How do I know if my 3 week old foal is getting enough milk from the mare and how soon can I feed it?

If the foal looks healthy, bright and active, then it is probably getting adequate nutrition.

If a foal is not getting enough, you will notice a lower body condition (less than 4 on a scale of 1 to 9), plus you may see the foal continually trying to nurse. However, remember that a foal normally nurses several times per hour. A typical foal will nurse, maybe play some and then nap.  Upon waking, the foal will stretch, then either interact …