National Zoo reveals cause of panda cub death

WASHINGTON (AP) - National Zoo scientists have determined what killed a 6-day-old giant panda cub and are preparing to announce their findings.
 
   The zoo will disclose the cause of death at a news conference Thursday morning. The zoo will also offer a glimpse of panda mother Mei Xiang in her yard. Her behavior has slowly returned to normal after the cub's death.
 
   The cub, believed to be female, was born Sept. 16. Zoo officials and panda fans were devastated by its death less than a week later. The birth was a surprise because it hadn't been clear whether Mei Xiang was still fertile.
 
   Panda cubs are born hairless and helpless, about the size of a stick of butter.
 
   A preliminary necropsy revealed the cub had liver abnormalities and fluid in its abdomen.