Every livestock producer wants to keep his or her animals healthy. Healthy animals grow better, produce higher quality products, and require fewer interventions like antibiotics. Along with keeping livestock and poultry well fed and watered, comfortable, and safe, it is important to keep them healthy by minimizing their exposure to disease-causing organisms. The incidences of highly-pathogenic avian influenza (HPAI) and porcine epidemic diarrhea virus (PEDV) in Nebraska were unfortunate reminders of the need to practice rigorous biosecurity practices to limit the spread of these and other potentially devastating diseases.
“Biosecurity” encompasses all of the practices on-farm and off that are designed to minimize the risk of disease-causing organisms from entering a farm or moving among animals once on the farm. To keep our kids and ourselves healthy, we encourage hand washing, stay home when we are ill, and attempt to avoid contact with others who are sick. Unlike with people, we can’t tell animals to cover their cough, wash their hands (or hooves!) frequently, or stay home when their sick to avoid spreading germs. Like the practices people use to remain healthy, biosecurity practices should be employed on livestock and poultry farms to keep animals healthy.
Vectors of Livestock Disease Transmission
The most important thing to remember relative to disease transmission among livestock and poultry is that if it can move, it can carry diseases! People, animals, vehicles, equipment, feed, water, pests, and air can be transmission sources for disease-causing organisms.
Livestock are often moved onto and off of a farm, from one production group to another, or among facilities or areas on the farm. Bringing animals onto a farm – whether weaned piglets moving onto a finishing farm, chicks being placed in a broiler house, or beef cattle entering a feedlot – presents an opportunity for existing animals to be exposed to disease-causing organisms carried by the new animals or for new animals to be exposed to disease-causing organisms present on the farm.
Mortalities that occur on the farm due to a disease incidence present a unique biosecurity challenge. Common diseases, such as respiratory illnesses, that often are the culprit of routine mortalities may not limit mortality disposal options. However, mortalities resulting from transboundary diseases (e.g. PEDV or HPAI) and foreign animal diseases (FADs; e.g. foot-and-mouth disease) require greater care to ensure that the disease is not spread during handling and disposal of the carcasses.
People are part of every livestock or poultry operation. Whether a worker who has close contact with animals on a daily basis or a visitor who comes to the farm on an infrequent basis, people are capable of carrying disease-causing organisms on their clothing, shoes, and bodies.
In addition to people who care for the animals on a farm, the equipment and vehicles these people operate can serve as vectors for disease movement within and onto a farm.
Feed and water are essential inputs to livestock and poultry operations. Whether the feed is processed on the farm or delivered from a mill, the opportunity for contamination should be considered. Post-production contamination can also occur, such as by rodents, birds or other pests, and feed or water contamination with manure is also a possible vector for disease being introduced to otherwise healthy animals.
Pests including rodents, insects, domestic and feralanimals that are capable of moving among areas on a farm or traveling beyond the farm boundary may pick up disease-causing organisms and ultimately expose healthy animals to those organisms.
All of these vectors warrant attention during development of a farm-level biosecurity plan. A number of resources exist for identifying effective biosecurity practices and should be utilized, as needed, when a biosecurity plan is developed or revised.
Biosecurity Practices
Limited Farm Entry
One of the most basic biosecurity practices involves limiting farm entry to only those individuals with a relevant purpose on the farm. Signage indicating the need for permission before entering the farm is recommended for all farms while an added measure, such as gated entry, may be warranted in situations where greater security is desired.
Lines of Separation
The idea of having a line or lines of separation on your farm as a biosecurity measure is something that is relatively new and again can be attributed to the PEDV issue in the swine industry. While it is a very good concept, it can be a little confusing since we usually use the term “LINE of separation” when in reality we need to think about multiple “LINES of separation”. The premise of the line of separation, though, is that at any point in a livestock system, an imaginary (or literal) line can be established to separate “clean” and “dirty” sides for the purpose of limiting disease transmission risks.
So, we may establish, for instance, a line of separation at the entrance to the farm, another at the loading chutes of our facilities, another at the feed storage area, and so on.
Pest Control
Most people consider rodents and flies to be potential biosecurity threats on a farm, but what about domestic animals? Cats and dogs are common residents of farms, so we need to consider their movement about the farm and what role they could play in disease movement. With livestock that are maintained outdoors, it is pretty difficult to control movement of domestic animals among them. But, with swine and poultry housing, it is easier to manage who and what enters those buildings, so it is best to limit entry by cats and dogs since they are not subjected to the same hygiene and disinfection steps as workers.
Vehicle and Equipment Disinfection
Trucks entering the farm to load or unload animals should have restricted access that is visibly marked or conveyed to the truck driver prior to their arrival on the farm. Personnel driving the trucks and performing loading and unloading tasks should be required to wear protective clothing and boots while on the premises and should leave these items behind when finished on the site. Truck drivers should not be allowed to enter animal housing or the loading chute area. And farm employees should not enter the truck or trailer. In this case, a line of separation is being formed at the union of the truck’s trailer and the chute.
Truck washes that are equipped to disinfect trucks are becoming more readily available and should be used whenever possible. Many of these are designed to heat and hold the truck at a temperature that kills disease-causing organisms. If these specialized truck washes are not available in your area, then truck drivers should be asked to wash trucks with hot water to remove all visible traces of dirt and manure, disinfect their trucks with an approved disinfectant, and allow the truck to dry before the next use.
Feed trucks are another potential source of disease transfer when they come from another farm or a central feed processing center. As with livestock trucks and trailers, trucks delivering feed to a farm should be treated as a biosecurity concern. If the driver is moving around the site outside of the truck cab, then disposable coveralls and boots should be provided for use while on the farm. These trucks should also be washed regularly on the outside to remove dust and manure. Disinfection of the exterior is also recommended. Again, it is important to have restricted access to the site and easy access to feed bins to minimize the movement of feed trucks on the farm site.
Employee vehicles – particularly for employees moving between farm sites – and other equipment used on the farm, such as tractors, loaders, and manure conveyance equipment, should be regarded as potential disease transfer vectors and management appropriately. Regardless of the vehicle or equipment type, effective cleaning involves washing with hot soapy water until all visible organic matter is removed, applying an approved disinfectant using manufacturer-specified practices, and allowing the equipment to dry completely.
