I was going to suggest LifeLine also, but was recently accused of being a shareholder or something - NOT!
Kinda surprised your guys didn't dive in - my herd couldn't get enough!
I imagine feed from the same or different mills could vary from one batch to another, as I'm sure one man's measure of a bucket of ingredients is'nt the same as anothers, freshness and sequence of ingredients added, mixing times and speeds could all have an influence on the final product!
Hope this straightens out your guys!