According to zoo officials here, the animal ran out of its enclosure resulting in internal injury and pulmonary haemorrhage last night.
A post-mortem was conducted by a team of veterinarians today.
The animal was among the pair of white bucks which were brought here from Delhi Zoo two years ago.
At present, there are three white bucks--one male and two female-at the zoo here.
Since the animal is very sensitive and can die out of fright in case of any danger, white bucks are being kept in separate enclosures, zoo sources added.