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.he meat of a lamb is taken from the animal between one month and one year old, with a carcase (carcass in American English) weight of between 5.5 and 30 kilograms (12 and 65 lbs). This meat generally is more tender than that from older sheep and appears more often on tables in some Western countries.