Feed is by far the biggest expense, but it takes money to start a backyard flock, house it, feed it, provide it with fresh straw or wood chips for bedding and protect it from predators. The average hen's egg production peaks at one year and declines until she stops producing altogether at four or five years. At that point, the rancher can continue to house and feed the non-laying hen (recouping none of those costs via eggs) or slaughter her for chicken soup. Unless the backyard rancher is capable of this, that's another cost.