TAIPEI - A giant panda, Yuan Yuan, has failed to conceive after undergoing artificial insemination on March 17 with sperm from male Tuan Tuan, Taipei Zoo has announced.

The zoo said that the ultrasound and urinalysis and a previous blood test on the bear indicate no sign of pregnancy.

In addition, while zoo staff have said that the panda had exhibited behaviors associated with pregnancy, such as a loss of appetite, lethargy and reduced defecation, her symptoms began to fade on July 15, 119 days after she had been inseminated.

Yuan Yuan will return to her public pen after a few day's rest, according to the zoo.

Giant pandas have a low fertility rate because they are sexually inactive. Female pandas can only become pregnant once a year and have litters of two cubs at most. The gestation period usually lasts from 120 to 150 days.

The pair, Tuan Tuan and Yuan Yuan, were given as a goodwill gift to Taiwan by the Chinese mainland in 2008, both were born in 2004.

They had their first and only cub so far, Yuan Zai, on July 6, 2013, also by artificial insemination.