My runners, who free-range during the day all year, eat all-flock. There is a dish of oyster shell available to them, the chickens and geese. Of course, because I spoil everybody, they all also get grapes and any produce that is less than desirable for me to eat. A bit of wilty salad greens draws a crowd every time. And, on the coldest days, I throw a handful or two of scratch grains.
But I try not to overdo with the treats -- just like I try to limit myself to only one or two cookies!