Ah! As one who has lived with cow manure pretty much from birth, let me make a suggestion. Fresh manure isn’t the best, because it’s pretty acidic. For that reason, I wear special oil-treated boots in the corrals. Fresh manure will eat ordinary ones up.
The best for gardening is what I think of as “depleted manure”; manure that has some age to it. The absolute best is manure that has been stomped in with hay and mud in some farmer’s barn or “loafing shed”, but a barn or shed that is no longer in current use. Cut that into the soil of a garden and it will make berries or vegetables pop out of the ground, rich and colorful and flavorful.
Horse manure, I don’t like. Can’t get past the odor for some reason, and those “biscuits” don’t mix well with soil anyway. To each his own.
Man, I truly do hope you get your cow one of these days. But I wouldn’t count on it and the horse getting along particularly well. Some horses have a tendency to bully cows, and ponies are the worst of all in that regard. (It’s the biting)