Since you're in Texas, my comments should be relevant...
First of all, cattle bought at sale barn in all probability don't have any health or medical history or documentation to go with them...caveat emptor. As such,
I'd definitely de-worm all of them. Then, I'd give them Blackleg and Respiratory vaccinations. If any are feeling listless, "depressed", or have runny feces, I'd check with your Vet and do what he/she recommends for any antibiotics to innoculate them with. "Shipping Fever" is also another event associated with animals from sale barns and other unclean places.
If your Vet says nothing is needed, I'd consult with another Vet.
It is not uncommon for cattle people selling at the sale barn to bring cattle with no records and/or a comprehensive medical protocol. They are selling "meat" at sale barn, nothing else...
Our policy is that IF we buy an animal from another ranch that doesn't have PROOF of vaccinations and/or de-worming, then we ASSUME nothing has been done. In any event, we always de-worm and quarantine any new arrivals for week or so.
Hope this info helps...