What kind of feed can my senior horses eat?

I have been feeding my 2 senior horses Nutrena Senior Feed, not the John Lyon signature brand. It is $14.49/bag at my local feed store and i go through 1 to 1 & 1/2 bags a week. It is getting pretty costly. Is there other brands that are just as good for senior horses that won't make them have digestive problems? It also must be able to get wetted down, because I have to make it into a bran mash as they have choke syndrome. The reason I have been using Nutrena Senior so long is because it has rice bran and beet pulp in it, and as far as I know, no other senior feed does that. If it helps in your research, i live in minnesota, so please don't give me a name of something that is only available in machusetts or whatever state you live in! THanks!