Fugleinfluenza uhyggeligt spørgsmål:hvordan dræber man millioner af fjerkræ

Spredningen af ​​en fugleinfluenza, der er dødelig for fjerkræ, rejser det uhyggelige spørgsmål om, hvordan gårde formår hurtigt at dræbe og bortskaffe millioner af kyllinger og kalkuner.

Det er en opgave, som gårde over hele landet i stigende grad står over for, da antallet af dræbte fjerkræ i de sidste to måneder er steget til mere end 24 millioner, med udbrud rapporteret næsten hver dag. Nogle gårde har måttet dræbe mere end 5 millioner kyllinger på et enkelt sted med et mål om at ødelægge fuglene inden for 24 timer for at begrænse spredningen af ​​sygdommen og forhindre dyr i at lide.

"Jo hurtigere vi kan komme på stedet og affolke de fugle, der forbliver på stedet, jo bedre," sagde Minnesota State Veterinary Beth Thompson.

Udbruddet er det største siden 2015, hvor producenterne måtte dræbe mere end 50 millioner fugle. Indtil videre i år har der været tilfælde i 24 stater, hvor Iowa er hårdest ramt med omkring 13 millioner dræbte kyllinger og kalkuner. Andre stater med betydelige udbrud omfatter Minnesota, Wisconsin, South Dakota og Indiana.

Gårde, der står over for behovet for at dræbe så mange fugle, henvender sig til anbefalinger fra American Veterinary Medical Association. Selvom den har udviklet metoder til at dræbe fjerkræet hurtigt, anerkender foreningen, at dens teknikker "måske ikke garanterer, at de dødsfald, dyrene står over for, er smertefrie og ubehagsfrie." Dyrlæger og embedsmænd fra det amerikanske landbrugsministerium fører også typisk tilsyn med processen.

En af de foretrukne metoder er at sprøjte vandbaseret brandslukningsskum over fugle, når de strejfer rundt på jorden inde i en lade. Det skum dræber dyrene ved at afbryde deres lufttilførsel.

Når skum ikke virker, fordi fugle er i bur over jorden, eller det er for koldt, anbefaler USDA at forsegle stalde og røre kuldioxid indeni, først at gøre fuglene bevidstløse og i sidste ende dræbe dem.

Hvis en af ​​disse metoder ikke virker, fordi udstyr eller arbejdere ikke er tilgængelige, eller når størrelsen af ​​en flok er for stor, sagde foreningen, at en sidste udvej er en teknik kaldet ventilationslukning. In that scenario, farmers stop airflow into barns, which raises temperatures to levels at which the animals die. The USDA and the veterinary association recommend that farmers add additional heat or carbon dioxide to barns to speed up the process and limit suffering by the animals.

Mike Stepien, a spokesman for the USDA's Animal and Plant Health Inspection Service, said the techniques are the best options when it's necessary to quickly kill so many birds.

"State animal health officials and producers carefully weigh the different options to determine the best option for humane depopulation and do not make such decisions lightly," Stepien said.

Not everyone agrees.

Animal welfare groups argue that all these methods for quickly killing birds are inhumane, though they are particularly opposed to ventilation shutdown, which they note can take hours and is akin to leaving a dog in a hot car. Animal rights groups delivered a petition last year signed by 3,577 people involved in caring for animals, including nearly 1,600 veterinarians, that urged the veterinary association to stop recommending ventilation shutdown as an option.

"We have to do better. None of these are acceptable in any way," said Sara Shields, director of farm animal welfare science at Humane Society International.

Opponents of the standard techniques said firefighting foam uses harmful chemicals and it essentially drowns birds, causing chickens and turkeys to suffer convulsions and cardiac arrest as they die. They say carbon dioxide is painful to inhale and detectible by the birds, prompting them to try to flee the gas.

Karen Davis, of the nonprofit group United Poultry Concerns, urged the veterinary association to stop recommending all of its three main options.

"They're all ways that I would not choose to die, and I would not choose anybody else to die regardless of what species they belong to," Davis said.

Shields said there are more humane alternatives, such as using nitrogen gas but those options tend to be more expensive and could have logistical challenges.

Sam Krouse, vice president of Indiana-based MPS Egg Farms, said farmers feel miserable about using any of the options.

"We pour our lives and livelihoods into taking care of those birds, and it's just devastating when we lose any of those birds," Krouse said. "Everything that we're doing every day is focused on keeping the disease out and making sure that we're keeping our hens as safe as possible."

Officials emphasize that this virus that's spread primarily through the droppings of infected wild birds doesn't threaten food safety or represent a significant public health threat. Sick birds aren't allowed into the food supply and properly cooking poultry and eggs kills any viruses that might be present. And health officials say no human cases of bird flu have been found in the United States during this current outbreak.

Once poultry are dead, farmers must quickly dispose of the birds. They usually don't want to risk the chance of spreading the virus by transporting the carcasses to landfills, so crews typically pile the birds up into huge rows inside barns and combine them with other materials, such as ground up corn stalks and sawdust to create a compost pile.

After a couple weeks of decomposition, the carcasses are converted into a material that can be spread on cropland to help fertilize crops. In some cases, carcasses are buried in trenches on the farm or incinerated.