VN June 2020

Vetnews | June 2020 17 Why it’s wrong to blame livestock farms for coronavirus Alison Van Eenennaam Researcher, Department of Animal Science, University of California, Davis (originally published on The Conversation https://theconversation.com/why-its-wrong-to-blame-livestock- farms-for-coronavirus-137055) Aspartoftheglobalresponsetothecurrentpandemic,scientistsaretrying to identify the source of the SARS-CoV-2 virus. Some commentators have promoted unsubstantiated theories suggesting that “factory farming,”or intensive large-scale livestock agriculture is to blame for this virus. SARS-CoV-2 appears to have originated in bats, and possibly moved to humans via an intermediate host animal. Bats may also have been the original hosts for outbreaks that infected humans via civets in 2003 and camels in 2012. While these coronaviruses originated in animals, not one of these species is associated with “factory farming.” That makes it hard to follow the logic that farmed animals, rather than wildlife, resulted in the current pandemic. Animals, including pets, sometimes carry harmful germs that can spread to people. But studies show that the majority of emerging zoonotic diseases originate in wildlife. As an animal scientist, I have seen solid evidence that biosecurity practices associated with commercial animal agriculture decrease the risk of disease. While these practices – vaccination, physical distancing and preventing contact withwildlife - may not alignwith popular ideas of “naturalness,” they make livestock operations safer for both animals and humans. Curbing outbreaks in livestock Just as humans can experience pandemics, animal populations are also vulnerable to widespread disease events, known as panzootics. The World Organization of Animal Health estimates that illness and death due to animal diseases cause annual losses of at least 20% of livestock production globally. The world’s 1 billion livestock keepers have a strong incentive to control zoonotic diseases. These outbreaks threaten animal farmers’ health and economic well-being. In general, large-scale intensive industries are able to implement biosecuritymore effectively than small-holder or extensive industries, where animals are outdoors.Toward this end, multidisciplinary “One Health” experts work in partnership on approaches to achieve the best health outcomes for people, animals and the environment. Commercial livestock farmers consult regularly with veterinarians and animal nutritionists, vaccinate against diseases, “socially distance” their young stock from each other and physically distance their herds and flocks from wildlife to reduce their exposure to natural reservoirs of microbes. The risk of disease outbreaks increases when biosecurity protocols fail, or are absent. Cattle get pneumonia too To see how livestock farmers work to curb infectious outbreaks, let’s consider viral respiratory diseases. These pathogens can cause pneumonia in cattle, just as SARS-CoV-2 does in people. Over 1.2 million cattle die each year in the U.S. from bovine respiratory diseases – about 1% of the national herd. This disease is epizootic, meaning that it does not infect humans, and is associated with multiple viruses, including a bovine coronavirus. Respiratory pathogens spread through close contact and aerosol transmission. This is one reason why commercial dairy farmers raise their calves in hutches that are spaced roughly 4 feet apart, to prevent nose-to-nose contact. Think of it as bovine social distancing. A dairy farm in California physically distances individual calves to prevent nose-to-nose contact. (Photo: Alison Van Eenennaam, CC BY-ND) >>> 18