Lamb, hogget, and mutton (UK, India, South Africa, Canada, New Zealand and Australia) are terms for the meat of domestic sheep (species Ovis aries) at different ages.A sheep in its first year is called a lamb, and its meat is also called lamb.The meat of a juvenile sheep older than one year is hogget; outside North America this is also a term for the living animal.ounger lambs are smaller and more tender. Mutton is meat from a sheep over two years old, and has less tender flesh. In general, the darker the colour, the older the animal. Baby lamb meat will be pale pink, while regular lamb is pinkish-red.