Following a marked increase in cases of suspected cattle botulism, Defra is warning farmers of the dangers posed by spreading poultry litter on pasture which is grazed by livestock or made into forage. From 1997 to 2002, the Veterinary Laboratories Agency investigated an average of four botulism incidents each year but 20 potential botulism outbreaks were investigated last year. The VLA said there was evidence that litter from deep-litter broiler houses was the cause of disease in many of the recent outbreaks.Investigations have revealed that affected cattle had direct or indirect contact with poultry litter when it was used as bedding for housed animals, as a fertiliser on grazing land and when it was stored in or adjacent to fields where cattle were grazing. Cases have also occurred when cattle were fed silage from fields fertilised with poultry litter.Losses have varied from a death of a single animal to the loss of up to 80 per cent of the herd and when botulism is suspected in food animals the Food Standards Agency require that meat and milk are withheld from entering the food chain for two weeks after diagnosis of the last clinical case within the herd.Alick Simmons, head of Defra's veterinary epidemiology and zoonosis division, said that while there were benefits from recycling of poultry litter as fertiliser on farmland, farmers had to ensure that they were complying with the law.Spreading poultry litter on land which contained carcases or parts of carcases was illegal and put at risk the health of their cattle and possibly that of their neighbours, he added.Defra and the VLA have recommended the following measures to reduce the risk of disease and economic loss. • Poultry carcases and carcase material must be collected and disposed of in accordance with the Animal By-Products Regulations 2003, ie by rendering or incineration.
• Poultry litter should not be used as fertiliser on the surface of grazing land or land used for conserving hay or silage.
• Poultry litter that is recycled into agricultural land must not contain poultry carcases or carcase material.
• Poultry litter should not be used as bedding material for livestock.
• Poultry litter should be disposed of by incineration, deep ploughing or burial.
• Facilities or equipment used for poultry litter transport and disposal should not be used for storing, mixing or distributing feeding stuffs.
• Access of scavenging domestic and wild animals, birds or livestock to stored litter should be prevented.
• Good personal hygiene precautions should be observed when handling litter because poultry litter may contain a range of human pathogens.While Defra point to broiler litter as being the main cause of the disease in the cases so far investigated, there is no specific advice as to the risk from the droppings and litter removed from free range houses. It is thought, however, that unless the material contains the remains of dead birds, the risk will be extremely low.It has been suggested by one industry expert that the rise in incidence from broiler litter may be the result of the banning of growth promoters which has led to the presence of more Clostridia in the litter.
by the Ranger vets at Crowshall Veterinary Services• Botulism is a toxic poisoning of animals associated with eating material contaminated with botulinum toxin, or on occasions possibly eating material contaminated with the organism that produces the toxin, Clostridium botulinum.
• The symptoms of botulism in man and animals are progressive paralysis and eventual death.
• The condition is extremely rare in poultry and where it has occurred it has been associated with birds gaining access to rotting carcases, or even more rarely, eating maggots that may have been feeding on rotting carcases.
• Occasionally, at this time of year, cases can occur in small groups of wild or ornamental waterfowl feeding in ponds or stagnant water, especially when water levels fall and such birds get access to decaying material on the waterbed.
• Most housed and free range layers are very unlikely to suffer botulism as it would be rare for them to meet the organism or the toxin.
• The risk to poultry and other animals is greatly diminished by ensuring that the carcases of any birds dying on site (plus any wild birds or vermin carcases) are removed from the house or range as soon after death as possible, and are disposed of promptly and correctly.