Totally up to you, but I never have with this recipe. My oldest does. He likes a shiny golden top to his bread rolls. An egg yolk will help the rolls to brown, but you really don't need any help with these rolls browning, as the oven temp will do just fine on its own; in fact, you may have to cover with foil to avoid too much browning. Egg white will give the shine. You can even brush with melted butter after baking for added flavor and a bit of shine.