If you're going to try the life of a warmongering Horse lord
you'll need at least 3xclan members with breeder to get them breeding regularly. 5+ for increased frequency. 5 clan members with breeder tends to give a high chance of the rare horses breeding more often. Its only 1% chance for 1 perk, but it stacks. Even though it says 1% chance they do still breed, but its usually the low level horses like the sumpter horse at first. The scout perk to tame wild horses is also good to have if you're goong to play as a horse lord