Our puppy came home on the ALS 30:20 formula, but I researched the regular puppy formula, LB puppy, and the Sport puppy formulas too, and realized that the formulas are actually very similar. The LB puppy has a 30:18 protein to fat ratio and more fiber, and a few other small differences in percentages on the guaranteed analysis. There are a few ingredient differences as well, if you compare, but overall pretty similar:
Purina Pro Plan Sport Performance 30/20 formula high protein dry dog food is fine-tuned nutrition to promote strength & endurance in hardworking and highly active dogs
www.purina.com
Purina Pro Plan large breed dry puppy food with chicken and rice offers nutrition for the development of puppies weighing over 50 pounds at maturity. Try it today.
www.purina.com
I would think if you're going from the same protein (ex: chicken to chicken), you could probably go ahead and expedite the transition without too much stomach upset, especially since it sounds like you've already started the process so it wouldn't be completely new.
Someone else with more experience can probably weigh in better. If it were my dog, though, I'd feel pretty comfortable finishing this particular transition without buying more puppy food. Especially at the price of food. I ran out one day (waiting on my 50 lb bag that was shipped) and bought the 6 lb bag to get by. It was $20! Worst part is, my shipment arrived the second I served dinner out of that darn 6 lb bag
