Building on past science This study builds on findings (from the same group of re- searchers and others) that have demonstrated that these same pig viruses can survive in feed. The capability of live- stock feed to transmit viral diseases was first proven scientifi- cally by Pipestone in 2014 during the PEDv epidemic in North America. “Since that time, various feed additives have been evaluated in lab settings for their effect on viral viability and infectivity in contaminated feed using bioassay piglet models,” Dr Dee explains. “However, studies that involve the real-world conditions of commercial swine production were needed, with larger pop- ulations of pigs, realistic volumes of contaminated feed sup- plemented with selected additives and natural feeding be- haviours.” Dr Dee and his colleagues used a new research model called an “ice block challenge” to insert equal concen- trations of SVA, PEDv and PRRSv into feed treated or not treated with additives. The ice blocks were then manually dropped into designated feed bins and the pigs were allowed to consume the feed naturally.
Towards a US feed biosecurity programme PEDv broke out in the US in 2013, and its movement into Canada in 2014 was traced back to a contaminated feed in- gredient. In subsequent years, members of the Canadian Pork Council worked with staff at the Canadian Food Inspec- tion Agency (CFIA) to create national guidelines for the im- port and handling of feed ingredients that present high risks for viral diseases such as ASF, along with storage time and heat treatment recommendations for industry. Much of this was launched in the spring of 2019. Regarding what’s been happening in this vein within the US, Dr Dee says the pork
and feed industries there have worked very hard over the last few years and have been successful in making changes to biosecurity at feed mills. “There are strong industry programmes now in place, but I and others would like to see a national government-led pig virus disease prevention and control programme pertaining to feed, similar to what is happening in Canada,” Dr Dee says. “We need a national government-driven programme with ad- ditives approved by the Food and Drug Administration (FDA) and standard operating procedures for storage time, handling and so on.” He adds, “We’ve had good leadership from industry, and we scientists are building a body of evidence on which a sound national programme can be based. A national Feed Risk Task- force has been formed, and I sit on it with staff from the US De- partment of Agriculture; FDA; Swine Health Information Coun- cil; National Pork Producers Council; CFIA; members of the poultry, swine, cattle and feed industries, and others; and we are meeting this month (September 2020). We will hopefully be able to set short-, intermediate- and long-term goals to get a programme going and discuss future research directions.”
Individual decisions Dr Dee adds that, in the meantime, now that he and his col- leagues have provided the industry with efficacy data, it’s up to individual feed companies and producers to make mitiga- tion decisions based on cost, mill specifications and so on. “We’ve discovered there are lots of additive options for virus- es of domestic interest, such as PRRSv, PEDv and SVA,” he says, “and we look forward to data from Dr Niederwerder’s lab re- garding the effect of these products in combating foreign animal diseases.”
▶PIG PROGRESS | Volume 36, No. 8, 2020 37
In the study 15 commercial additives were tested to evalu- ate their effect on mitigating SVA, PEDv and PRRSv in feed.
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