When making meatloaf, look for ground chuck at your local grocery store! Ground chuck comes specifically from the shoulder and neck muscles of a cow, whereas ground beef is made up of leftover trimmings that are too small to be sold individually. This makes chuck a bit pricier, but it’s more cohesive and will better hold a loaf shape (it’s also really fantastic for making meatballs). Ground chuck is fairly lean, but a tad fattier than ground beef labeled as “lean” or “extra lean.”