Corned beef is derived from cattle (beef), not from pigs (pork). Also, don't mistake 'corned beef' for 'corn-fed beef'. 'Corned beef' is a brine cured cut of beef, whereas 'corn-fed beef' is cattle...
There is no such thing. Pork comes from pigs and beef is cow meat, two entirely different animals. It is, however, possible that a badly punctuated recipe meant to refer to a mixture of ground pork...