Pathogens are microorganisms that cause illness. Feed is a fomite for microorganisms, including bacteria such as Salmonella, Campylobacter, Clostridia and E. coli, as well as viruses such as Avian Influenza, African Swine Fever, Porcine Epidemic Diarrhea and Porcine Reproductive and Respiratory Syndrome.
Feed and feed ingredients contain nutrients and conditions in which pathogens are able to survive and, in the case of bacteria, are able to reproduce.
From feed, pathogens can infect livestock and enter the food chain, where their impact can be devastating. Millions of human lives are lost each year due to pathogen-related illnesses. In addition, disease outbreaks cost the food and farming industries billions each year through poor livestock performance and damaged business reputations.
What makes feed an ideal environment for pathogens?
Feed and feed ingredients are generally kept at temperatures suitable for virus survival and bacterial reproduction. The moisture content, even post-heat treatment or pelleting, is sufficient for bacteria and viruses to thrive. In fact, an examination of one facility by researchers uncovered that 85% of tested samples were contaminated with Salmonella.
Feed formulations are designed to meet the nutritional demands of livestock. Many of these same nutrients abundant in feed can also be utilized by bacteria. Carbon, nitrogen, salts, vitamins and minerals are good examples.
While some bacteria and viruses can survive in very alkaline and very acidic conditions, most thrive in neutral environments. Research by the USDA demonstrated that at neutral pH, most feed ingredients and feed pre-enrichments offer bacteria and viruses a close to a neutral environment. For example, the pH of broiler and layer feeds ranged from 6.2 to 7.0.
Ideal temperatures and pH, combined with the availability of oxygen, moisture and nutrients, makes feed a fomite for bacteria and viruses.
How do pathogens contaminate feed?
Feed ingredients can be naturally contaminated by bacterial and viral pathogens in the field. Wild animals such as birds, rodents and wild boars can spread bacteria and viruses through their feces but also on their fur and feet as they feed on or travel across crops.
Feed ingredients can also potentially become contaminated if they come into contact with the residues of other contaminated materials during harvesting, storage and transportation.
Once contaminated feed ingredients reach the feed mill, they undergo grinding, mixing and blending, which amplifies the spread of contaminated materials. Heat is used in many feed milling operations. Pathogens and viruses can be susceptible to heat. However, feed hygiene strategies using heat treatment to control feed-source pathogens on arrival at the mill, or during feed production, don’t solve the problem. Salmonella, for example, is widely known to live in the cooler, an area in which moisture and moderate temperatures enhance its survival and reproduction. Air is used in the cooler to reduce feed temperature and circulate contaminated dust, spreading feed-source pathogens.
Survival of bacterial and viral feed-source pathogens in feed makes it imperative that producers ensure feed is protected during transportation and storage to prevent exacerbating the pathogenic microbial load.
Our understanding of how pathogens contaminate feed continues to grow. The technology and tools we use are becoming more sensitive, enabling us to identify not only the presence of bacteria but its type, origins and populations too. In 2020, for example, Shariat et al (2020) used CRISPR-SeroSeq as a tool to reveal specific Salmonella serotypes and their prevalence in tested feed samples. Through this, and other ongoing research, we’re better able to track pathogens, develop mitigation strategies and improve feed safety.
What are the consequences of pathogens in feed?
While pathogens such as Salmonella and Campylobacter are linked to food safety concerns. Pathogens that don’t infect humans can negatively impact livestock performance, meaning higher costs and reduced outputs. For example, Clostridia and E. coli damage the immature guts of young birds, reducing the uptake of nutrients, and limiting performance for their entire productive life. Pathogens in feed can also increase veterinary costs, make livestock more susceptible to other illnesses, increase mortality and reduce uniformity.
Where pathogens in feed subsequently infect humans, the impacts can be devastating – not only for the manufacturer but for the livestock producer, food processor, retailer and consumer.
Throughout the supply chain, business reputations can be severely damaged. Farmers can lose whole flocks, herds or droves and valuable genetics, which have taken generations to develop. At the end of the food chain, consumers can lose their lives.
Salmonella, for example, causes 1.35 million cases of illness, 26,500 hospitalizations and 420 deaths each year in the United States. It’s estimated to cost the American economy $3.7 billion.
What can be done to control pathogens in feed?
Controlling feed as a fomite and feed-source pathogens requires action throughout the production process. Strict hygiene and biosecurity practices on-farm and in the mill will help prevent further contamination.
Cleaning machinery and equipment used in the production process, preventing rodents’ access, together with ensuring employees don’t introduce pathogens to the mill, are all essential elements of good hygiene procedures.
In addition, feed manufacturers can heat treat feed and apply products known to be highly effective in killing pathogens. Products that offer residual control offer protection against re-contamination during packaging, transport and storage.
Feed sanitizers effectively reduce feed microbial loads and mitigate feed-source pathogens by offering continued protection against recontamination.
Contact your clean feed expert today to learn more about feed sanitation and effective feed pathogen control programs.