It's actually a good idea for your farm to be separate from your 'main' base.
That way your farm is less likely to be raided as no raids/damage will take place
if you're not there. Don't spend a lot of time at your farms; harvest/plant,
butcher some boars and feed them to breed. When they squeal loudly; they've
just birthed a piglet. You can leave then if you wish; whether the piglets grow
while you're not there or achieve full growth when you return is irrelevant;
you'll find boars not piglets.

To be really safe from raids at your farm visit it just after any raid; you have
about 40? minutes in real time before the chance of another raid.