I haven't had great success with the search engine here but you
should give it a try.
Anyway, this is a very recent topic:
Sugar Beets
If you scroll down you can see my response. IMO you're asking the wrong question... A better question might be:
What can
I feed a pig eat through the growing season (May - October), as part of a balanced omnivore diet?
Wouldn't it be easier for the pig to forage than for you to have to feed it?
Maybe the question will lead to an
answer that has a sugar beet component, maybe not.