Gary L. Bowman, D.V.M.
Extension Veterinarian, Swine
William P. Shulaw, D.V.M.
Extension Veterinarian, Cattle and Sheep
The Ohio State University
In the context of livestock production, biosecurity refers to those measures taken to keep disease agents out of populations, herds, or groups of animals where they do not already exist. Biosecurity measures are implemented on national, state, and herd levels. Currently, there is heightened awareness of national biosecurity as the United States attempts to keep foot-and-mouth disease (FMD) out of its animal population.
In addition to national concerns, individual states take measures to prevent the entry/reintroduction of livestock diseases they have been able to prevent/eliminate from their herds by setting requirements for arriving animals. Examples of diseases that are of particular concern to states include brucellosis, tuberculosis, and pseudorabies.
Herd-level biosecurity usually rests with the herd owner or management team; they try exclude any disease that is not already present in the herd or limit the spread of disease within the herd. Examples might include Streptococcus agalactiae mastitis, bovine virus diarrhea, ovine progressive pneumonia, and swine dysentery. To be successful, biosecurity plans must address how the group of animals will be isolated away from other groups, how traffic (movement of people, animals, and equipment) will be regulated, and how cleaning and disinfection procedures will be used to reduce pathogen levels.
Although infectious disease can be introduced to a farm in several ways, bringing new animals or animals that have been commingled with, or exposed to, other animals usually presents the greatest risk. New herd and flock sires, or replacement females, are often the way that new genetics are added to the herd. This seemingly innocent process is a very common way of introducing new disease-causing organisms. Producers should attempt to purchase animals from sources with known health status whenever possible. In addition, they should plan to:
Some operations, such as large poultry and swine farms, have well-developed plans for biosecurity and control of the risk that people present. In an emergency, such as the presence of FMD in the United States, even these units' plans may need to be tightened with very strict control of human access to the farm. In more normal times, consideration of relative risks allows development of practical approaches to visitors to the farm.
Visitors from urban areas, or others who have no livestock contact, present very little risk of introducing disease to the farm. Some precautions might include:
People who routinely visit farms, but who have little or no contact with animals, present only a moderate risk of introducing disease. Salesmen, feed and fuel delivery people, and mechanics are examples of this group. They should be expected to observe the same precautions as stated earlier and in addition:
High-risk visitors to the farm include inseminators, processing crews, veterinarians, livestock haulers, and livestock-owning neighbors. These people typically have close contact with animals and their bodily discharges. In addition to the earlier precautions, other recommendations might include:
Most of us don't want to offend a neighbor or a friend. Consider having a few extra pairs of coveralls and boots to loan them while they are there. If you explain to them that this is a measure to protect the health of their herd or flock as well as your own, they are not likely to take offense.
For some jobs it may be helpful to purchase rubberized overgarments that can be easily cleaned and disinfected and which don't allow fluids to soak through. Some types of coveralls, such as nylon, are less permeable than cotton and may be more easily cleaned than cotton or other fabrics. It is difficult to frequently clean many types of coats and jackets. It is possible to purchase outer layer systems that have a detachable outer nylon shell, sometimes waterproof, with inner layers for warmth and comfort. Inexpensive nylon windbreakers can also be purchased for use over top of regular coats. These outer layers can be more frequently changed and laundered, and having several can allow you to keep clean most of the time.
Fortunately, most diseases that livestock producers are concerned about are relatively species specific. Likewise, the presence of wild animals in the area does not constitute a certain risk to livestock. However, some diseases such as rabies, leptospirosis, and salmonellosis can be carried and spread by some species of wildlife and vermin such as rats and mice. Although it is impossible to completely prevent the possible contact of wildlife with our livestock, we can make barnyards and surroundings unattractive to many species. Keep grain spills or other potential sources of food cleaned up and unavailable to wildlife. Clean up old board piles or woodpiles and inspect buildings for possible hiding or denning areas. Inspect the haymow for evidence that cats, raccoons, or other animals are using the hay or the straw for denning areas or places to defecate.
Farm equipment that has come into contact with livestock or their bodily discharges can be a source of infections. Manure- hauling equipment should not be shared between farms without thorough cleaning and disinfection. Likewise, on-farm use of such things as front-end buckets and skid-steer loaders for both manure removal and feed delivery can spread diseases such as salmonella, leptospirosis, cryptosporidiosis, and Johne's disease, to name a few. Cleaning and disinfection of this equipment should be routine. Vehicle tires and under carriages can harbor disease-causing germs, especially if they have come into direct contact with animal discharges. Many germs do not survive long outside the animal, but some do, and these sources can be critical for highly transmissible diseases such as FMD.
Practical biosecurity for day-to-day situations can be achieved without the total restriction of entry to the farm that might be appropriate in an FMD emergency situation. Biosecurity requires a plan that you adhere to and a regular review of your plan to uncover deficiencies and adapt to new knowledge. It is most successful if a majority of producers adopt a workable plan. Entry of exposed or carrier animals, contaminated feedstuffs, and contaminated equipment represent the greatest threats for disease entry. With planning these risks can be limited.
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Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.
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