D
I think your mare is displaying food aggression, so I have a few things to check that might help. =D
First, is her hay/grain fed on the wall adjacent to another horse? If so, could you move it away from all other stall walls so that she doesn't think she needs to compete for it?
Second, put some treats in ONLY her grain--my personal preferance is carrots bc I think that they are most digestable, but ANY treat that she prefers would do. Feed her this for maybe, every day for a full month, then gradually reduce and stop the treats. This will form a habit for her, and she needs a good amount of time to readjust. She'll feel "special" and relieved that she will no longer have to guard her food.
I know a LOT about this bc I've kept/fed/grained my horses outside (inside, too, for the past decade) for over 26 years and they compete for food, even if they'll full!! Even now, I am graining my 3 horses under the fence with buckets, and they're placed according to how far apart they need to be to keep all of them happy. The only horse who could use a few extra pounds is my herd leader, and he always gets first dibs.