Ten female blackbucks, out of which five were reported to be pregnant, were among the total 16 blacbucks which died in Kota on Thursday morning, they said.
"The blackbucks might have died due to pneumonia but the postmortem report is still awaited," Divisional Forest Officer Anurag Bhardwaj said, adding that there was chances that the antelopes had lung infection which resulted in their deaths.
Akhilesh Pandey, veterinary physician of Kota zoo, claimed that the blackbucks could have died due to cold that led to lungs infection.
Kota zoo has a total of 21 blackbucks out of which 16 have died and two other are undergoing treatment.
Pandey admitted that the zoo officials were unaware that the blackbucks were suffering from any disease.
Meanwhile, a wildlife activist expressed concern over the death of the blackbucks, a scheduled 1 animal under the Wildlife Protection Act 1972, and blamed zoo authorities for their carelessness, calling it a "black day for wild life in Rajasthan".