Switching brands/types of feed

[Murphy212]

My 11 chicks are 10 weeks old and have been on Southern States "medicated chick start and grow" since they were hatched. I would like to change them to an unmedicated feed but am having trouble finding it in my area. I have found an unmedicated brand at Tractor Supply but the protein content is different. My understanding is that they should be on 18% protein until they switch to layer feed after 20 weeks old which is generally 16%. My chicks are destined to be layers not dinner. Not sure what the term "developer" means in chicken feeding, starter/grower and Layer make sense but "developer", not so sure.
My question is does it make any difference in brands of feed? Can you just up and switch to another brand without upsetting their digestive systems?
Have searched but can't find an answer about this.
Any help will be greatly appreciated. Please forgive me if my terminology is wrong....this is my first experience at raising chickens.
Murphy

 

[cubalaya]

southern states has non medicated chick starter and it even comes in 25 lb bags too. i use it after they have a few weeks of the medicated.