[tptacek]

The numbers I got were more like 9%.

You can also go to specific chains and look up their sourcing; Wendys sources from "steers and heifers", but all much younger than the average dairy cow cull age.

It's not that I have a high opinion of fast food beef. I just think it's unlikely that they could come close to meeting demand by sourcing from culled cows.

[jcampbell1]

Your 9% number is impossible as at least 10% comes from purely beef production. 25% of ground beef is old cow meat, and it isn’t sold at grocery store meat sections. It ends up in processed foods and fast food. It is legally beef, but that is about all you can say about it.

[tptacek]

Look, I honestly don't care --- I actually think it's laudable to put less commercially desirable meat to use, in the same way I think it's a good thing to use transglutaminase to stitch trim and offcuts into chicken nuggets --- but I can't find a single source that suggests culled dairy cows are a significant input to fast food. I can find direct statements from chains that preclude it. I've concluded that it's just not the case. We don't have to agree, but if you've got a source, I'll read it.