Lukullus Single Meat Beef

Why do so many of these 'single meat' products contain chicken fat or other chicken by products? My dog is on an elimination diet so I'm checking all ingredients as she can't have any chicken. It's difficult to find an actual chicken-free dry food for a large dog!

Good product, but the downside is they've removed the zip from the packaging, so it's hard to open and, above all, to keep it closed. The previous packaging was much better.