I consider everything as a treat unless offered specifically to boost something that's lacking in their normal feed; I live in Panama, and their standards for animal feed are inferior to most published norms. It's a delicate balancing act to boost some things, without compromising the overall protein. I'm forced by lack of availability at my feed store (and my budget) to feed rice and split peas to bolster their methionine & lysine levels and ground up dry cat food to bolster the overall protein level as the standard feed at the store is sorely lacking. There's two main suppliers of feed, that provides for the four feed stores; it's pretty much a monopoly. They won't do custom orders, and certainly not for someone that only needs 2-40kg bags a year.
That said, my definition for treats would be things like watermelon, cucumber, iceberg lettuce, popcorn, scratch, corn, oatmeal, raisins and probably a lot of things that I just don't remember right now

Treats aren't bad, but if you can watch what you treat, and when you treat it can make a world of difference in your flock and their health. Fruit can be a very beneficial treat, not so much for nutrition, but for hot days when they really don't want to eat, drink, or move much... I've yet to meet a chicken (or quail) that didn't love, and wouldn't run to get some watermelon. It's an excellent source of WATER and electrolytes.