Originally posted by Estyn:

As for food consumption, the AI will consume food even if you're out of range it seems. If this happens, the boars don't seem to breed, even though they consume the food. This appears to be a bug. As a workaround, I limit the amount of carrots I feed the boars, depending on how long I plan on sticking near the base that session.

I had opposite experience.
My boar pen is in remote place where I need to go through portal, I left them some berries when there were 3, when I checked back some time later, there were 6.