switching from non med. feed to med. feed ?!

[emjay]

So usually i put chicks on med. feed from day one. this year, silly me bought four chicks too from feed store, they had been vaccinated, so advised against med. feed.
None of the chicks are on the ground yet, but if not sold soon will be going to the barn.
Can I switch them to med. feed then , or is it pointless at this point?
I know some people who never use med. and dont have problems. as well, last year I had one chick who got cocci, and had been on the med. feed.
any suggestions on this, to switch to med . ot to not, and should i introduce it slowly to not upset their digestibe system.
thanks

 

[Komaki]

Thats not enough info for me to help, BUT! If you are selling them, where are you state wise (because I happen to be an addi.........need more. I'm in Florida and if it is possible I could help that way.

 

[emjay]

I am in Canada