Chicken manure used as cattle feed. I believe this happened in the UK up until the BSE scare.

https://www.nation.co.ke/business/seedsofgold/Chicken-manure-has-more-uses-it-is-not-just-waste-/2301238-3170352-op9qe0/index.ht

From the Guardian 1999
https://www.theguardian.com/news/1999/oct/27/food.foodanddrink2

I had a fill in job on a battery farm in the 80's. The manure fell into the lower 8feet of the building and was cleaned out with a bobcat a couple of times a year.The rumour was that the final destination was as above.