VN June 2020

Vetnuus | Junie 2020 18 Animal welfare groups have criticized this system, arguing that raising calves in group housing improves their social and feeding behaviour, although few studies document long-term benefits. On the other hand, commingling the animals this way poses a high risk of spreading germs. Just as humans are staying apart now to reduce transmission of the novel coronavirus, housing calves apart sacrifices some social interaction to reduce disease risks. Respiratory disease in chickens Isolating farm animals from infectious diseases spread by wildlife is a major reason why poultry and pigs are housed indoors. Animals raised in the open are at greater risk for predation and contracting infectious diseases fromwildlife. This was evident in the spring of 2018, when virulent Newcastle disease – a highly contagious viral respiratory infection – was reported in backyard chickens in Los Angeles. Since then, over 1.2 million birds have been euthanised or died from the disease. The infection has since spread to over 470 flocks in California, Utah and Arizona, most of them backyard flocks. Although vaccines are part of an effective biosecurity plan, less than 10% of backyard poultry are vaccinated. Cormorants, pigeons and doves can carry Newcastle disease, so the California Department of Food and Agriculture recommends housing poultry indoors to isolate them from wild birds. Commercial poultry farmers are now on high alert to try to protect their flocks. The biggest challenge in controlling the outbreak has been people disobeying a quarantine that prohibits moving birds out of infected counties. Global pig populations at risk China has the world’s largest pig population and provides half of global pork production. Small-scale and backyard farms with minimal biosecurity produce more than 60% of Chinese pork. Feeding pigs food waste, such as uncooked meat or food products – referred to as swill – is a high biosecurity risk, but is common practice on Chinese farms. For many years China feared the introduction of a highly contagious and deadly tick-borne virus that causes African swine fever, or ASF. This deadly haemorrhagic disease, with mortality rates approaching 100%, was first detected in Kenya in the 1920s. Since there is no vaccine available, the only approach to control the disease is biosecurity. The virus moves between pigs, wild boar and soft ticks, but is harmless to humans. Aprophetic 2017paperwarned that ASF could reachChina due to factors including international travel and commerce, swill feeding practices and the presence of wild boar populations. The disease surfaced there in 2018, likely through contaminated feed, and has rapidly spread into every Chinese province. Before the ASF panzootic, China’s pork output was almost five times larger than U.S. production. That output has dropped sharply, doubling the price of pork in China, where it is the nation’s most-consumed meat. ASF has spread to much of Asia and still threatens pig populations globally. Commercial pig producers in non-ASF countries have implemented strict biosecurity protocols, including managing feed sources, and customs agents are on high alert for smuggled pork products that could spread the disease further. Unfortunately, some travellers seem oblivious to the potentially devastating impacts of dodging biosecurity measures. Biosecurity works Livestock farmers in developed nations understand the importance of biosecurity practices. That is why scientists believe the next important emerging pathogen is least likely to originate from livestock in these countries. Inmy view, the focus should be on controlling and eradicating emerging animal diseases in resource-poor countries. Without such effort, more severe epizootic and zoonotic disease outbreaks are inevitable, threatening global health and food security. v Article Why it’s wrong to blame livestock farms for coronavirus <<< 17 Backyard chickens may seem free and happy, but are at increased risk of contracting diseases fromwild birds (Photo: Tseenster CC BY-SA 4.0) A typical backyard piggery (Photo: Kuya Frank CC BY-SA)