The use by dates on raw meats are for quality controls only. There is no requirement by U.S.D.A. for expiraton dates. Only Re-refrigerated, cooked potentially hazardous foods must be date marked. When kept at 41 degrees, a cooked brisket may be re-refrigerated for 7 days. At 45 degrees, the same brisket may only be kept for 4 days.
Crovac packaging helps reduce oxygen, which sustains shelf life.