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The art of feed hygiene
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by Christophe Michaut, Business Development Manager, Perstorp Animal Nutrition, Sweden
ealthy and safe feed is essential for healthy and safe food – so it is important to have an efficient feed hygiene system in place to minimise the risk of pathogenic bacterial contamination of feed. For businesses, a product recall is costly as well as damaging to their reputation. For feed producers, it could also mean stopping production at a site, followed by decontamination, disposal of feed and materials. Where there is concern regarding contamination with pathogenic bacteria, measures should be taken to minimise possible hazards. Using effective methods to prevent contamination and recontamination of feed is important for both animal performance and the feed industry. In the past, formaldehyde offered a very effective solution against salmonella in feed. However, being registered as a carcinogen, it was banned in Europe in 2018. The world is now looking forward to new solutions. Organic acids-based feed hygiene solutions and heat treatment are currently considered the most efficient alternatives. Swedish additives producer Perstorp has been researching the effectiveness of other molecules and combinations of molecules against pathogens in feed for decades. They have come to know that optimal results are achieved by combining moderate heat treatment with optimised additives that prevent recontamination after the heat treatment. A finding supported by research.
Bacterial contamination of feed
REGULATION (EC) No 183/2005 mentions all the rules in the feed chain. What is commonly accepted is that both feed and raw materials must not contain salmonella within a 25g sample. Each year in the EU, 1.8-1.9 percent of samples tested are salmonella positive. Although salmonella is in focus, millers need to think about enterobacterial contamination as a whole. If only one specific bacterium is focused on, others, that are also having a negative effect on health and performance, may be missed.
Heat treatment and feed hygiene
Feed can be heat treated specifically to reduce enterobacterial
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load. Feed hygiene solutions based on organic acids, such as formic-, propionic- and lactic acid are commonly used in feed. Some of them are approved as feed hygiene enhancers in the EU. Both heat treatment and feed hygiene solutions are effective at reducing enterobacterial load. However, when feed is heat treated some beneficial species of bacteria are also eliminated. This barrier flora destruction allows more room for pathogenic bacteria to recontaminate the feed.
Combination treatments
When only using heat treatment, finished feed easily gets recontaminated during cooling and/or drying. Condensation inside machinery and air loaded with impurities will allow bacteria like E. coli to grow. Feed hygiene solutions will help feed producers to remain safe. When these products are added into the feed, trials have shown a significant reduction in enterobacteria.
Trial results: ProPhorce SA Exclusive and reasonable temperature is the best combination
In order to test the efficiency of organic acids alongside heat treatment, a SYTTAC study was carried out at Tecaliman in France. The feed was contaminated on purpose with log5 enterobacteriae to standardise the initial contamination levels. Perstorp’s ProPhorce™ SA Exclusive was added (4kg/t) to feed that was either heated at three different temperatures or not Figure 1: The effectiveness of ProPhorse SA Exclusive at reducing enterobacterial load in mash feed, with and without heat treatments (Enterobacterial load graph from the SYTTAC study 2012)