Originally Posted by alldun
I don't think it would hurt at all
Actually it could do a lot of hurt. If the foal is getting the nutrition it needs from the mare and you add the hand feeding, it could be too rich and cause scours/diarreha as the body is trying to clean out the excess minerals, etc it does not need. Also if the foal is being hand fed, it may stop nursing and the mare will stop her production of milk.
Diarreha in a new foal can result in deyhydration very quickly and death.
If you are unsure if the foal is getting enough nutrients from the mare, please have a vet experienced with neonatal issues examine the foal. There are blood tests that will specifically give you the foals status.