What kinds of vitamins or nutrients are best for Boas?

I fed my boa frozen rats that I get from Petsmart and from a locally owned shop. Recently I heard that Petsmart sprays its frozen rats with a suppliment which is good or better for my snake.

I was wondering if anyone else had heard this or if any experts who might know if boas need any other nutrients that they maybe missing out on by having such a limited diet as opposed to in the wild where their diet would be more diverse.