Reducing Pathogen Distribution from Animal Transport

(Animal Housing Environments Project)

The objectives of the Animal Housing Environments Projects are to evaluate and decrease levels of incoming and outgoing airborne contamination in swine production (including production facilities and transport of animals) through effective air filtering systems, and positively influence health and economic impacts in the animal production industry by testing means of addressing airborne contaminants including pathogens and bioaerosols.

One of the two projects in this priority area is Reducing Pathogen Distribution from Animal Transport. This project aims to develop and test a new design for animal transport trailers that seeks to facilitate control of airborne pathogen contamination, while considering operational efficiencies such as cleaning and disinfecting, and economic viability. This study will generate a practical design for an air filtration system for transport vehicles as well as information on the performance of the system for preventing infection, and information on the feasibility of the trailer air filtration design that can be immediately implemented by the industry.

This project involves a national team of researchers, analysts and knowledge translation experts from Prairie Swine Centre (PSC; Saskatoon, SK), the Canadian Centre for Health and Safety in Agriculture (CCHSA; Saskatoon SK), the College of Engineering at the University of Saskatchewan (Saskatoon, SK), the School of Population and Public Health at the University of British Columbia (Vancouver, BC) and the Canadian Agricultural Safety Association (CASA; Winnipeg, MB).

As with the other AgriSafety Program projects, knowledge translation and dissemination of findings will be conducted in conjunction with the Canadian Centre for Health and Safety in Agriculture as part of their Knowledge Translation component of the AgriSafety Program. Please visit the "Project Updates" and "Project Output" tabs for information about current activities and Knowledge Translation materials for this project.

Scientific Rationale

The growth and success of the Canadian pork industry over the past decades depended significantly on access to highly improved genetics. As part of this, many pig genetics companies have built their most valuable nucleus and multiplier farms in various provinces in the country where disease pressure is low and biosecurity perimeters are large. From these facilities, high-value breeding stock is transported for distribution to pig production areas across Canada. In Saskatchewan, most nucleus farms are located in isolated areas to take advantage of a large biosecure zone around the farm to minimize the risk of being infected with airborne pathogens. However, these high-value breeding stock inevitably would need to be transported to the commercial producers in pig dense regions of the country, thus putting these valuable genetic stock at risk of exposure to pathogens circulating in the transit areas. Transporting breeding stock is a daily occurrence across Canada, and individual farms have biosecurity procedures to ensure that the delivered animals are not introduced to the herd if infection was detected. However, the risk of infection of the breeding stock during transport can be significant, particularly during passage through pig dense areas of Quebec, Ontario and Manitoba, where disease outbreaks can still happen despite current biosecurity protocols in place. 

Microorganisms including viruses can be aerosolized, become airborne, be transmitted to other animals; be transported well beyond their area of origin, and potentially influence the health of other animals and humans. Microorganisms thereby represent major health and economic risks to producers as well as to human and animal populations. Airborne transmissible diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) can cause significant economic losses to the Canadian swine industry through actual loss in animal productivity, added costs of medication and eradication measures, and even potential loss of access to markets for Canadian pigs. Additionally, other significant swine diseases in addition to PRRS that can be transmitted airborne include Porcine Enzootic (Mycoplasmal) Pneumonia caused by Mycoplasma hyopneumoniae and Classical Swine Influenza caused by Swine Influenza Virus

(SIV). Mycoplasmal pneumonia is a highly contagious and chronic respiratory disease which causes damage to upper respiratory tract, thereby rendering the pigs susceptible to secondary infections by other pathogens, notably PRRS and SIV. Since mycoplasmal pneumonia typically occurs with other respiratory diseases, it is difficult to attribute losses due to one pathogen alone. A study in the U.S. estimated the cost of this disease at about US$4.08 per pig (in terms of lost productivity, not including cost of medications). Losses to the Canadian swine industry due to PRRS alone was estimated to be around $100 million per year. Similarly, Swine Influenza is also a highly contagious disease with close to 100% morbidity rate (i.e., rapid onset which can quickly spread to the entire herd) although mortality rates are generally low. The disease can also be exacerbated by secondary infections from other pathogens, causing reduced weight gain and resulting to increased number of days to reach market weight. Most recently, the swine industry is faced with the serious threat of another emerging disease, Porcine Epidemic Diarrhea (PED). Contaminated transport trailers were identified as one of the main routes for spreading the PED virus, but recent work have shown that PEDv can also be transmitted airborne, hence trailer filtration is an appropriate line of defence against this disease.

Thus, it is imperative that measures be developed to protect stock during transport, thereby avoiding infection of these animals and the consequent significant economic loss, and more importantly, to close this biosecurity gap through which potential infection can be introduced to high-health commercial herds.

The results from this research will lead to the protection of high-value breeding stock raised in Saskatchewan during transit as typically stock moves from areas of low disease concentration (such as Saskatchewan) to areas of higher disease concentration (e.g., Ontario, Quebec and Midwest US). In the future, it is anticipated that more barns with air filtration system will be in place in Quebec and Ontario, thus a transport trailer with air filtration system will be a necessity to complete the biosecurity coverage for transported breeding stock originating from Saskatchewan.

This study will generate a practical design for an air filtration system for transport vehicles as well as information on the performance of the system for preventing infection, and information on the feasibility of the trailer air filtration design that can be immediately implemented by the industry.

Overall, the outcomes from this work will help address one component of preventing spread of airborne transmissible diseases within the Canadian swine herds. Although beyond the scope of the present study, these outcomes can also be potentially applied to poultry and other livestock species, thereby contributing to overall sustainability and profitability of Canadian agriculture and agri-food sector.'

Aims of the Project

  1. Develop a new and improved design for animal transport trailer that will facilitate control of airborne pathogen contamination and improve operational efficiencies such as cleaning and disinfection
  2. Assemble a prototype of the developed animal transport trailer
  3. Evaluate overall performance of the newly-designed trailer for controlling airborne pathogen emissions
  4. Conduct an economic analysis of the new trailer design.

For further information about this project, please contact Program Manager Nadia Smith at 306-966-1648 or by email at nadia.smith@usask.ca.

Year 2 (2015-16) Update

The risk of infection through transfer of microorganisms and airborne transmissible diseases during transport of animals can be significant despite biosecurity measures in place. This project was formulated to develop a practical design for transport vehicles, to generate information on the performance of the system for preventing infection, and to assess the feasibility of the trailer design for immediate implementation by the industry. The survey of various industry stakeholders combined with the outcomes from the computer simulation work produced valuable information including current and additional design features needed in a new trailer design. Assembly and fabrication of the prototype has commenced, and once completed its performance in static and road tests will be evaluated.

Key Accomplishments in Year 2 include:

1. Simulation of base model (conventional trailer)

A computer model of a "base model" livestock transport trailer was generated using Design Modeler module in ANSYS. Based on the results of the computer simulation work, the following issues with the conventional transport trailer were identified:

  1. Air can come in or out of the trailer randomly in any direction, thereby pigs are highly vulnerable to exposure and contamination of airborne pathogens during transport.
  2. Temperature difference between outside and inside air can be as high as 5 °C in spite of the open configuration. In this simulation work, outside air temperature on a summer day was assumed to be 20 °C and the resulting temperature in some areas inside the trailer was 25 °C. This means that when the outside temperature reaches 25 °C which is possible especially in Saskatchewan, inside temperature could reach as high as 30 °C which causes heat stress to market pigs

2. Simulation of prototype model (initial design)

In order to address the issue of uncontrolled air movement in existing transport trailers, the prototype trailer was designed to be completely closed with only designated air inlets and outlets as openings, and fitted with an air filtration system to prevent entry of pathogen-contaminated air into the animal compartments. The computer model of the new trailer design was generated. After refining the geometry and mesh, simulations of airflow, temperature and moisture were carried out by implementing similar initial boundary conditions used for the base model. 

Through the action of fans, air entered the trailer through the inlets located at the front of the trailer, passed through the filters and exhausted through the outlets at the back of the trailer. This indicates that all outside air are pre-filtered before being distributed to the compartments, thereby confirming that this system can protect the herd from potential airborne disease contamination. 

3. Comparison of the simulation results for the two models 

Similar to the baseline case, variations in temperature and moisture inside the compartments were also apparent in the new trailer design. The first two compartments of the prototype trailer had relatively lower temperature and moisture level than those in the conventional trailer. However, temperature and moisture in compartments 3 and 4 of the prototype trailer increased; this is because air gained heat and moisture from the animals as it moved from the front towards the exhaust. Similar to the conventional trailer, all compartments were on the warm/hot side (>20 °C) during summer, with compartments 3 and 4 had air temperature as high as 26 °C. Additionally, the air velocity in the front compartments was high, which may result to thermal discomfort to animals in these compartments. To address these issues, an air distribution system was included in the subsequent simulation runs; an air distribution duct was installed in each deck of the prototype trailer to generate uniform air distribution among the trailer compartments and to resolve the issue of high air velocity in the front compartments. 

Next Steps:

Preparations for the prototype construction have been carried out while doing the final stages of the computer simulation work. A flatbed trailer has already been acquired and a trailer box for the animal compartment with features that we specified has already been ordered from the manufacturer. The fan-motor systems, filters, controllers, and other components have also been ordered. The filter bank, fans and controllers, power generator, and other components will be housed in a separate compartment to be built in front of the trailer box. Once we receive delivery of the remaining components, assembly can proceed immediately and should be completed in a timely manner.


Year 1 (2014-15) Update

The risk of infection through transfer of microorganisms and airborne transmissible diseases during transport of animals can be significant despite biosecurity measures in place. This project was formulated to develop a practical design for transport vehicles, to generate information on the performance of the system for preventing infection, and to assess the feasibility of the trailer design for immediate implementation by the industry.

The project is still in its early stages. A survey of various industry stakeholders to gain input on trailer design has been conducted. The ongoing survey has produced valuable information including current and additional design features which can be incorporated into the new design.

The project will be conducted in 4 phases. The first phase of the project involves formulation and modeling of a prototype design for the animal transport trailer through computer simulation. The geometry of the design has been generated and computer simulations are being conducted. Results of initial simulation of the trailer in a wind tunnel have been obtained. Evaluation of the design through simulation is being conducted, and includes various parameters such as temperature and air distribution, pressure drop, fan-motor system requirement, among others.  

Next Steps

In phase 2, the best design based on simulation results will be implemented in the assembly and fabrication of a prototype, followed by comprehensive evaluation using criteria such as manufacturability, costs, ease of operation and maintenance, animal welfare factors and power requirements in Phase 3. Re-design, optimization and economic analysis will be conducted in Phase 4.

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