The carcasses of pigs liable to be graded in terms of the Pig Industry Act shall be graded by a Government grader at a slaughter-house in accordance with the provisions of the First Schedule in one or other of the grades there specified. Carcasses of pigs so graded shall be marked by a Government grader in accordance with the provisions of the Second Schedule, except the carcasses of pigs slaughtered for export from Zambia by a registered exporter. Carcasses may also be re-graded in certain circ