May 24, 2005 | General


BioCycle May 2005, Vol. 46, No. 5, p. 50
When a bird flu infected poultry populations in a region of British Columbia, composting was selected as one of the carcass and manure management options.
Molly Farrell

IN February 2004, a bird flu virus began sweeping through the poultry farms of Fraser Valley, British Columbia. The Canadian government estimated that the avian influenza outbreak cost the British Columbia poultry industry at least $400 million.
When all was said and done, the avian influenza spread to 42 commercial farms and 11 backyard flocks, infecting 1.3 million birds including chickens, ducks and turkeys. The infected birds were incinerated, landfilled, or composted on-farm by the Canadian Food Inspection Agency (CFIA), which had overall responsibility for eradicating the influenza outbreak. Manure from the positive birds was composted on farm. Another 17.6 million birds that tested negative for the virus were slaughtered. The majority of the negative birds that were slaughtered were either rendered or sold to market. Approximately 1.3 million were successfully composted off-site on a large dairy farm.
The virus first infected a broiler breed flock of 9,000 birds in a barn on a British Columbia poultry farm in mid-February, 2004. The virus was a low pathogen variety, H7N3, of the avian influenza. A few days later, birds in a second barn on the farm became ill. One hundred died of a much more serious, highly pathogenic virus.
Since 1975, Canada had had three reported cases of low pathogenic H5 and H7 viruses, the latest in 2000 in Ontario. The birds’ main symptoms included sudden loss of appetite and a 20 percent decrease in egg production. According to the U.S. Centers for Disease Control (CDC), humans rarely become infected by H7, but it has happened with persons who have close contact with infected birds. Symptoms for humans can include conjunctivitis, fever, fatigue, cough, sore throat, eye infections and muscle aches. (See sidebar describing the avian influenza virus.)
On March 1, 2004, seven Asian and South American countries suspended the import of live poultry and poultry products from Canada. Another seven countries limited the ban to poultry products from British Columbia. (Approximately seven percent of Canada’s poultry production is exported.)
In mid-March, the CFIA confirmed a second case of H7N3 influenza in a second Fraser Valley farm that had four flocks of diversified poultry. Testing showed the strain to be H7N3, the same as at the first farm. To stem the outbreak, government officials established a 5-km high risk “Hot Zone” area around the farm. Outside that was a 10-km Surveillance Zone. The entire Fraser Valley became the Control Area, where strict movement controls were instituted. The officials suspected that the virus was spreading from one farm to another by people carrying the virus on their boots and clothing, or on farm vehicles and equipment.
By March 23, 2004, avian influenza had been confirmed on five farms, all within the high-risk region, affecting approximately 90,000 birds. As a precautionary measure, the CFIA ordered approximately 275,000 birds destroyed at 10 poultry farms and 33 smaller flocks in the hot zone. The barns were sealed and carbon monoxide gas was pumped in to destroy the birds. The carcasses were then transported out of the hot zone in sealed, disinfected trucks to be incinerated.
In early April, flocks in farms both inside and outside of the hot zone tested positive for avian influenza. As the number of infected birds grew, options for their disposal narrowed. The mayor of Princeton, British Columbia, where hundreds of thousands of birds were being incinerated, refused to take additional birds for incineration. Rendering companies only agreed to take birds testing negative.
On April 5, the CFIA ordered the preemptive slaughter of 19 million birds in the Fraser Valley, including all commercial and backyard flocks. In total, 18 farms had been affected to date, including 12 flocks in the high-risk area, four in the surveillance zone and two in the control area.
Of the approximately 17.6 million birds destroyed, most tested negative for the virus and were sold to markets. Some also went to West Coast Reduction in Vancouver for rendering. The Canadian government initially tried to incinerate or landfill the remaining carcasses, but incineration proved expensive and residents living near the participating landfills organized blockades in protest. As an alternative, farmers and farm suppliers approached the government about composting the carcasses and manure. (Editor’s Note: The composting trials in the Fraser Valley also involved on-farm management of positive birds. Those results will be discussed in a future BioCycle article.)
Just under 1.3 million of the negative birds were composted on Vyefield Farms, a large dairy farm in Abbotsford, British Columbia. The CFIA and Provisional Emergency Program – formed by the Ministry of Agriculture to oversee the cleanup – both preferred a central site for the negative birds and manure, instead of composting at the farms where the birds were being raised. The Ministry of Agriculture was responsible for providing options for safely disposing of the infected poultry carcasses and manure. “Security was a top priority as well as quality control, and both could be more efficiently managed at a central site,” says Ed Kielstra of Vyefield Farms. Kielstra had been composting dairy cow manure in windrows for years, and had been using a Versa 1012 Silage Bagging machine for storing feed in silage bags. Kielstra was asked by CFIA if he would be interested in using the bagging machine to fill bags with feedstocks for composting.
He also was approached by Bryan Arthur of Pacific Forage Bag Supply Ltd. to use the Vyefield Farm property for composting birds using the Ag Bag method. Arthur and his wife Diane own Pacific Forage Bag Supply Ltd., which is the British Columbia dealer for Ag Bag International and Ag Bag Environmental storage and composting systems. Pacific Forage had mainly sold the Ag-Bags for cattle feed storage, but Arthur began in-vessel composting of manure and chickens, green waste and biosolids with the Ag Bag system in 1998. When the avian flu outbreak occurred, Arthur contacted the CFIA and other agencies about using the Ag-Bag Environmental systems to compost chickens.
Arthur says the idea of using the in-vessel bagging system was not embraced by the members of the Ministry of Agriculture and CFIA in his first talks with them. “Initially they considered putting all the birds testing negative in a bag and holding them there until they figured out what to do,” he says. “I said, well why don’t we just compost them?”
In the meantime, Kielstra had contacted Versa Corporation to see if his silage bagging machine could be modified for use in composting. While Versa worked out the details for a bagging machine, the company put Kielstra in contact with Harvey Funk of Compost Technologies Inc. (CTI) to help develop the project. (Versa Corporation and CTI have recently entered into an agreement to develop a division within Versa to implement composting projects under the name of Versa Compost Technologies.)
Within a few days, Kielstra submitted a proposal to the Provincial Emergency Program to use 20 acres of the 150-acre farm for the composting project. The Fraser Valley Regional District Solid Waste Management Plan had to be amended to allow the birds to be composted at the location. The Provincial Emergency Program accepted the proposal and hired Dr. John Paul of Transform Compost Systems (TCS) of Abbotsford, BC as a consultant to monitor the project. To compost the negative birds, the Ministry of Agriculture selected the Ag Bag Environmental system provided by Pacific Forage Bag Supply Ltd., and CTI’s enclosed aerated static pile bag system.
The Vyefield Farm project was paid for by the Provisional Emergency Program. Pacific Forage was offered $23.85/cubic yard (cy) to compost the birds, reports Alexis Arthur, who helped coordinate Pacific Forage’s composting effort with her father. “I know that it was a heck of a lot cheaper than incineration,” she adds. Pacific Forage provided a HyPac 7000 dual silage/compost machine.
Because of time constraints, Vyefield Farms purchased a Versa 912 Compost Model bagging machine instead of modifying the existing Versa 1012 to fill the CTI System bags. The local power company responded quickly and installed power for the aeration blowers that would be used on the 20-acre composting site. “The CTI bags as well as aeration pipe and blowers were delivered to the farm within five days of being ordered,” says Funk.
The birds were gassed with CO2 on the poultry farms and the carcasses and manure were delivered to Vyefield Farm in large, enclosed container trucks, beginning on April 23. The birds and manure were dumped into a covered bunker where Vyefield Farm stores sawdust and machinery. “The farm had a large woodpile outside the bunker,” notes Alexis Arthur, who was at the farm every day to monitor the project. “It was a mixture of large chunky wood and shavings that was nice to put through a grinder and provided a good amount of porosity in the compost mix to allow airflow through the bags.”
The dead birds and manure were blended with ground wood residuals. “The ratio fluctuated due to the sizes and amount of birds,” notes Arthur, “but the average was one front end loader bucket of birds, one-half bucket of manure, and three to four buckets of ground wood.” Mixing and blending started with a loader before the feedstock was shredded in a Beast Bandit horizontal grinder. Separated dairy manure liquids were added during the grinding process to provide approximately 55 percent moisture by weight.
Two trucks were used to transport the feedstock from the grinder to the bagging machines. The shredder had a conveyor that dumped the shredded materials into the back of the truck. “When we started,” notes Alexis Arthur, “a huge number of birds had already been dropped off, so there was a bit of a backlog of birds at the beginning. It took about two days to get everything into the bags.” In the two-week period starting April 23, about 1.3 million birds and associated litter were delivered. All of the birds and manure were bagged by May 19, says Arthur. In total, 22,400 cubic yards of feedstock were placed in 16 CTI System white bags and 16,500 cubic yards were placed in 30 green Ag-Bags. Each Ag-Bag measured 10 feet in diameter by 200 feet long, and each CTI System bag measured 12 feet in diameter by 350 feet long.
Two lengths of four-inch diameter and 150 foot long perforated flexible corrugated tubing were inserted into each Ag-Bag. The Ag-Bags were aerated 33 percent of the time, four minutes on and eight minutes off. The reusable smooth-walled CTI System pipes were perforated by drilling holes to meet the design criteria of hole size and spacing. The CTI bags were aerated 50 percent of the time, four minutes on and four minutes off. Odors were monitored twice daily, at 8:00 a.m. and 8 p.m., at seven locations on roads near the compost site. “Odor was distinct at times, but only directly downward of the composting site,” notes Paul. “No odor complaints were received by government agencies.”
Temperatures in the bags were recorded twice a day during the first week and then weekly for another six weeks. Thirty data points were measured on each bag at each sampling time, at depths of 6-inches, 3-feet and 6-feet, using a 6-foot probe. Surface temperatures were compared between the two brands of bags. “One thing we learned is that the CFIA could also have composted the avian flu-infected birds with the bag system, because every bag reached a temperature of 130°F within days,” says Arthur. “The temperatures just skyrocketed.” Temperatures remained high during the composting process, well above the required 55°C for pathogen kill.
Fecal coliforms were measured in select windrow bags after one week, two weeks and six weeks of composting. Seventy-five percent of the materials had less than 1000 MPN (Most Probable Number per 100 g sample) after one week. Ninety-five percent of the bags had less than 1000 MPN after two weeks and 40 percent of the bags had less than 1000 MPN after six weeks. “The percentage of white and green bags with less than 1000 MPN decreased over time because some regrowth occurred, requiring further windrowing and turning,” explains Paul.
The bags were opened after eight to 12 weeks. Only a few small bones and feathers remained of the chickens. However, the Solvita compost maturity index test indicated that the compost had a maturity level of four, requiring further composting and curing for contents of both the green and white bags. Windrows were formed and turned several times during the six-week curing process. “The turning resulted in consistent moisture content and further drying,” says Paul. The Solvita index increased from four to six for CO2 after seven additional weeks of windrow composting. The contents of the white bag were drier and contained less ammonia than the green bags, due to greater aeration rates.
From the initial 39,000 cy of feedstock, about 23,000 cy of compost were produced. The final product was screened with a Fecon screen. All of the compost was kept by Vyefield Farm. Some is being sold and some will be used on-site in farming operations. The final compost analysis, according to Paul, was N-P-K ratio of 1-2-1, pH of 7.8, C:N ratio of 18.6, and electrical conductivity of 3.7 dS/m.
Asked if he would do it again, Kielstra responds “Definitely yes. We were able to help solve a critical problem in an environmentally favorable manner, resulting in a valuable end product.” Adds Alexis Arthur: “It was a great experience. We had people visit the compost site from New Zealand, Japan, and across Canada. Also, many CFIA representatives are veterinarians. They are taught that when it comes to mortalities, to bury or burn them. A number of them are now saying that this project is changing the notion of dealing with dead stock.”
Transform Compost Systems (TCS) was hired by the Sustainable Poultry Farming Group to deal with manure that tested positive on the farms. The Sustainable Poultry Farming Group is an Abbotsford-based organization funded by various poultry growing associations to address manure and environmental issues.
John Paul of TCS says the poultry manure on farms that tested negative was managed as usual, i.e., spread on farms or shipped off-farm for mushroom compost production or crop production elsewhere. The positive birds had been incinerated but the barns still had manure. According to Paul, TCS and the Sustainable Poultry Farming Group followed four principles outlined by the CFIA when developing the protocol for deactivating the virus in manure from farms that tested positive for avian flu: 1) Minimize aerosol formation because the avian flu virus is thought to be potentially transmitted by dust particles; 2) Minimize risks to human health; 3) Ensure adequate pathogen kill; and 4) Be practical and design a process that could be done on the farm at reasonable expense.
Six broiler-breeder and five layer farms were involved in the project. Separate protocols were developed for broiler-breeder manure and layer chicken manure. The broiler-breeder manure was first mixed in the barn. “The manure was dry on one side, and wet underneath the waterers,” explains Paul. “Mixing moistened the dry material to minimize dust.” The manure was transferred by a conveyor to a Supreme EnviroProcessor vertical auger mixer that blended the wet and dry manure. If the mixture was too wet, it was mixed in a 1:1 ratio with sawdust in the vertical auger mixer. No other carbon or bulking agent was added. The result was no aerosols and a blend of wet and dry manure that self-heated within 12 hours. The blend was brought outside of the barn and windrowed.
The windrows were sprayed with insecticide and lime was applied to the edges of the windrows to control dark-winged beetles. “The beetles could have left the composting pile as it heated and flew off to another poultry operation, a possible mechanism of transmission of the avian flu virus,” says Paul. The windrows were covered with a Tyvek vapor barrier; a four-inch layer of sawdust was layered on top of the Tyvek for insulation.
A different protocol was needed for composting the layer manure as it was very wet. “It had 70 to 80 percent moisture and was very dense,” notes Paul. “There were no concerns with aerosols or dust because the manure was too wet. The big concern was with heat development because of the high moisture content and the density of the material.” To correct this, the poultry producers purchased sawdust and shavings and blended the layer manure up to 1:1 by volume with the sawdust or shavings. Windrow formation and management were the same as for broiler breeders.
On a separate farm with layer manure, forced aeration was added. “It was the last farm and there was a sense of urgency in treating this manure so that the area could be considered virus free,” explains Paul. “The poultry industry wanted rapid signoff on the manure so the producers could repopulate and get on with production.” The volume ratio of manure to sawdust was 1:1. Three-inch pipes were laid on the ground over plastic, and covered with a 14-foot wide by six-foot high windrow. A temperature of 70°C was achieved within 24 hours, and there was a signoff in three days.
In all cases, manure was composted for at least four to six weeks, says Kevin Chipperfield of the Sustainable Poultry Farming Group. However, for the CFIA to release the manure piles from quarantine they were required to reach 50° to 60°C for a period of time – the higher the temperature, the less time required. “A total of 1,620 cy of manure were composted on the broiler-breeder farms; 2,460 cy of manure were composted on the layer farms,” says Chipperfield. “Several farmers spread the compost on their farms but most was marketed off-farm. I have marketed a good portion as a topsoil additive/nutrient source.”
Sidebar p. 52
MIGRATORY waterfowl, most often wild ducks, are the natural carriers of avian influenza viruses; they are also the most resistant. The wild birds that host the virus are not likely to become sick from it, but can spread the influenza to other birds. Domestic poultry, including chickens and turkeys, are most susceptible.
The most common mode of transmission of the virus is through contact with contaminated nasal, respiratory or fecal matter from infected birds. The most common form of transmission between birds is the fecal to oral transmission. While domesticated birds can become infected through direct contact with infected waterfowl or poultry, they also can be infected through contact with surfaces (dirt, cages) or materials, such as water or feed, that have been contaminated with the virus. In addition, people, vehicles and other objects such as cages can spread the virus from one farm to another. The result is an avian influenza outbreak among poultry. When these outbreaks occur, quarantine and depopulation and surveillance of the affected flocks are the preferred control and eradication methods.
There are several different forms of bird flu. They range from the low pathogenic form which often goes unnoticed except for lower egg production to the high pathogenic form which is more severe and spreads rapidly, killing many of the infected birds. Three subtypes of the avian influenza virus, H5N1, H9N2 and H7N7, have crossed the species barrier between birds and humans. For example, a recent outbreak of H5N1 avian influenza in Vietnam has resulted in the infection of 41 individuals within 18 cities and provinces since mid-December 2004. Of these cases, 16 have died while six remain under treatment.
Transmission of the bird flu to humans is most often through contact with the droppings of infected birds as well as poor sanitation and slaughtering practices in poultry markets. To date, there is no documentation of sustained person-to-person transmission of the H5N1 virus (i.e., it remains fairly local). The concern is that the avian flu virus could mutate or combine with a human flu virus and spread rapidly from human to human.
The World Health Organization notes that several measures can help minimize the global public health risks that could arise from large outbreaks of highly patho-genic H5N1 avian influenza in birds. Halting further spread of epidemics in poultry populations is an immediate priority, reducing the opportunity for human exposure to the virus. Additionally, vaccinating individuals at high risk of exposure to infected poultry using existing vaccines effective against currently circulating human influenza strains, can reduce the likelihood of co-infection of humans with avian and influenza strains. Workers involved in the quarantine and depopulation of poultry flocks must be protected, by proper clothing and equipment, against infection and should also receive antiviral drugs as a prophylactic measure. – Karen Kelly

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