Attach a lead and use it as a combination lead rope, chest rope and butt rope to teach the foal to lead. Two sessions per day. Include lifting each leg so you can look at the bottom of the hoof. Lead the foal with only the halter with the dam confined nearby. Now the foal's training progresses into an overall ground training program which over the next months includes in-hand maneuvers, obstacles, tying, and trailer loading.
Reflexes are automatic, unconscious responses to a certain stimuli.
Natural selection favored horses who had a high self-preservation aptitude. Part of this included finding milk early. The suckling reflex is a strong instinct that the foal uses to find and secure the teat, thereby obtaining nutrition. Often the dam stimulates the newborn foal to suckle by nibbling the foal along the back or on the rump or nipping his hind legs. This tends to make him extend his neck and use his mouth to search for food.