Fatal feeding the cause of mass deaths?

Saiga tatarica.A vet from London’s Royal Veterinary College believes overeating could be the reason why Kazakhstan’s critically endangered saiga antelope (Saiga tatarica) population has suffered its second mass die-off in a row.

At a critical disease workshop held recently in Kazakhstan’s capital Astana, Richard Kock rejected the original diagnosis of pasteurellosis being the cause of death, and instead concluded the animals’ own hunger and thirst post calving, and a desire to feed on rich, moisture- laden pasture, was more likely to blame.

Both the 2010 and 2011 die-offs occurred during May, and primarily involved female saiga and their offspring. An area in the region’s Zhanibek location, long recognised as principal habitat for the Ural saiga population due to its having several low lying areas of rich pasture, was the site of both mass mortalities. However a herd of approximately 4000 animals that pastured elsewhere after calving this year, remained healthy and unaffected.

“I’m not convinced after examining the evidence that the cause for this mass die-off was pasteurellosis, or any other primary bacterial or viral transmissable contagious disease for that matter. The epidemiology doesn’t fit well. I suspect this is a die-off associated with the specific location, and pasture conditions at the time,” Kock said.

As scientists have found no evidence of either poisoning or contamination of pasture grass, Kock dismissed the initial diagnosis of pasteurellosis or clostridiosis being the likely cause of death as of: ‘no coincidence, and untypical of a contagious disease’. Instead he claimed climate and pasture conditions were the contributing factors in rapid and progressive digestive disturbance for the animals, that in turn resulted in ruben dysfunction with associated problems including lung pathology and bloat. That evidence of these symptoms was widespread suggests the cause of death in many animals was due to asphyxia, while others probably succumbed to secondary bacterial infections.

Kock’s findings will prove invaluable to those involved in saiga conservation according to Gulmira Izimbergenova, project manager with the Association for the Conservation of Biodiversity of Kazakhstan.

“The research that has come out of this workshop is imperative to our understanding of the mass mortality of the saiga. The outcome is crucial in enabling us to plan to conserve this critically endangered antelope,” he said.

The head of Europe Department at Frankfurt Zoological Society, Michael Brombacher agreed.

“The government of Kazakhstan and the international partners invest a lot of money to successfully improve the conservation status of saigas. Through the mass die-offs in 2010 and 2011 we lost several thousand animals within days. Now we know the cause we can plan prevention to better protect saigas,” he said.

Migrating herds of up to 100,000 saigas once roamed the plains throughout Central Asia and Russia. Their populations declined dramatically following the collapse of the Soviet Union due to unrestricted hunting, and an increased demand for their horns for use in Chinese medicine. The species has declined by 95 per cent in recent years and is now considered critically endangered by the International Union for Conservation of Nature.

Anne Layton-Bennett