Merrick Pet Food

Ok here's a link describing how during the Mad Cow scare, a dozen or so cows with nerve disorders were taken by Hereford ByProducts, which is owned by Merrick. According to this, the rendering plant is located in the same facility as Merrick Foods. This is from the book "Food Pets Die For".
http://www.newsagepress.com/media/foodpetsdiefor/book_text/MadCowDisease.pdf