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Holding Time Calculation for Feed Ingredients

October 10, 2018 — 

Research has demonstrated the ability for certain feed ingredients to support viral survival under laboratory conditions modeled after either trans-Atlantic or trans-Pacific shipping to U.S. ports and on to locations likely to manufacture feed for swine. This has increased interest in assuring feed ingredient safety from viruses. The information below is for general informational and educational purposes only and is not to be construed as recommending or advocating any specific course of action.

The science on viral transmission through feed and feed¬stuffs is still evolving, but one study has shown the theoret¬ical ability for pathogenic swine viruses to survive transport to the United States in imported feedstuffs. Results of research provide preliminary data about the half-life time of survival ("T1/2") for those viruses studied under the conditions of the experiment. The viral T1/2 is cal¬culated based on two data points and should be considered preliminary data. Work to strengthen the data to provide more confidence in these results is underway.

Applying 13 half-lives of holding time to a feed ingre¬dient will degrade or inactivate 99.99% of a virus contaminating the feed ingredient, given certain temperature conditions. Knowing the T1/2 of the virus, it is therefore possible to calculate the theoretical holding time after the "born on date" of the feed ingredient that would be needed to inactivate 99.99% of the viral contaminate, under those conditions.

For example,

  1. T1/2 of SVA in amino acids/vitamins = 6 days 6 days x 13 half-lives = 78 days holding time between the "born on date" and use to expect 99.99% inactivation

  2. T1/2 of SVA in SBM = 22 days 22 days x 13 half-lives = 286 days holding time between the "born on date" and use to expect 99.99% inactivation

The transit time to the US of the potentially contaminat¬ed feed ingredients will vary. If the ingredient is transported in such a way that prevents further contamination, starting the hold time at seal or bagging of feedstuffs, like amino acids or vitamins, and ending it 78 days later will account for different transit times.

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