The industrial rearing of animals such as pigs, poultry and cattle to provide meat for hundreds of millions of people can reduce the risk of pandemics and the emergence of dangerous diseases such as Sars, BSE, bird flu and Covid-19 compared to less intensive agriculture , has a major Study by veterinarians and ecologists found out.
Despite reports from the United Nations and other bodies in the wake of Covid linking intensive livestock farming to the spread of zoonotic (animal-borne) diseases, the authors argue that “non-intensive” or “low-yield” farms represent a plus a serious risk to human health as they require much more land to produce the same amount of food.
This, it is argued, increases the likelihood of dangerous virus ‘spillover’ between animals and humans because it drives habitat loss, displacing disease-carrying wildlife such as bats and rodents and bringing them into closer contact with livestock and humans.
The authors of the report, published in the journal Royal Society Open Science, recognize that rapidly increasing consumer demand for meat and other animal products poses a significant risk to humanity.
“The risks of emerging infectious diseases are escalating. Livestock biomass today far exceeds that of wild mammals and birds, and livestock hosts increasingly outnumber wildlife hosts when it comes to the pathogens they share.
While eliminating animal husbandry would reduce much of the disease risk, the authors say, they argue that drastic reductions in meat consumption would be “challenging” to achieve.
Instead, the report examined whether intensive or less-intensive farming was a better option for reducing disease risk.
Worthy Farm, home of the Glastonbury Festival (with the Pyramid Stage being built in the distance). Low-yield farms require much more land to produce the same amount of food than high-yield farms, the study finds. Photo: David Levene/The Guardian
Intensive livestock farming is widely blamed for increasing the risk of avian and swine flu and other pandemics due to long-distance movement of livestock, overcrowded farms, poor animal health and welfare, low animal resistance to disease, and low genetic diversity.
But data on disease incidence on intensive farms is limited, the report says, and usually ignores how land use affects risks.
“High-yield or ‘intensive’ livestock farming has been blamed for pandemics, but those calling for a shift away from intensive farming often overlook the counterfactual — the pandemic risk of less-intensive farming, and particularly the implications for land use,” says lead author Harriet Bartlett.
“Low-yield farms need much more space to produce the same amount of food than high-yield farms. Widespread conversion to low-yield agriculture would result in the destruction and disruption of large areas of natural habitats. This increases the risk of viral spillover [ie the first transmission from a wild animal] by the disruption to wildlife potentially harboring the next pandemic virus and by increased contact between wildlife, humans and livestock.
“Lower-yielding farms tend to have larger livestock, lower biosecurity, more workers and more acreage cultivated, all of which result in different, but not necessarily lower, disease risks than higher-yielding systems that produce the same amount of food,” the report states Veterinarians and Ecologists at the Universities of Cambridge and Leeds.
A global shift away from intensive farming would require a land area nearly the size of India, which inevitably increases the risk of spillover effects, Bartlett says. “The conversion and fragmentation of natural habitats means we farm in places where livestock and people live [come into closer contact] with stressed wildlife populations.”
Evidence that zoonotic diseases are more prevalent in intensive than extensively farmed systems is hotly debated, with governments and the £150 billion poultry and livestock industry arguing that intensive farming in general is extremely safe and now essential. Animal rights activists argue that such farms are breeding grounds for disease.
According to the report, poultry farms, described as both “industrial” and “backyard,” played a role in the 2004 outbreak of highly pathogenic avian influenza (HPAI) in Thailand. However, which played a larger role – “spillover in ‘backyard’ production due to poor biosecurity allowing contact between wild and domesticated birds, or amplification and re-sorting from low to high pathogenicity in ‘industrial’ systems” – remains an open question.
It is widely believed that intensive pig farming near bat colonies led to the emergence of Nipah virus in pigs and humans and Mers in Saudi Arabian camels in 1999. Investigators from the World Health Organization have determined that Covid likely originated on a Chinese wild farm before spreading to an urban ‘wet’ market.
dr Guillaume Fournié, an epidemiologist at the Royal Veterinary College in London, said supposedly better biosecurity in intensive farms is not always a safeguard against disease spread.
The recent wave of bird flu outbreaks in Europe has “shown how difficult it can be to ensure optimal biosecurity standards and how this can lead to further spread in areas with high concentrations of farms,” he said.
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