you can use bones from just about any animal-beef, veal, lamb, bison or buffalo, venison, chicken, duck, goose, turkey, or pork. get a variety of bones-ask for marrow bones, oxtail, and "soup bones." make sure you include some larger bones like knuckles, or feet (like chicken feet), which will contain more cartilage, and therefore more collagen.
roast your bones for one hour in an oven set to 350 degrees first, for a richer flavor and color.
Paul Jaminet of The Perfect Health Diet says you can reuse bones to make multiple batches of broth until the bones go soft (make sure you use fresh vegetables, herbs, and spices each time, though.)