Well, according to her, when they have it available all the time, it isn't special anymore so they only eat what they need. I know our goats certainly prefer what they can't have, merely because they can't, so it does make some sense.
@Bhubbard No, it was sweet feed, NOT minerals, I saw it myself and we talked to her about it. I breed and raise goats, so I know they can die from bloat, I wasn't recommending it, just saying that she did it and I thought it was interesting.
@Perris what do you feed your chickens, if you don't mind my asking?
On the topic of goats over eating, we had a neighbor that free-fed grain to her goat herd, as in they had full bowls of grain available to them 24/7, and they never over ate. I had never seen anyone do that before.