From what I recall (which is personally why I don't do it) - some cats can't tolerate beef (its more of a dog food - ruminant meat, not like the ole hunt for mice and quail days).
Some folks reported a long time ago problems with beef and beef mixes in kitty food. Siberia is sensitive tummy, so I personally have found the best to be a single meat source (with occasional cans of different mixes, but no beef).
Also, there has been an occasional (very occasional) bout of vomiting with Siberia. He will eat the rest of the food okay - as if nothing happened, and doesn't seem to be sick during these instances (however, he likes to lap up things kitties shouldn't lap up, and no matter how hard you try, he will find a way

)