Eradication of a foreign animal disease outbreak, like highly pathogenic avian influenza, requires the depopulation and disposal of all the poultry on infected premises. Quickly euthanizing and disposing of the flock reduces the opportunity for tracking the virus off the infected premise on either people or equipment.
Gary Flory, Agricultural & Stormwater Program Manager, Virginia Department of Environmental Quality, said water-based foam can be used to rapidly euthanize floor-reared poultry flocks. He told the audience at USPOULTRY’s Live Production & Welfare Seminar that poultry euthanasia with foam followed by in-house composting of the carcasses in windrows of poultry litter work very well and help to keep the virus contained in the poultry house until it is inactivated by heat in the compost pile.
This outdoor windrow formed on a layer farm has a carbon base made of ground waste trees, with the mortalities placed in the middle. A carbon cap will be placed on top.
Unfortunately, euthanasia and disposal of cage housed laying hens presents a much tougher challenge. Foam doesn’t work well in cages and there isn’t any place to compost birds in a manure belt house.
Flory, who has helped poultry producers in Virginia and West Virginia with mass depopulation and bird disposal issues in prior low-path avian influenza outbreaks, helped out with poultry carcass disposal in the highly pathogenic avian flu outbreak in Upper Midwest this year. He said the mass euthanasia and flock disposal experiences on layer farms last spring demonstrates the need for all poultry farms to have site-specific plans approved and in place before a disease outbreak starts.
Workers smooth out the cap of this windrow to make sure all of the carcasses are covered.
Poultry euthanasia options
By the time a low-path avian influenza outbreak occurred on a turkey farm in Shenandoah County, Virginia, in 2007, Flory said that using water-based foam to euthanize poultry followed up with in-house composting with the poultry house litter were proven methods for euthanizing and disposal of floor housed poultry. The standard method for euthanizing cage layers requires removal of the birds from the cage and placement in a container or “kill cart” where the hens are euthanized with carbon dioxide gas in groups of 150 to 200 birds.
Flory said that, on a cage layer farm in Nebraska where he assisted with disposal of the mortalities, a crew of 170 people was used to euthanize the hens. Even with a crew of this size, he said that they could only euthanize 120,000 birds per day. With many U.S. cage layer farms now housing a few million hens each, “It takes a long time to make this work,” he said.
Remember that, as long as the birds are alive, they are shedding virus. Each additional day that it takes to euthanize the flock is another day the birds are shedding virus into the environment and provides more opportunity for the virus to get tracked off the farm by people and equipment.
Because it can take weeks for a large crew of people to euthanize a farm with a few million cage-house hens, Flory suggested that other means of depopulating these houses need to be developed and employed.
“Ventilation shutdown: we need to continue this conversation,” he said. “We have heard from the highest level at the USDA that, ‘We aren’t going to stop it,’ if a company chooses to do that. Is that approval? I don’t think that is approval.”
“We are having lots of conversations about that with USDA and AVMA, whether or not ventilation shutdown might not be a more quick, effective and even humane way of euthanizing these flocks.”
Flory said there are concerns that delays in getting flocks euthanized may have increased the size of the outbreak.
Carcass disposal options
During prior avian influenza outbreaks in the U.S., on-site burial, landfill burial, incineration and in-house composting have all been used as disposal measures for euthanized poultry flocks. Flory said in-house composting has become the disposal method of choice because the heat of decomposition in the pile effectively destroy the virus and the compost is safe to use as a soil amendment.
Of the 109 affected farms in the avian influenza outbreak in Minnesota, 108 used in-house composting and only one used on-site burial. The 21 depopulated farms in Wisconsin, Nebraska, California, Missouri and North Dakota all used composting as the means of disposal. The 11 farms in South Dakota and Arkansas all used burial. The 71 farms depopulated in Iowa used a combination of burial, incineration, composting and landfilling as means of carcass disposal.
Develop a euthanasia and disposal plan
“You have to plan depopulation and disposal as a unit,” Flory said. He cited an example from an Iowa layer farm as an example of what can go wrong when you don’t have prior approvals in place before an outbreak. On one layer farm, it took 41 days to get approval to move the euthanized birds to the landfill for disposal. Carcasses that sit in a bag for 41 days waiting to be buried are no longer “solid waste” and this presents additional challenges for handling and transport.
Every farm needs a site-specific plan for mass depopulation and disposal, according to Flory. If you plan on landfilling the mortalities, make sure you have agreements in place now.
He suggested that layer farms really need to consider how they can compost birds on-site. Producers need to figure out how much space it will take to compost all of their birds. Flory asked, “What will your carbon source for composting be? If you have to do the composting outside of the house, where are you going to do it?”
Flory said a farm-specific plan also needs to address what you will do with feed and/or grain that is stored on-site.
“What if you have 210,000 bushels of corn on the farm?" he asked. "Can it go to an ethanol plant? Can we leave it on the farm in the bin, then test it later to see if there is any virus in it?”