Cause for Concern?

Every time a recent foodborne illness outbreak around the world has
been analyzed, lapses in using standard sanitary practices have been
among the culprits. Yet even though practices have been tightened up,
there’s still been little progress made toward reducing overall
frequencies of foodborne illness caused by major bacterial pathogens
such as E. coli and Salmonella.

Every time a recent foodborne illness outbreak around the world has been analyzed, lapses in using standard sanitary practices have been among the culprits. Yet even though practices have been tightened up, there’s still been little progress made toward reducing overall frequencies of foodborne illness caused by major bacterial pathogens such as E. coli and Salmonella.

Controlling Contamination Animal feed ingredients that are considered to be at high risk for contamination by Salmonella include rendered animal protein meals, products from the vegetable oilseed crushing industry, fishmeal and eggshells. Advertisement

This suggests that we must look elsewhere for causes – and solutions, says Rick Holley, an industry consultant, professor of microbial ecology of food spoilage at the University of Manitoba, and member of the Canadian Food Inspection Agency academic advisory panel. Holley says many cases of foodborne illness are a result of contaminated animal waste that comes from animal feed sometimes contaminated with Salmonella and pathogenic E. coli. (Campylobacter does not appear to survive long enough in animal feed to be detected.) “There are no programs in place in Canada that adequately control this aspect of animal feed quality,” he says. “It’s a big concern.”
 
Having thrown down that gauntlet, Holley admits it’s not an open and shut case as to whether infectious agents in feed are responsible for clinical illness in humans. “We can only be definitive about that by having access to a continuous line of evidence, from surveillance of programs that monitor agents in feed and detection of infection in animals to the presence of the contaminant in animal- or plant-based foods, and human illnesses,” he says. Systems capable of monitoring sequential movement of a pathogen through this chain do not exist worldwide, and many countries only track either the first or the last two steps.

However, many studies showing a causal chain do exist, and countries in Europe have taken action. Holley says that at the U.S. Centers for Disease Control National Antimicrobial Resistance Monitoring System Conference in 2004, for example, it was estimated that 10 per cent of foodborne salmonellosis cases were caused by contaminated feed. He also notes that in 2005, the European Union (EU) recognized that animal feed was part of the human food chain in passing the Feed Hygiene Regulation. While this law does not require zero tolerance for specific zoonotic bacterial pathogens in animal feed, it does require that they be controlled by heat-treating at or above 75 C for two minutes. In all EU countries, when samples are found to Salmonella positive, feed is first treated with formic acid and then heated at pelleting.

But the fact that there’s no zero tolerance policy (that is, not all feed is screened) means that Salmonella control ranges from very strict in some EU countries to essentially none in others, says Holley. Sweden, Norway, Finland and Iceland do have a zero tolerance policy – all feed must be analyzed and be found Salmonella negative before it’s delivered to farms, and the Danish government regulatory authority (Plant Directorate) has taken the position that any Salmonella serovar is dangerous in feed.

The results of controlling microbial feed contamination in Finland and Norway for about the last 17 years has reduced the frequency of Salmonella in the animal feed supply, says Holley, “and some feel that this has reduced the rate of human gastroenteritis caused by these organisms.” However, he also notes that the Salmonella serovars that occur in fishmeal in these two countries infrequently match those that cause illness in humans, and that the majority of salmonellosis cases caused by contaminated food in these countries are acquired during foreign travel.

According to Holley, North American studies over the last 20 years have found that 25 to 50 per cent of feed ingredient and mixed (compound) feed contained Salmonella. Pelleted feed was usually less frequently contaminated (four to nine per cent).

Feed treatment: a complex issue
Reluctance to tackle the issue of feed contamination by zoonotic pathogens is understandable, says Holley, given the size and complexity of the feed industry – and the added costs that would be incurred. Feed ingredients are frequently accessed from developing countries in South America, South Asia and Africa, he notes. In addition to forages, grain, seed meals (canola or rapeseed, cotton, soybean, peanut, safflower), fats, oils, minerals and vitamins, animal feed can contain byproducts of the agri-food industry and waste streams from poultry, livestock and aquaculture operations (rendered, inedible protein, carcasses, meal). These practices can amplify and recycle zoonotic pathogens, as well as serve as a vehicle to create yet unseen future epidemic strains, says Holley.

Animal feed ingredients that are considered to be at high risk for contamination by Salmonella include rendered animal protein meals, products from the vegetable oilseed crushing industry (including meals from soybean, canola, palm kernel, sunflower, cottonseed and safflower seeds), fishmeal and eggshells. With the withdrawal of bone meal as a feed ingredient in 1991 during the BSE crisis, oilseed meals increasingly have become a popular protein and energy substitute, which has a greater influence on the final contamination of compound feeds by Salmonella, Holley notes.

What’s worse, Salmonella spp. are uniquely adapted to survive in the dry environments found in oilseed, fish meal, animal rendering plants and feed compounding mills as well as poultry rearing environments. “They can survive in niches there for years,” says Holley. “Thermal treatments used in animal protein rendering and oilseed extraction are sufficient to eliminate the organism, but final meals become contaminated after the heating step. Salmonella can survive on oily equipment surfaces and floors, be aerosolized in dust in the plant and re-contaminate the meal at cooling. Salmonella spp. are able to grow in regions of the meal where condensation on cooling equipment has contacted the meal. In compounding feed mills both E.coli O157:H7 and Salmonella have frequently been found. Strains of Salmonella more capable of forming biofilms in feed mills were most likely to contaminate the plant and feed. As with oilseed crushing mills, in compound feed mills at the pellet-forming operation, condensation at the pellet cooler and contaminated dust at the cooler air intake have been implicated as sites where Salmonella contamination of feed occurs.”

“In 2009, the U.K. government created a code of practice that sets appropriate standards for minimizing Salmonella contamination during feed mill operation,” says Holley, “but it’s voluntary.”

The Canadian picture
The Canadian Food Inspection Agency (CFIA) is responsible for the regulation of livestock feed in Canada as per the federal Feeds Act and Regulations and administers a National Feed Inspection Program “to verify that feeds manufactured and sold in Canada or imported into Canada are safe,” says CFIA manager of media relations Tim O’Connor. “All feeds must be safe for livestock, humans (by the potential transfer of residues into human food, and via worker/bystander exposure) and the environment,” he notes.

O’Connor says as part of the CFIA’s National Feed Inspection Program, feed manufacturers, including those that manufacture poultry feeds, are subject to inspection activities, including product testing, to monitor for biological contaminants. “Canada has a Salmonella monitoring program for feed that has been in place for many years,” he observes. “When a feed sample tests positive for Salmonella,  the facility from which the feed was collected must prepare a corrective action plan. This plan must address both how the contaminated feed will be handled and how the facility will prevent future contamination of feeds.” Facilities where there are recurring detections of Salmonella are placed on a more intensive, targeted sampling program to verify the effectiveness of corrective actions.”

However, although feeds are required to be free of harmful microbial contaminants, the means by which this status is achieved is not prescribed, says O’Connor. “The effectiveness of treatments for reducing microbial levels in feeds will vary depending on the feed type. The manufacturer/distributor/importer selects the most appropriate method for producing safe feed.”

The CFIA is currently working with industry to develop best practices that will help improve the safety of feeds produced in Canada. “As for irradiation of feed,” says O’Connor, “the regulatory viability of irradiation as an option to reduce microbial contamination in feed would be determined through a CFIA review of a submission from industry for approval which outlines the specific intended outcome of irradiation as a prevention for foodborne illness.”

Holley’s view, however, is that “while the CFIA has a monitoring program for feed contaminants (heavy metals, mycotoxins, organochlorine compounds-PCB), sampling for Salmonella and E. coli O157:H7 is not comprehensive.” Holley tells a story to illustrate. Following several foodborne illness outbreaks due to the presence of Salmonella in frozen chicken nuggets prior to 2007, Holley worked with Health Canada personnel and a graduate student to find the ultimate source of the pathogen. They found that it may have been animal feed, and that nine per cent of 111 pelleted poultry feed samples were contaminated with Salmonella (Journal of Food Protection, 2007 70:2251).

Melissa Dumont, technical director at the Animal Nutrition Association of Canada (ANAC), notes that her organization’s voluntary FeedAssure HACCP program, started in 1999, “goes further in maintaining feed safety than the minimum standards mandated by the federal government.” She says “The commercial feed industry is of course aware of the implications Salmonella in feed can have for poultry producers, and as a result, facilities certified under …[FeedAssure] are well equipped to deal with this risk.”

FeedAssure has “guidelines for third party carrier conveyances to ensure mitigation of the risk of Salmonella entering the feed mill,” says Dumont, and the suppliers of ingredients to FeedAssure certified mills are also evaluated for potential hazards. ANAC member facilities account for over 90% of commercial feed production in Canada. There are 167 feed mills certified under the FeedAssure program, representing about 70 per cent of the volume of feed being produced in Canada. About 140 of them produce poultry feed.

Programs like FeedAssure are a positive thing in Holley’s view, but he says the focus of the FeedAssure program is screening and record keeping relating to the absence of specified risk materials for Mad Cow disease prevention and not microbial feed contamination prevention. “I spent considerable time reviewing the FeedAssure documentation available on the website in 2008, specifically for one or more forms which would indicate that zoonotic pathogens like E. coli O157:H7 and Salmonella were tracked and whether corrective actions taken would be recorded,” he says. “I could find no evidence these organisms were part of the program. These documents are not available publically now.” ANAC has confirmed that these documents are not available to the public. Regarding Holley’s comments, Dumont says “FeedAssure is both an assurance of safety controls and a valuable business tool for the animal feed industry. Every certified mill in the program has different protocols in place to mitigate and manage risks depending on the mill specifications and the type of feed being manufactured.”

To the question of whether or not ANAC believes mandatory laws and practices to prevent all microbial poultry feed contamination in Canada are needed, Dumont says, “It is not appropriate for us to advocate a one-size-fits-all solution to potential feed contamination, as each manufacturing facility will take the steps it considers necessary, and under the FeedAssure program, risk identification and mitigation approaches are mandated to suit the circumstances.”

Holley also has concerns about on-farm feed formulation and mixing of feed. “In farm environments where Salmonella contamination is rampant and cycles of animal re-infection are continuous, the use of Salmonella-contaminated feed is quite irrelevant to the level or frequency of animal contamination,” he says, “but it does ensure a positive Salmonella status of livestock and poultry is maintained, and lengthens the period and extent of animal shedding.” He believes adoption of zero tolerance in feed at the beginning of the food continuum “will afford on-farm HACCP plans a critical control point and thereby make them useful.”

Who should pay for proposed changes in the agri-food arena, says Holley, includes both those who want to produce as well as those who want to consume safe food. (Annual foodborne illness costs in Canada, he says, are currently $11-$13 billion compared to $15-$18 billion for diabetes.) “Was it industry that paid to get the Mad Cow (BSE) prion out of ruminant animal feed? It probably paid the upfront cost, though it must be noted that this was primarily an animal health issue and not, as most seem to believe, a food safety issue,” Holley adds. “But added cost cannot be used as an excuse for inaction when it comes to food safety, and most especially where inaction would be deemed irresponsible or negligent.”

Holley concludes, “It is unlikely the recognition that the elimination of Salmonella-contaminated animal feed can serve as an effective and proactive critical control point in the food safety system will expand beyond the handful of countries where it now exists – until the spectre of litigation is raised.” He points out that “costs associated with the Maple Leaf listeriosis event were almost doubled by class action suits and individual settlements. There is an important motivating message here.”