Given the new homes, many streets are essentially abandoned atm. This means they never load.
When I attempt to nibble pigs that should be feeding off of the trees, they are starving and will not give meat. If I stay around for a few minutes, so that they wander near a tree, and feed, they are once again nibbleable (is this a word?).
Essentially, pigs are starving because they have a wall clock timer that says "have I been fed recently". But, if their street does not load, or is not active, or whatever, they don't auto-feed.