What happens if a foal doesn't drin milk?

Then I guess that means you have the responsibility of making sure that foal does get enough milk, and that means bottle-feeding it yourself.

In addition to the above answer, if the foal is old enough it would be better to feed the foal a milk re-placer from a bucket rather than a bottle. If the mare seems to be having trouble during nursing you should call an equine vet to come out and check the mare, she might have an infection that is making it painful for her to have the foal nursing and she pushes it away too soon. A lack of milk can also be caused by improper nutrition during pregnancy. This can be remedied a bit by adding alfalfa to the diet which will provide extra nutrients to the mare and allow for better milk production.