Ammonia concentration poses health risk to sheep
Every year, Australian sheep producers export millions of live sheep to markets in the Middle East. But sheep producers and the public are concerned that concentrations of ammonia on board ships may put sheep at increased risk of disease. Now findings published in the Journal of Animal Science by a team of Australian scientists may help improve sheep health and welfare during live shipments.
Under conditions designed to simulate ammonia concentrations on live-animal export ships, castrated male sheep showed decreased weight gain and increased bacterial colonization of the lungs. The sheep also ate less and had increased inflammation of their nasal passages.
"Together these findings are evidence of an adverse effect of ammonia on the welfare of the sheep during simulated live-animal export shipments," said Clive Phillips, study co-author and professor of animal welfare at the University of Queensland, in an interview.
This study could help sheep producers keep their shipments healthy during the long trip to the Middle East. In the past, shipments of sheep from Australia have been rejected because of cases of diseases like scabby mouth and pustular dermatitis. Phillips said that even though those diseases are not known to be associated with increased ammonia concentrations, sheep may be at risk because ammonia can stress the tissues of the nose and mouth where these viruses may attack.
"Reducing ammonia on live export shipments should be a priority for the exporters, and the producers should require their sheep to be transported in as good conditions as possible," said Phillips. "Apart from the damaging effects on sheep, ammonia is unpleasant for workers and they may avoid working in such areas."
Phillips said there are several ways to decreased ammonia concentrations in live-animal shipments. Because ammonia in shipments primarily comes from the sheep urine, additives to either the feed or floor could be used to inhibit the chemical reactions that release the ammonia. It would also help to remove sheep manure regularly and increase ventilation.
"Reducing stocking density is a third option, but a costly one," Phillips said.
Phillips is also interested on the effects on ammonia concentration on live cattle shipments.
This study is titled "Physiological and behavioral responses of sheep to gaseous ammonia" by C. J. C. Phillips, M. K. Pines, M. Latter, T. Muller, J. C. Petherick, S. T. Norman, and J. B. Gaughan. It can be read in full at jas.fass.org.