Mazuri and Harlan spend quite a bit of time, money and research formulating these diets to provide everything a rat needs.
If you notice, they also have at least a dozen different formulas. As long as you keep the food within the "guidlines" of what rats thrive on, then you should be fine. Rats are omnivores, they're not eating a specific lab block out in the wild, but getting mixed grains, veggies, meats, insects, etc.

Another thing with poultry feed, make sure you do NOT get medicated (saw a bag of it when I was picking up bedding and duck food the other day).