You will need to determine the highest %protein these types of birds can utilize. For example, I recently raised 10 Wade Jean Marans with 8 BBW turkeys. Because of the turkeys started them all on the 28% protein turkey starter. By four weeks I could see the BBW were 3X the size of the marans, yet the food was the same!
THe marans were moved to a 16% chick starter because is is not cost effective to provide a feed that is more expensive(protein%) and they can't utilize it. I keep the BBW on turkey starter.
You'll want to consider 2 things: Will this bird grow more on a higher % protein? and How will that extra protein be provided?
Not all proteins are created equal. If you are adding to a prepared feed, I would suggest a meat based protein, like fish meal or red wigglers, or mealworms. It has all the amino acids ( complete protein) that a bird can use. If you add SBM, be sure that the feed already contains corn. (Corn plus Soy = complete protein.
I wouldn't worry about this small change in the vit/min of the total feed. Most bagged feeds have enough.