Whether animal feed contaminated by salmonella or E. coli 0157:H7 contributes to the overall burden of food-borne illness in humans is a contentious issue. In a letter March 26 to The Manitoba Co-operator, Graham Cooper, executive director of the Animal Nutrition Association of Canada indicated that the Canadian feed industry has adopted measures to prevent such contamination.
But how well do these measures work?
Both Finland and Sweden require animal feed to be salmonella free, but that is not the case in North America and most other countries where feed is frequently salmonella positive. For some, the link between feed contamination and foodborne illness is strong. For others, the relationship is nothing short of mythical. More extensive study of these links is needed to remove skepticism. If we ever again want peace of mind when eating spinach or lettuce salad, this issue must be resolved.
Smarter food inspection may help, but more inspection is not the solution.
The animal feed industry in Canada is large (more than $3 billion in 2000) and, as in other countries, plays a vitally important role in providing species specific diets that satisfy nutrient requirements. The industry recycles plant and animal nutrients through feed, thus contributing to agricultural sustainability. The feed industry is an international community, trading ingredients worldwide.
The U. S. obtains ingredients from South America, Asia and Africa and produces more animal feed than any other country. Production in the U. S. was over 120 million tons (primary feed) in 2004, and exports were nearly $4 billion in feed ingredients that year.
About half of the rendered animal protein used in Canadian feed is imported from the U. S. Although dried animal waste (ruminant, poultry, and swine) has been used as a protein feed ingredient in the U. S. for over 40 years, there are no national data describing how much is used in feed.
Of course, all feed ingredients imported into Canada must be registered … and poultry litter cannot legally be used as a feed ingredient here. Recycled ingredients (feather, meat, bone, fish meals) must be processed at temperatures that neutralize hazards from microbial contamination, yet more than 25 per cent of complete feed rations are salmonella positive.
The feed industry in Canada is regulated by the Health of Animals Act and the Feeds Act. The latter specifically prohibits 12 pesticides and sets limits for mycotoxins, drugs, other chemical residues and heavy metals in feed. Although it is said that the CFIA monitors feed for salmonella, there is no specific prohibition of salmonella or toxigenic E. coli from animal feed, perhaps because these zoonotic pathogens rarely make animals ill or unthrifty.
However, this represents an ignored link in the chain of recycling bacterial pathogens from animals to humans – directly by consumption of contaminated food from animals, or indirectly when these contaminants find their way to fields where produce is grown.
About 70 per cent of the animal feed sold in Canada is produced by members of the Animal Nutrition Association of Canada. Most of the industry subscribes to their FeedAssure (HACCP) program which is designed primarily to demonstrate compliance with CFIA mandatory specified risk material (SRM) handling requirements in the wake of the BSE crisis.
In a detailed examination of FeedAssure documents, checklists for reporting the absence of salmonella or toxigenic E. coli from ingredients or formulations could not be found by this writer. It’s comforting, though, that the CFIA in its 2008-09 corporate business plan reported 95 per cent or better compliance by renderers and feed mills with requirements of the enhanced SRM feed ban.
In Finland, there is an incident developing that would be unlikely to occur in North America. One of the larger feed manufacturers, Raisio Feed Company, has initiated a feed recall because of salmonella Tennessee contamination. Its feed has contaminated six piggeries, 27 egg farms and possibly five chicken meat farms. Contaminated poultry are being destroyed because of perceived human health risk and farmers are being compensated.
In North America, salmonella contamination of poultry is commonplace (up to 40 per cent), and accepted – but shouldn’t be.
It is noteworthy that in March 2008 there was an animal feed recall in Canada. Rollover Pork Tenders dog treats (High River, Alta.) contaminated with salmonella caused one human illness. Again, last month in another unusual event, a dog in Oregon became ill with salmonellosis, and dog food containing peanut butter (Peanut Corporation of America) contaminated by salmonella Tennessee was recalled.
Feed recalls for these reasons are rare and occur when humans somehow become ill. But recalls of produce contaminated by either salmonella or toxigenic E. coli are not rare, are usually large, cause serious human illness or death and are becoming more frequent.
With righteous indignation we call for more food inspection to protect us. It can’t. The prime responsibility for food safety is in the hands of producers, processors, distributors, retailers and food service workers. And while consumers also play an important role, it is impossible to wash our way to safety in the kitchen if fresh produce is contaminated with salmonella or E. coli 0157:H7.
If we were to stop feeding these organisms to animals we use as food, frequencies of animals shedding them in manure will drop, and we would take a large step forward to reduce foodborne illnesses in North America. Then on-farm food safety programs could make a useful contribution to reduce human illnesses too.
Rick Holley is a professor of food microbiology/food safety in the faculty of food science,
University of Manitoba.