I agree, feed whatever you want. What I'm taking exception to here is singling out Purina for using vitamin additives from China. Also objecting to people implying that Purina is adding anything other than trace ingredients that were sourced in China. If you read thru this thread, it sounds like Purina is using chickens raised in China rather than just trace ingredients.
Sure, I know the Purina Pro Club is a marketing ploy. But they have donated over $165,000 to the Golden Retriever Club of America's health research foundation over the past 9 years. That means something to me. Haven't seen any of the other manufacturers, large or small, doing the same.