LAKHIMPUR KHERI: Dudhwa Tiger Reserve authorities have pinned their hopes on Indian Veterinary Research Institute (IVRI), Bareilly to ascertain the exact cause behind the death of 25 vultures, whose carcasses were recovered from a field under Bhira range of the Dudhwa buffer zone, officials said on Thursday.The carcasses of vultures, a protected species under the Wildlife Protection Act and categorised under critically endangered species of birds, were recovered on Tuesday.Dudhwa buffer zone, deputy director Kirti Chaudhary said that 25 vultures (presumed to be mostly of Himalayan Griffin species) were found dead, lying in an agricultural field in Semarai village under the Dudhwa buffer zone.She added that five other vultures were found in an unconscious state in the field and were immediately provided treatment before being released after they were found fit to fly.Chaudhary told PTI that the carcasses of a few dogs were also recovered from the same field at some distance away. She added that vultures were suspected to have died after consuming those carcasses.She said that a panel of veterinary doctors comprising Dr Daya Shankar from Dudhwa, Dr Ankur and Dr Rajendra Singh carried out the postmortem of 23 dead vultures while the carcasses of two of them were sent to IVRI, Bareilly along with the viscera of 23 vultures for further investigation and analysis as per instructions from DTR field director and chief conservator of forest Dr H Rajamohan.However, the postmortem failed to pinpoint the exact nature of poison found in the carcasses, though it was found that the vultures died after consuming the remains of dog carcasses recovered from the same spot.Dr Daya Shankar, a member of the postmortem panel, told PTI that prima facie, the postmortem revealed that the carcasses of dogs had some poisonous substance.