Spreading manure: Understanding the potential disease impact

Help prevent the spreading of diseases by putting proper manure biosecurity practices in place

A truck used to help move manure on and off a farm
It is important to consider biosecurity practices when moving manure on and off the farm

With a wet spring delaying both manure application and planting, many farmers are working hard to catch up on field work. As farmers work to put manure on their fields, proper biosecurity practices should be taken into consideration.

Why is manure biosecurity important?

Biosecurity is important for the prevention of disease transmission and protection of animal health. Most swine operations have in-depth biosecurity protocols in place to safeguard the health of their herd such as, downtime prior to entering the facility and isolation periods for incoming stock. Another important consideration when building your biosecurity plan is understanding how diseases may spread through manure application. Viruses such as Porcine Epidemic Diarrhea Virus (PEDv) and African Swine Fever Virus (ASF) have been shown to be transmittable in swine manure. The awareness of how every aspect of daily farm operations can affect biosecurity is becoming ever more important.

Producers need to consider the movement of potentially infectious manure across farmland and popular farm road routes. The movement of manure has the capacity to move diseases between farms or sites within an operation, as roadways are shared by various farm operations.

What manure hauling biosecurity practices could be implemented?

The following are best management biosecurity practices for manure handling:

  • Institute proper cleaning and disinfection protocols for manure equipment; this means proper cleaning/washing to remove organic material before applying an appropriate sanitizer or disinfectant.
    • Clean, then disinfect manure equipment inside and out when moving between manure sources, different livestock sites, or fields.
    • If there is a concern of disease spread from infectious manure, have tire washing and disinfecting stations established at all possible points of entry.
  • Have dedicated routes of travel when moving manure and communicate with those using similar routes for their farm’s manure application.
    • If spreading infected manure, avoid roadways commonly used by other livestock operations.
    • Plan ahead and have an open dialogue with neighboring livestock farms regarding disease status.
      • For example, if spreading infected manure, plan to use fields away from main roadways and livestock areas.
    • Properly maintain equipment so that manure spills are prevented as you travel to and from your destination.
      • Should a spill occur, contact the Agriculture Pollution/Spills Hotline at 1-800-405-0101.
    • Utilize best management practices during land application of manure that help prevent field run off as outlined in the Michigan Right to Farm Manure Management and Utilization Generally Accepted Agricultural Management Practices (GAAMPs):
      • Incorporate manure within 48 hours of application if possible.
      • Avoid excessive application rates (apply for crop nutrient needs – soil and manure analysis).
      • Avoid frozen or snow covered ground.
      • Utilize conservation practices for prevent erosion losses to surface waters.
      • Be aware of slopes within a field (the larger the slope, the more likely the occurrence of runoff).
      • Avoid land application to saturated soils.
      • Avoid land application right before and during heavy times of precipitation.
      • Utilize tools to help determine runoff risk like the Michigan EnviroImpact Tool.
    • Have dedicated equipment, applicator clothing and footwear when completing manure transfer and application.
    • Wear different clothing and boots between sites or utilize disposable coveralls and booties where applicable.
    • Create designated footpaths and vehicle routes on the premises that diminish crossover between employees/visitors entering the facilities and those responsible for manure application and transport.
    • Understand that downtimes and health pyramids between farm sites also apply to equipment and transport vehicles.
      • Typically farms request 48-72 hours of time between visits to different sites or a completed cleaning and disinfection process of the manure transport equipment.
      • Custom applicators should visit with their contracted operations to make sure that they are following the proper site entry protocols.
    • Make sure each farm has a Standard Operating Procedure for Biosecurity and follow accordingly.
    • Keep complete records of dates of manure agitation, removal, locations visited and fields where manure was applied.
      • When working with different farm operations, a list of all sites, species housed there and dates of application/visits should be made available upon request for the producers you are working with. This is important information for tracking disease spread and biosecurity breaches.

The Future: research-based strategies to reduce virus loads in manure

Animal slurry contains antibacterial and antiviral properties (ex. ammonia) that can change the pH, especially when agitated. This, in turn, has the potential to affect different disease pathogens in the manure.

Heat Treatment:

In a study done by Turner et al. in 1999, heat-treated swine manure between 50-60° C for five minutes with pH’s ranging from 6.4 – 8.0. The more alkaline slurry required lower heat-treatment (50-55° C) and inactivated ASFV and SVDV (Swine Vesicular Disease Virus), while the more acidic slurry required a higher temperature heat-treatment (55-60° C) for the inactivation of SVDV, yet did not inactivate ASFV.

Similarly, Turner et al., 2000 demonstrated that FMDV (Foot and Mouth Disease Virus), PRV (Pseudorabies Virus), and CSFV (Classical Swine Fever Virus) were inactivated in pig slurry within three minutes when heated at high temperatures (67, 62, and 60° C).

Additionally, similar results from several pilot experiments allowed for recommendations to be made on a full-scale level, which included various heat-treatments to inactivate specific disease pathogens (60° C for ASFV, 65° C for PRV and SVDV, and 70° C for FMDV) for a minimum of five minutes. Although these are practices not commonly applied on farms, when producers are addressing disease outbreaks and the potential for spreading a foreign animal disease (FAD) these heating methods can be reviewed and adapted practices put into place to address health issues.

Additives:

Schmidt (2016), showed concentrations of PEDV in swine manure were inactivated with the addition of lime to achieve a pH of 10 for an incubation period of an hour. While this study was performed at lab-scale, it can be worked out that the amount of lime needed in 100,000 gallons of slurry is roughly 10,000 lbs. If possible to obtain lime in bulk quantities, perhaps lime could be a possible disease mitigation strategy based on this research.

Derbyshire and Brown (1979) demonstrated the possible use of calcium hydroxide as an additive to swine manure effectively increasing the pH to 11.5 and inactivating swine enterovirus and adenovirus. It is important to consider that this study is from 1979 and we now have different feed strategies and management that could affect the outcome differently today.

Potential:

While the above research trials show a viable way to potentially manage disease pathogens in manure, the feasibility of such treatments for on-farm use may be difficult. The ability to heat manure on farm with the specifications listed in the research could prove to be a daunting undertaking from an equipment and labor standpoint. The prospect of adding disease mitigating materials to slurry such as lime and calcium hydroxide may be attainable, however, the cost effectiveness would need to be considered.

Conclusions

Choose one or two biosecurity practices to improve upon immediately. Include other employees on the farm when developing and reviewing these practices. Stay-tuned for more information as we consider


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