Chickens (contrary to popular belief) don’t produce lactase, the enzyme needed to break down lactose. While a bit of yogurt likely won’t kill them, dairy can cause digestive upset, and nutrient absorption issues if given regularly. I know this is contrary to what is on the internet and touted by chicken keepers- at first I thought 'sure, okay- no birds can have milk products- I learned it in school for 8 years, but I guess chickens are different, but i doubt it' ... I went back in my textbooks, and consulted a specialty nutritionist who works exclusively with poultry from way back in uni, and they assured me I am correct- and told me it started on a goat farm with a small flock back in the 1970's when people started to understand that probiotics were good for humans. So no yogurt for my birds. Although they do like it!
And to the person who said maybe they are made in china- nope, not according to the label. They just wont touch anything, not even the grain mixes with insects. So I just threw it on the ground and let it sprout and the bugs got devoured by the hermit crabs. The chickens ate what sprouted.