Using one formula to the next.

M
Just out of curiousity, I received a bunch of samples from Gerber, Enfamil and Similac. What happens if I was to use the entire can of Gerber, then the entire can of Enfamil after, then tried the entire can of similac? (With the assumption that my baby takes and likes all 3) Is it not good to mix the different brands of formula?