you can definitely use many of the heavy breeds as great dual-purpose birds (eggs and meat). I know that Orpingtons, Marans, and Cochins are all supposed to be good meat birds and if you keep some around they will lay for you as well. You can keep a bunch of hens for laying and a rooster or two then let the girls hatch now and again and eat the surplus boys (or all of the extras). That is the old-fashioned way to do it. These heritage breeds grow much more slowly and take about twice as long 12-18 weeks to be ready for slaughter, but they are healthier, more flavorful, and more self sufficient than the cornish cross "meaties."