NUTRITION ▶▶▶
Mitigating the risk of viruses in pig feed
While the world is holding its breath every time a new virus breaks out, veterinary researchers in the US and Canada have become particularly interested in the role feed has to play. A team of leading experts dived into the question of how viruses might be shipped around the planet.
BY TREENA HEIN, CORRESPONDENT I
t was in 2014 that the North American veterinary com- munity – as well as the worldwide feed and pork indus- tries – started to realise that viruses were being transmit- ted in feed. Porcine Epidemic Diarrhoea (PED) broke out
in the United States in 2013 and, by January 2014, the disease had arrived in Canada. “We figured out quite quickly at that point that the outbreak here in Canada was linked to a cer- tain feed ingredient, from the same feed mill, and soon there- after a research paper was published by scientists at the Na- tional Centre for Foreign Animal Disease in Winnipeg Manitoba that showed the link was possible,” explains Dr Egan Brockhoff, veterinarian at Prairie Swine Health Services in Red Deer, AB, Canada and veterinary counsellor for the Canadian Pork Council. “Then African Swine Fever (ASF) came along and since then in the US, Dr Scott Dee, Dr Megan Niederwerder and Dr Cassan- dra Jones and others have done a lot of work to look into how viruses can tag along in feed ingredients being shipped all over the world.”
How various additives inhibit viruses
Organic acids can directly inhibit virus activity, for example by suppressing gene expression. They can also prevent viruses from attaching to the surface of host cells. (In bacteria, organic acids are able to cross the membrane and cause dis- ruption by changing the concentrations of charged atoms.) Fatty acids can af- fect the virus coating, causing leakage or total disintegration of the envelope. Some essential oils (e.g. eucalyptus, tea tree and thyme) can directly inactivate free virus particles.
24 ▶PIG PROGRESS | Volume 36, No. 6, 2020
What’s been discovered Among the many other studies, Dr Dee (of Pipestone Applied Research at Pipestone Veterinary Services, MN, United States) and colleagues had published an evaluation in 2018 of the survival of livestock viruses in animal feed ingredients that were, and still are, imported daily into the US. The study involved simulated transboundary shipping condi- tions and 11 diseases of global significance: Foot-and-Mouth Disease, Classical Swine Fever, ASF, influenza A, pseudorabies (Aujeszky’s Disease), Nipah disease, Porcine Reproductive and Respiratory Syndrome (PRRS), Swine Vesicular Disease, Vesic- ular Stomatitis, Porcine Circovirus 2 and Vesicular Exanthema of Swine. For six viruses, it was possible to use surrogates with similar genetic and physical properties, but for the others actual viruses had to be used. “We found that more viruses survived in conventional soy- bean meal, lysine hydrochloride, choline chloride, vitamin D and pork sausage casings,” says Dr Dee. “These results also supported data already published on the risk of transporting PEDv in feed.” By 2019, US Department of Agriculture scientist Dr Rebecca Gordon and her colleagues had published a review of stud- ies published up to March 2018 (including the study by Dr Dee and his group) called “The Role of Non-animal Origin Feed Ingredients in Transmission of Viral Pathogens of Swine”. In their analysis, Dr Gordon and her team concluded that while some critical questions pertaining to transmission of swine viruses via feed and feed ingredients have been ad- dressed, further investigation is needed into how viruses are transmitted via feed to swine under actual field conditions. On that note, Dr Dee and his colleagues are preparing to pub- lish results of a project where virus survival was tested by placing them in feed and driving the feed around the country for 21 days to simulate in-country transport conditions. The viruses used were PRRSv, PEDv and Senecavirus A, pathogens which Dr Dee’s lab is certified to handle.
From awareness to action Because of all the research into viral survival and transmission in feed since 2015, Dr Brockhoff says the world’s pork and feed industries have become very aware of how viruses can survive in and be transported in all sorts of different feed
PHOTO: RUBEN KEESTRA
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32
