Hence the phrase "alleged method of toxicity" in my original post.
It's incredible how much misinformation I see passed around here daily (and have even done it myself before learning new information).. but do *usually* (remember to and appreciate the reminder to) encourage folks to use their...
My thought was the same as all the previous posters.
This link describes the alleged method of toxicity..
https://animal-world.com/can-chickens-eat-lettuce/
Many more toxic things than that are growing in my yard/pasture.
Small amounts of iceberg lettuce are not an issue IMO and experience...