I've always had excellent dairy products from Aldi. There's a dairy code on all milk sold in the US. It's a code like xx-xxx (29-162 is Roberts/Hiland in KC) that's printed on the container. These codes are also on butter, cottage cheese and other fresh dairy products.
In the KC area Walmart's Great Value and Target's Market Pantry (both private label) come from the Hiland dairy in KC. Aldi milk in the KC area comes from Dean's Foods dairy. They highlight "Dairy Pure" products. No antibiotics, no rBST. I think Hiland does the same thing without the catchy marketing slogan.
Here's the website to put in the code from your dairy containers:
http://whereismymilkfrom.com/