A: A healthy full-grown bird begins on day one. Provide a balanced starter diet to new chicks, based on their breed traits. For chicks who will later lay eggs, select a feed that has 18 percent protein, like Purina Start & Grow Crumbles. For meat birds and mixed flocks, choose a complete feed with 20 percent protein, like Purina Flock Raiser Crumbles. Transition layer chicks onto a higher-calcium complete feed, like Purina Layena Crumbles or Pellets, when they begin laying eggs at age 18 to 20 weeks.