A Murdoch University study has examined the frequency and on-farm risk factors for diarrhoea in meat lamb flocks.
Dr Joshua Sweeny from the School of Veterinary and Biomedical Sciences said faecal soiling of breech fleece was a significant economic and welfare problem for sheep enterprises worldwide one linked to increased carcase contamination by enteric microbes, which can cause meat spoilage and human food poisoning.
Of those surveyed in Western Australia, evidence of recent diarrhoea was reported on 64.8 per cent of farms, with an average of 6.9 per cent of lambs affected per farm.
Farms located in areas with higher rainfall showed increased rates of diarrhoea. We traced this back to the drinking water source, since lamb flocks supplied with dam water were 117 times more likely to have observed diarrhoea or breech fleece soiling, Dr Sweeny said.
Dr Sweeny said this could be due to increased run-off contaminants compared to lambs drinking water from a bore or scheme source.
Faecal material, fertilisers and pesticide residues can be washed from pastures into open sources following moderate or heavy rainfall, whereas bore and scheme water is better protected, Dr Sweeny said.
Dr Sweeny said a better understanding of risk factors and causes would lead to better management of outbreaks.
Producers tended to increase anthelmintic treatments for parasites when dealing with diarrhoea in a flock, even though parasites are not necessarily the cause of the outbreak. This sort of overuse is contributing to increased resistance in worm populations.
Producers need access to cost-effective diagnostic tools so they can better understand the cause of an outbreak and then deal with it in the right manner.
According to 2010 statistics, 7100 farms in WA ran a sheep enterprise (wool or meat production), accounting for approximately 14.7 million sheep.
Dr Sweenys study included data from 139 (roughly ten per cent) of the 1316 farms with a specialised lamb meat enterprise that sent lambs for slaughter at commercial abattoirs.
The full paper can be found in The Veterinary Journal 192 (2012) 503-510.
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More information: www.sciencedirect.com/science/article/pii/S1090023311002565