African Swine Fever (ASF), Porcine Epidemic Diarrhea virus (PEDV) and Porcine Reproductive and Respiratory Syndrome (PRRS) are detrimental to animal health and performance and severely impact producer productivity and profitability. While PEDV and PRRS are endemic diseases causing reduced productivity and performance in sows and growers, ASF continues to spread worldwide, causing significant economic losses.
Feed significantly impacts the health and welfare of animals. Within the last decade, global disease outbreaks related to viruses have sparked interest in further understanding feed as a fomite for viral pathogens. Feed and feed ingredients are sourced globally and brought directly onto farms, making it more critical for feed and animal producers to understand the associated virus transmission risk of sourced materials.
Biosecurity Designed for Swine Diseases
Biosecurity programs are systems designed to keep farms free of pathogens and resulting diseases. Swine disease outbreaks, such as PEDV, PRRS and ASF, remind us that it is always essential to understand how pathogens can enter production systems, oftentimes via transmission vectors referred to as fomites.
When developing on-farm biosecurity programs, producers typically assess the risk of pathogen entry onto farms by determining how, when and where pathogen's introduction can occur. Accurately assessing risk requires the identification of possible fomites, methods by which fomites can become contaminated and enter the farm, frequency of fomite entry and potential for fomite to come into direct contact with livestock. From there, on-farm biosecurity plans, action items and personnel education programs are developed for fomites presenting the most significant risk of pathogen transmission.
Is feed a fomite for viruses?
Several peer-reviewed studies have evaluated the survival of viral pathogens in animal feed ingredients or feed products. These studies confirmed that viruses can survive in feed matrices, ascertained that some feed ingredients or feed products present a better matrix for virus survival than others, and identified selected ingredient matrices seem to enhance virus survival. In an experiment designed to simulate transoceanic shipment, ASFV demonstrated a half-life in feed ranging from 9.6 to 14.2 days. In approximately two weeks, the total viable virus concentration would only decay by half its original count. Furthermore, feed has been identified as an infectious vehicle and a credible risk to biosecurity. Studies using real-world conditions to simulate virus transmission in feed confirmed PEDV and PRRSV recovery from contaminated feed and demonstrated that contaminated feed could cause disease among the herd. Similar studies looking at ASFV transmission via feed found that the infectivity of contaminated feed is heightened due to repeated exposure, or in other words repeated herd exposure to contaminated feed reduces the viral load required for infection.
How does feed come onto farms?
present throughout the entire animal production cycle. Feed and feed ingredients are sourced and transported worldwide, coming from various climates and growing seasons. Tractors, trains, boats, trucks, flat stores, silos and feeders are all used to transport and store feed and are subject to subsequent contamination and possible secondary fomites. In turn, repeated feed exposure to these secondary fomites increases the risk of contaminating subsequent feed batches and increasing pathogen prevalence within the feed and food production chain.
How frequently is feed brought onto the farm?
Feed is delivered directly to farms and production animals daily. Feed touches everything, trucks, milling equipment, people and feeder lines, meaning it has widespread influence within multiple areas of animal production, primarily if the contamination occurs during the feed production stage.
What are the chances that feed introduces viruses to livestock?
Since feed is part of everyday animal production, the opportunity for contamination in feed to reach the herd is high. Suppose the contaminated feed is consistently fed to herds; even at a low level of contamination, the likelihood of swine disease increases. In addition, pigs are the target host for viruses such as ASF, PEDV and PRRS, so once the farm and pigs are reached, the odds of virus survival increase and the potential for host-to-host transmission occurs. Feed as a fomite significantly impacts animal production, performance and welfare because of its prominent role in swine production. Every operation has different needs and challenges. Contaminated feed has a massive impact because it touches all feeders in all houses and barns in every operation, large or small.)
Clean Feed for Swine Disease Prevention
Preventing ASF infection within a 35,000-sow operation can save an operation $60.5 million. After all, ASF infections lead to total depopulation, at least ten months of halted production and costs associated with herd disposal, facility cleaning and disinfection and herd restocking. Such a significant potential financial loss requires comprehensive swine disease prevention and on-farm biosecurity.
Managing feed as a fomite and achieving animal performance and productivity goals require that producers reduce microbial loads and the prevalence of pathogens in feed and feed ingredients. Producers milling and utilizing clean feed are better prepared to achieve operational performance and productivity goals due to lower feed-source pathogen prevalence, reduced microbial load and spoilage-causing organisms. Sourcing high-quality feed ingredients from areas free of disease for swine rations mitigates the risk associated with feed as a fomite. However, this can be challenging in times of supply shortages and shipping and transportation delays.
Chemical treatments in the form of feed additives vary in efficacy and control but grant producers the ability to implement feed pathogen control that fits each operation's specific risk. Effective feed pathogen control safeguards feed safety and helps live production strengthen biosecurity, improve animal performance, and protect the entire food chain.
Feed sanitizers, such as Termin-8® and Finio® are effective and protect against recontamination. Feed sanitation ensures that clean feed moves throughout feed production and remains pathogen-free until consumption. Both Termin-8® and Finio® have been evaluated against viruses and found to be effective at reducing the viral load in feed and preventing clinical disease.
Organic acid blends, such as Fortrol®, are applied to optimize the microbial quality of feed to improve food safety and animal performance. As a result, producers can manage their specific risks cost-effectively and flexibly by reducing feed-source pathogen transmission and preventing feed recontamination in the production process and post-heat treatment.
Clean feed supports animal production by reducing the bacterial and viral challenges entering the production system. Animals encountering lower and less variable microbial loads are better able to develop established gut microbiomes that support immune function and ensure optimal growth.