Complex sentence: In 2009 the annual chicken population in factory farms was estimated at 50 billion, with 6 billion raised in the European Union, over 9 billion raised in the United States and more than 7 billion in China.
Split into simpler sentences: In 2009 the annual chicken population in factory farms was estimated at 50 billion. With 6 billion raised in the European Union, over 9 billion raised in the United States and more than 7 billion in China.