What is Mutton? Mutton is meat from a sheep that is older than 1 year, ideally 2-3 years old. It is an intense red color and contains a considerable amount of fat. Its flavor is stronger, and some people do prefer this more "gamey" taste to it. Great for spicing up that meatloaf or making juicy lamb patties. Our lambs have not been fed any grain, so try it to taste the difference!