Backyard Bias and the Botulism Risk

It gives me great pleasure to post a guest blog from Andy Cawthray of Chickenstreet.  I have enjoyed Andy’s articles on both the Guardian blog and his own blog “The Chickenstreet”. I have a lot of respect for Andy’s experience in the world of poultry and I think he raises some very valid points here.


Towards the end of last year there was a flurry of media activity regarding a report written in 2010 on the risks to the poultry industry that the inexperienced backyard chicken keeper presents. I was quoted in The Guardian as having said something along the lines of “it’s not the risk the backyarder presents the industry but the other way around”, and whilst that sound bite attracted comments of support it does seem a little bit glib and throw away.

My reasons were not in response to the RVA report but in fact related to another piece of news that came out on the same day which seemed to slip under the radar. This story however wouldn’t provide the same level of sensationalism as so was stashed away in the industry reports. It related to use of broiler house litter on agricultural land and the botulism risk it presents to sheep and cattle.

I’m a gardener and vegetable grower and whether it’s a truism or not I’ve always been of the understanding that spreading poultry manure (litter) directly on to plants is a no-no as its too strong and risks burning the plants, and so I compost it for at least 6 months. Most folks who garden or grow their own also compost their green waste, it is after all not waste but stacked full of useful nutrients that have come from the soil and so can be returned to the soil.

Those of us who keep chickens also know that adding poultry litter to the compost heap not only helps accelerate the decomposition of the waste but can add significantly to the end product. It seems a sensible way to recycle both the green waste and poultry litter into something useful, and let’s face it poultry can produce a lot of waste.

The volume though is nothing compare with what would be produced on an industrial scale so what happens to that waste? Focusing in on broiler litter it would appear that up until recently the litter could be used as animal bedding! Now if you have never visited a broiler unit then might not be aware of the levels of stock and stock density in such places, and so you may not be aware that within the 1000’s of birds being reared it is quite possible that one or two individuals may die for whatever reason and effectively be trampled into the litter and go unnoticed. It’s also well documented that cattle and sheep exposed to broiler litter have an increased risk of contracting botulism if that litter contains decomposing poultry.

Checking the AHVLA quarterly report on potential food safety incidents January to March 2012 confirms 7 incidents of botulism were identified. Of these, 4 were directly attributed to the use of broiler litter as cattle bedding which resulted in a total of 270 cattle being exposed to a botulism risk and 11 cattle dying as a result. Aside from the fact that using one animals soiled litter as bedding for another seems most odd it is also alarming that this should occur given that DEFRA confirmed in 2011 that poultry litter is a category 2 animal by-product, and that the use of it as bedding for other animals is not an approved disposal method. Anyone who does is at “risk of committing an offence under the Animal Welfare Act (England) 2006 if animals suffer unnecessarily or are caused harm as a direct consequence of such action.” It is in fact now also an illegal practice under the Animal By-Products (Enforcement) Regulations 2011.

Despite this legislation the use of poultry litter as bedding for cattle is obviously still a problem today as the AHVLA felt necessary to reiterate the point that poultry litter should not be used as animal bedding in their information note published at the end of October 2012.

Green WasteThe waste though still needs to be dealt with so what is the current guidance? Poultry litter can be applied directly to farmland in an unprocessed state as this is considered “low risk”.

There are some restrictions though and if the land is pasture to be used for grazing then it cannot be grazed for 3 weeks after application, nor should it be cropped for feeding during that time period. It can however be cut for hay or silage production during that time.
So what of the other 3 incidents of botulism during that first quarter of 2012? These involved the exposure of 280 cattle of which 12 cattle were confirmed as having botulism and 9 subsequently died.

The root cause of each incident could not be pinpointed but it was suspected that the first was as a result of the cattle consuming a bale of hay containing a poultry carcass. In the second incident the AHVLA believed the source to be a carcass in a bale of silage that had been cut from a field adjoining a poultry unit. And in the third incident the AHVLA suspected the infection was as a consequence of the herd being “turned into a field where wash water from a broiler house had recently been sprayed and the field was also adjacent to arable fields where poultry litter had recently been spread”.

Bear in mind these are only the known reported food safety incidents, it is distinctly plausible there are a number more that go unnoticed or unresolved. But the same measure it would be equally sensationalist of me to declare a major concern over such a relatively small number of reported incidents when there are many industrial units that follow procedure in repeatedly checking broiler houses for carcasses as well as repeatedly screening the removed litter for evidence of dead birds. However the AHVLA have advised DEFRA in a letter printed in the Veterinary Record (May 2011) against the use of poultry litter on any grassland as “there is concern that the litter itself may contain the botulinum toxin, which could remain potent for many weeks”. Add to that the very real possibility that scavenging birds and mammals may pick up carcasses from fields spread with poultry litter (even after it’s been ploughed in) and carry them to adjoining fields and farms, then it’s easy to see the size of the issue and the concerns it raises.

All of the documents referred to in the above are available online with a few simple searches. It’s not highbrow investigative journalism, just simple research, something which the sensationalists media report on backyard chicken keepers seriously lacked.

So on the grand scale of things just how much of a risk do backyarders really present the poultry industry? They are a molehill in the mountain range of food production but perhaps it’s time their traditional techniques were engaged and explored and not battered when surrounded by industrial practices that contain so many question marks.

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Andy Cawthray

Author at Chickenstreet
Andy Cawthray AKA Chickenstreet is a self confessed chickeneer who writes for a number of magazines and websites, including the Guardian Blog. Andy also provides talks & courses on keeping poultry at home.

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