This also equates to 350 slices of pizza consumed for every 2nd! The common selection of sesame seeds on a McDonald's Big Mac bun is 178. The Big Mac is a popular sandwich at McDonald's that is made up of lettuce, cheese, pickles, "exclusive sauce," onions, two slices of beef and a slice of bread in the center. How numerous seeds (on ordinary) are on a McDonald's Big Mac bun?