Why does a hen who used to lay eggs now crows like a rooster?

There have been cases of hermaphoditism in poultry, that is one bird that has both male and female organs. How the bird looks and acts is determined by which organs are dominate at that time.

Here is a facinating link.

http://www.ncbi.nlm.nih.gov/pubmed/8257394?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DiscoveryPanel.Pubmed_Discovery_RA