So I decided to ask Costco and see what was up. Here’s round one of the stonewalling:
We appreciate you taking the time to email Costco Wholesale.
We are unable to provide vendor or manufacturer contact information for our Kirkland Signature products.
If you have general questions regarding one of our private label products, please reply to this e-mail and we will be happy to assist you.
Member Service Center
Costco Wholesale Corporation
My bet is they refuse to disclose this due to manufacturing agreements where Name Brand Company X sells to them and to Sam’s Club without revealing to either that they’re providing the same stuff.
We’ll see if my next series of general questions gets answered. Perhaps if they can’t tell me who or where, they can tell me how they’re ensuring that it’s not contaminated or a reject batch from Name Brand Company X.
Based on this, fingers point to Abbott Nutrition, makers of Similac. But no conclusive statements yet.