Last week when I was at Tractor Supply, I picked up a bag of DuMOR Chick Starter 24%. I was reading the ingredient tags and some had bags with animal protein products listed as an ingredient and some that did not. The one that I bought had animal protein listed and was milled in May. The bags without the animal protein was milled in April. Has anyone noticed this before? Why might this be? Coming possibly from different milling sites?