Beef packer margins fell $68/head last week and marked the third straight week of declines to end near -$220, which is back among the worst margins in the past decade. The culprit for weaker margins was an $6/cwt pullback in the Choice cutout and broader beef markets while fed cattle prices rallied to new all-time highs. Packers were relatively aggressive buying cattle for 1-14-day delivery last week, which could reduce spot purchases this week and give cattle markets an opportunity to decline. Such a move would improve margins slightly, but packers are staring at an outlook ...