How finished should the reining be before cattle are introduced?

The reining does not need to be finished to a competition standard before cattle are introduced for the first time, but specific foundational responses need to be reliably confirmed before the horse is asked to do anything more than look at and follow cattle in a low-pressure environment. The minimum foundation for beginning systematic cattle work — work that makes specific physical demands on the horse — includes a soft, willing stop that the horse takes from the seat cue without significant rein, a rollback that is correct in its mechanics if not yet fast or polished, circles that show genuine rate control between large fast and small slow, independent hip and shoulder movement from leg pressure, and a lead change that is clean in front and reasonably clean behind even if the timing is not yet competition-precise. Those responses do not need to be at their peak performance level, but they need to be reliable enough that the cattle environment's additional excitement and distraction does not eliminate them entirely. A horse that has those responses at seventy percent of where they will eventually be is ready to begin systematic cattle introduction; a horse that has them at fifty percent will find that the cattle environment reduces them to thirty percent, which is not enough to work cattle correctly or safely. The practical standard many trainers use is the ability to execute the basic reining maneuvers correctly in a new or mildly distracting environment — if those responses hold under general environmental pressure, they will hold well enough under cattle pressure for the early stages of cattle training to be productive.