2 calves need wormed?

I think they do, these are my first. Had a calf last year, but the worming was all take care of by the person who sold her to me , these have had nothing done.

Do I need to worm them, one's 5 months other is 4 months. their eating feed and plenty of grass. They look like they have pot bellies for sure LOL so I think their getting fed good. But do I need to worm them or will they be fine with out it.

one is for slaughter, other is for breeding. I'd prefer nothing chemical in either of them, but the one is along way from slaughtering so it probably won't be in his system for long.?

any ideas?

kathy