Composting and the

avian flu aftermath

By Megan Cummings

Shenandoah Valley poultry farmer Dennis Stoneburner knows what the nightmare scenario would be. In six poultry houses, each 40 feet wide by 400 feet long and each housing 25,000 chickens, the avian influenza virus (AIV) would only need to infect one bird.

Unable to isolate that one infected chicken, Stoneburner would have to kill the entire flock to prevent further spread of the virus. He would then have to dispose of all remnants of his destroyed flock and start over. Nobody, especially Stoneburner, wants dead bird carcasses.

In his 27 years as a poultry farmer, Stoneburner’s nightmare has never become a reality. But new research shows that Stoneburner could use an environmentally sound disposal method he already uses on his farm -- composting -- to respond to an AIV outbreak. Composting is just heaping up the carcasses in a way that makes it easy and quick for bacteria to break them down.

A 2004 study completed by Eric Bendfeldt of the Virginia Cooperative Extension and Robert Peer and Gary Flory of the Virginia Department of Environmental Quality showed that composting of infected bird carcasses inside the infected poultry houses (known as in-house composting) was the best way to combat the spread of AIV on Virginia poultry farms. BioCycle published their research in its May, 2006, issue.

To complete in-house composting, there must be correct amounts of carcass material, moisture, heat and oxygen. Carcass material is mixed with wood chips and chicken manure, and when bacterial activity heats the pile, the mixture loses its ammonia smell.

“It’s a hot pile of chicken manure,” Flory said. “But if you do this right, the carcasses are all contained within the poultry pile so there aren’t offensive smells beyond what you would normally smell with chicken litter.”

Bendfeldt’s, Peer’s and Flory’s research proved that, when compared with other disposal methods, in-house composting had several advantages.

“The key benefits of in-house-composting are that it keeps material on the farm, the [virus] deactivates rapidly on-site, it doesn’t require moving the material off the farm and it produces a new product that can be used,” Flory said.

However, farmers and poultry officials in Virginia believed in-house composting was an inferior method of carcass disposal because in the state’s most recent AIV outbreak in the Shenandoah Valley in 2002, in-house composting was ineffective in breaking down larger bird carcasses, Flory said.

Turkeys- some weighing more than 15 pounds- accounted for 78 percent of the 4.7 million infected birds in 2002. Poultry officials buried 65 percent of the carcasses in sanitary landfills.

Working with various agricultural and poultry industry agencies, Bendfeldt, Flory and Peer studied how in-house composting was used effectively to contain the spring 2004 AIV outbreak on poultry farms on the Delmarva Peninsula. Although the Delmarva outbreak was on a much smaller scale than the 2002 outbreak in Virginia (three infected Delmarva farms vs. 197 infected farms in Virginia), the researchers said it was a good model to use.

Flory and Peer credited Lewis Carr of the University of Maryland and Bud Malone of the University of Delaware for their help in convincing industry officials that in-house composting was the preferred method. Carr and Malone advised the study based on their experiences with in-house composting in the Delmarva outbreak.

“I went down to a poultry meeting in Roanoke and gave an update on what we learned from the spring 2004 [Delmarva] outbreak, and there was some interest in the procedure, but some turkey farmers were worried about its use on large birds,” Malone said.

“There has been a very recent and dramatic shift in acceptance of in-house composting as a [preferred] method,” Flory said. “When we started [our research] in ‘04, it was ‘no way, this could never be done in Virginia.’”

When the experiment began in November 2004, the researchers built eight windrows, or piles, inside poultry houses to test different turkey carcass treatments.

These treatments included: whole carcasses mixed and piled; shredded and tilled carcasses, mixed and piled; and crushed carcasses mixed and piled. Each windrow contained 2,500 to 3,000 pounds of turkey carcasses, with each carcass weighing between 17 and 40 pounds.

The researchers applied various carbon materials to each treatment: hardwood sawdust; aged and moist woodchips; used poultry litter; new litter or wood shavings from the brooder house; and a blend of new litter and used litter.

After two weeks, few carcasses remained in any of the windrow treatments and all carbon materials were effective in composting. The crushed carcass treatment was the first to reach 140°F (60°C), the temperature at which AIV can be inactivated in 10 minutes. The windrows with the woodchips reached and maintained the highest temperatures because they had ideal moisture levels.

By contrast, it took 16 days for the whole carcass treatment to reach 140°F. The whole carcasses also tended to roll off the compost pile and they required more carbon materials at the base and cap of the compost heap.

Flory and Peer both agreed that, when executed correctly, in-house composting was a more environmentally sound method of carcass disposal. The smell could be controlled as well, they said.

Once the process has been completed, the virus-free compost can be applied to row crops, such as corn, small grains and soybeans. If composting has been completed correctly and for enough time, no bones should remain, Peer said.

Their research explained how in-house composting limited the risk of groundwater and air pollution, minimized the risk of farm-to-farm AIV transmission and reduced transportation costs. In-house composting also reduced landfill usage, and therefore reduced landfill usages fees. In addition, in-house composting reduced the amount of time after an AIV outbreak that a poultry farm would have to be quarantined.

“Based on research and follow-up work, we determined you could move material out of a poultry house within three to four weeks,” Flory said. After the compost is removed and the poultry house is sanitized, the farmer can bring new poultry onto the farm, he said.

To properly use in-house composting, the poultry companies and state officials, not the individual farmers, would be in charge of responding to an AIV outbreak.

“There is a contractual relationship between the farmer and corporation,” Peer said. “The corporation supplies baby birds, feed, medication, and the farmer supplies the labor, utilities and the house. And in the case of a catastrophic loss, the birds are owned by the company, and the company wouldn’t want to put the farmer in a personal health risk when the bird is not owned by the farmer.”

Flory said there was a minimal chance of AIV human transmission in cases of a low pathogenic-AIV outbreak -- which would kill only a small percentage of the flock -- but that with a high-pathogenic AIV outbreak, there would be a much greater risk of human transmission. In a high-path AIV outbreak, as much as 98 percent of the flock can be infected. Although both the Delmarva and 2002 Virginia outbreaks involved the low-pathogenic virus, Flory said there was always still concern the virus could mutate to a much more infectious strain.

The future of in-house composting as an accepted response to an AIV outbreak has been assured because of the poultry industry’s acceptance of the practice, Peer and Flory said.

“I think the industry realized, in the case of avian flu, the public wouldn’t support hauling carcasses across highways to landfills around the state,” Peer said. “Also, the landfills are limited by their capacity to store carcasses.”

He did add, however, that industry and state officials needed to work with farmers and educate them about the process and benefits of in-house composting.