Quote:
Since I'm looking at the livestock, it helps me know what to plant in my pasture. Since the livestock I'm looking at are all ruminants eating grass, I try to apply the grass issues to the ruminants.
Since chickens are mono-gastric, and omnivores, I often think in terms of what works for people and other mono-gastric, omnivorous animals can often translate over to the chicken. Now, of course, there are some differences in the digestion system - more in some birds than others - but until I find something to convince me to the contrary, I treat a chicken as the mono-gastric omnivore that it is!
One thing that I think you have to consider is that ruminants left to feed as they were designed have grass/browse as their main nutrient source and, thus, eat much more of it than an omnivore. It stands to reason that the omnivore that has a choice can find other sources to feed from if a particular grass source has become toxic.
I think that's what you see when folks say their chickens "know what's good for them". A little taste and they're off to something better - IF THERE IS SOMETHING BETTER AVAILABLE.
Most of us offer our chickens a variety - including the freedom to forage at one degree or another. In that kind of scenario I don't think there is a worry with them eating too much of any food substance that is harmful.