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Frequently Asked Questions on Bovine Spongiform Encephalopathy (BSE) and its Impact

Mr. Jim Akers, Dr. Darrh Bullock, Dr. John Johns, Dr. Lee Meyer, Dr. Benjy Mikel and Dr. Patty Scharko
University of Kentucky

Printable PDF version

Information relevant to producers and consumers. Impact on beef marketing and management



I. Information relevant to producers and consumers.

What is Bovine Spongiform Encephalopathy (BSE)?

Bovine spongiform encephalopathy (BSE), commonly referred to as "mad cow disease," belongs to the family of diseases known as transmissible spongiform encephalopathies (TSE). The causative agent of BSE has not been fully characterized, but three possibilities have been proposed: an unconventional virus, a prion (a self-replicating protein), or a virino (incomplete virus) comprising naked nucleic acid protected by host proteins. The theory accepted by most scientists is that BSE is caused by a prion. The agent does not invoke a detectable immune response or inflammatory reaction in its host and is extremely resistant to sterilization processes. The brain of affected animals appears “sponge-like” when observed microscopically in these various forms of TSE.

What is a Prion?

A prion is an altered protein. It is not DNA or a virus, which were previously the only known mechanisms for a protein to have the ability to replicate, or reproduce. Prions do not replicate, however, they attach to other proteins and cause them to change into the same form as the prion. In normal situations this is not a problem and naturally occurs in the body. With normal prions the cell breaks down the prions and reuses their parts. The cell does not have the ability to break down the abnormal prions associated with TSE diseases and therefore a buildup occurs.

Do TSEs occur naturally?

Yes, disorders of this nature have been known for centuries. The following is a list of known related disorders:

Scrapie in sheep (diagnosed in 1732 with a breed susceptibility in Suffolks)
Chronic Wasting Disease in Elk/deer
Feline Spongiform Encephalopathy
Transmissible Mink Encephalopathy (diagnosed in 1940’s)
Creutzfeldt-Jakob in humans (CJD, diagnosed in 1920, appears to have a genetic and/or sporadic component (1 case per 1,000,000 population per year))
Kuru in humans in New Guinea (diagnosed in 1900, ancestral cannibalism)

How do cattle get BSE?

The only known way for cattle to contract BSE is through consuming feeds that contain specific byproducts from affected ruminants (brain, spinal cord, eyes and distal small intestine.)

What are “downer cows”?

“Downer cows” are cattle that cannot walk or rise from a lying position, due to any number of reasons.

Are all "downer cows" infected with BSE?

No, over the past year approximately 15,000 downer cows were tested for BSE in 2002-2003 and the one case in Washington was the only positive report. Additionally, 57,352 (as of September 30, 2003) cattle have been tested from slaughter plants by USDA. Our diagnostic labs in Kentucky have routinely tested cattle exhibiting neurological symptoms for many years and no cases of BSE have been found.

I had a cow that had symptoms like BSE. Did she likely have BSE or are there other disorders with similar symptoms?

It is highly unlikely that your animal had BSE. There are a multitude of neurological disorders or other diseases that cause weakness, trembling or other symptoms that mimic BSE. Cattle with something as simple and common as pinkeye can demonstrate similar symptoms. Common diseases affecting the brain of cattle may include: listeria (circling disease), polioencephalomalacia (thiamine/B1 vitamin deficiency), rabies, grass tetany, milk fever, and ketosis.

Can you test live animals for BSE?

No, currently the only reliable test is on brain tissue which requires the animal’s death for collection.

Can BSE be passed to offspring from infected parents?

It is not likely that cattle can transmit BSE to offspring; however, the research is not conclusive. Research in Great Britain indicated an increase of approximately 9% occurrence of BSE in calves from infected dams. There is no evidence that this resulted from direct transmission rather than from inherited susceptibility/resistance. Research in other species indicates that susceptibility/resistance is inheritable. For example, some lines of sheep are resistant to Scrapie which is a transmissible spongiform encephalopathy in sheep.

What can I do to insure that my cattle don’t get it?

The practice of feeding animal by-products that may contain prions has been banned in the US and Canada since 1997. Compliance with this law is mandatory.

What age cattle normally have BSE?

Cattle don’t “normally” have BSE but when it is diagnosed it is typically seen in cattle between 3 and 6 years of age; primarily dairy cattle. One case of BSE has been confirmed in a 24 month old animal in Japan.

Why do the cattle associated with the confirmed cow have to be destroyed?

There is no scientific reason to destroy them if they do not demonstrate symptoms of BSE since they cannot transmit it to other animals. However, because the only method of testing is to harvest brain tissue you will probably see some, if not all, of these animals sacrificed for testing. The additional herds now under quarantine are not a result of more cases but rather the expanding search for the cattle that entered the US with the confirmed animal.

Can humans develop BSE?

There has been an observed association with a new variant Creutzfeldt-Jakob disease (vCJD) in the United Kingdom since BSE was first diagnosed. Case diagnoses appeared after BSE diagnosis, then case numbers increased for several years, peaking in 2000, but the case numbers are now decreasing annually. vCJD affects younger people (28 years old versus > 60years for CJD) and has a longer clinical duration (14 months versus 5 months for CJD).
Between 1996 and 2002 most vCJD cases (129) have been diagnosed in the United Kingdom, six cases in France, and one case each has been diagnosed in Canada, Ireland, Italy, and USA (WHO website). The one known case in the US is a young woman that spent the first 13 years of her life in England.

United Kingdom CJD stats

If a person were to eat beef from cattle with BSE what are the health risks?

There has been no direct association between meat from BSE cattle and human health risk. The only known transmittance of BSE from cattle to humans is when humans consume tissue from the central nervous system (brain and spinal cord) of an infected animal.

Are there any common human food products that have cattle central nervous system tissue in them?

No, not if products are produced under current guidelines and regulations. The upgraded USDA processing guidelines should virtually eliminate the possibility of these parts of the carcass finding their way into processed foods by accident. Consumers should be aware that almost any part of a carcass, even brains and ox tails, considered a byproduct by many, might well be considered a delicacy by some segment of the population and therefore be available for purchase in some meat cases. This situation is becoming more prevalent as the US becomes more diverse in major ethnic population markets.

What happens to the infected products when rendered?

The Washington State case was rendered into candle wax and soap. Rendering could mean the product could possibly go for uses such as pet foods, poultry or swine feed supplements and fertilizers to name a few.

Is there danger to my pet from eating rendered nervous tissue?

Rendered products have been major components of companion animal feeds for many years and no associated problems have ever been found with canine pets. However, there is a similar disorder found in felines and it appears that it can be caused by consumption of feed contaminated with the BSE agent.

Explain the newly announced USDA rules changes.

On December 30,2003 Secretary of Agriculture Ann Veneman announced changes in procedure in the meat processing industry. First and foremost, non-ambulatory disabled “downer” animals are now banned from human food or contact with human food processing. AMR, or advanced meat recovery technology, is no longer acceptable as a means of processing cattle over the age of 30 months for human food. Air injection stunning is now banned. Cattle can no longer be tagged “inspected and passed” if they are suspected of having BSE. They must be held until they are tested negative for BSE.

Is our beef safe?

Yes, we have one of the safest and comparatively cheapest food supplies in the world. Every animal that is harvested for commercial sale is inspected both pre and post harvest by a trained USDA inspector. This is why we know about the one case in Washington State – a federal inspector identified the need to test this one animal.

II. Impact on beef marketing and management

How will the new USDA rules affect prices?

Downer cows have not been accepted by stockyards in recent history. Beef producers are not expected to experience a reduction in prices due to the changes. If there is any reduction in prices it would logically be in the slaughter cow sector of the market as the uses for the resulting product would have some limitations and there would be a somewhat lower yield of product due to the processing limitations. Downer animals will now be a loss to whoever owns them as has been the case for most beef producers for some time now, these animals will be rendered.

What are the short run market impacts?

Prices for slaughter cattle and wholesale beef have declined – largely due to uncertainty and expectations of increased domestic supplies. Prices declined from record-high levels, so now slaughter cattle are selling near the prices of a year ago and $10 per cwt. over the price level of mid 2002.

The U.S. exports about 9% of its beef production. Because countries have temporarily closed their doors to U.S. beef, the supply of beef on the domestic market will be increased as the beef intended for export is diverted to the U.S. market. Economic research suggests this will have about a 14% to 18% negative impact on slaughter cattle prices, which would drop them to the mid $70s/cwt.

Feeder cattle prices follow expected slaughter cattle prices. Futures prices for the summer months dropped by $5 per hundredweight as of Jan. 5. The predicted feeder cattle impact would be a $10 per cwt. negative impact on prices for 700 to 800 pound feeders, with a greater impact on lighter calves. Feeder cattle markets are still uncertain, but seem to be settling at levels about $5 to $10 per cwt. lower than mid December.

What is happening to beef demand?

U.S. research and the Canadian experience suggest that there will not be a great negative consumer response. Initial retail market surveys seem to support this analysis, although some categories of consumer are changing their eating habits. One consumer survey suggested that as many as one-third of consumers were changing their beef consumption, however, if this includes groups already at the low beef consumption level, the total impact will be small.

Per capita beef consumption is likely to increase this year. If retail prices follow the wholesale trends, many consumers will respond to the “bargains” and increase their purchases.

What are the longer term prospects?

Since the trade embargoes caused the greatest negative price impact, reopening doors to U.S. exports is the most important factor in a price recovery. Other lasting impacts will be the uncertainty of consumer demand and production. In the next few months, the supply of beef will be very uncertain. Feedlots may hold back on production. However, if they expect price recovery, they will hold cattle longer and the cattle will go to market at heavier weights.

From the long term view of cow-calf operations, the BSE case may be a positive factor since it is likely to halt any expansion of the cow herd. The result will be a longer period of comparatively tight supplies.

What is being done in response to the recent incidence of BSE in the US?

Many activities were already on-going that will have an impact on our response to BSE. The primary change is that the time-line for implementation of these activities will likely be moved up in response to BSE. The primary focus is around development and implementation of an animal identification and tracking program. Specific activities within this focus include source verified to farm of origin CPH 45 feeder cattle sales; electronic identification and tracking of feeder cattle through the feed-yard and to the packing plant as well as building and maintaining a data base of health and carcass quality for Kentucky feeder cattle.

How might a national ID system work?

The system outlined in the U.S. Animal Identification Plan (USAIP) would require producers to identify livestock with an electronic ID tag the first time they move in commerce. This movement would trigger the calculation of a premise ID number for the person or entity marketing the animal or animals. This premise ID would then become the sole identity of that entity in a database for traceability. Sale barns and marketers of livestock would be required to record the dates and locations that livestock move in commerce. The state veterinarian has the responsibility of defining a premise and providing access to the system to calculate the numbers. Animals that move in contained groups that stay intact from original owner to harvest can be identified with a lot number (probably hogs and poultry but could include retained ownership and contract cattle).

What is the proposed timeline for implementation of a national ID system?

The USAIP sets out a timeline that was formulated prior to the BSE case. It states that states should have a program for administering the allocation of premise ID’s by July 2004. The timelines are somewhat species specific from that point forward. In cattle that move in interstate commerce, identification would begin in July of 2005 with intrastate movements being tagged by July 2006. It is a widely held belief that these target dates will likely move closer in light of the BSE case in Washington State. In Kentucky we have the ability to put producers into a voluntary system that will begin to compile historic information on livestock ahead of a federally mandated program. This is the major focus of the Kentucky Beef Network.

What is EID?

Electronic Identification is a system of incorporating a radio frequency chip (RFID) into the ear tags of livestock. This chip, when read by a scanner, gives out a 15 digit number. The chip does not store any information other than the number and only sends the number when contacted by a reader. There are two tag technologies on the market right now, full and half duplex. Each has its own uses and capabilities. Scanners come in many forms from handheld wands to walk thru loop units. The best comparison to EID technology is the bar-code technology used in retail stores. The bar-code does not store any information but serves as an identity for that product in the computer system that operates the inventory management and pricing systems in the store.

What is premise ID?

In the USAIP the cornerstone of an animal ID program is a premise ID number that would be assigned to each person or location (entity) marketing livestock. The number would be a random number with no particular coding or means of using it for traceability by itself. The number would be assigned to the entity after collection of basic contact and location information upon the first entry to the market place. Producers will be able to preregister for premise IDs through their state veterinarian. The state veterinarian has the authority to define a premise for that state and has the responsibility to either administer a system for assigning these numbers or contracting with someone to provide that service.

What can I do now to prepare for national ID?

Be prepared to tag your livestock on the farm before they go to market. If you choose not to do so you will most certainly be charged a fee for applying tags. Most importantly, producers need to begin to keep records if they do not already. The KY BQA manual along with the IRM records books are good sources for suggested records forms (cattle movement, birth dates, basic production and health information will be important). Above and beyond the issue of having records for traceability, it is commonly thought that the ability of a database system to share source verification information will create an environment for value added marketing for those practicing good management.

Will the way we market cattle change as a result of a national ID program?

It is commonly held that livestock will need to be tagged with an EID before being sold or tagged at the markets. The responsibility for tagging or paying for the service of tagging resides with the person marketing the cattle. There is no reason to think that the manner in which we market livestock will change or even slow down as long as producers will complete some basic tasks to pull the responsibility of tagging out of the markets. You will see RFID scanners in place in the markets and on many farms to record the numbers as livestock move. The possibility exists that because of individual identification, markets may well be in a position to provide producers with individual data on the livestock as the data is collected for traceability. There will be some cost associated with collection and handling of the data collected. Current estimates are that an EID system will probably add $2-3/head to the marketing cost on cattle if producer will tag them on farm and as much as $5-6/head if they have to be tagged in the markets.

Who owns the data in this database?

The KBN database is producer owned and privately operated for a reason – the data can be protected and access to it limited. You own the data that is entered on your animals and have the authority to open or limit access to that data at your discretion with the exception of an incident of a request for traceability from the USDA resulting from a case of animal disease. This traceability function would apply once a mandated national system is in place. Until that time you can use the system to accumulate data for your benefit and verification.

Can I be proactive and voluntarily begin an ID program now to accumulate data to protect my operation?

Yes, when premise ID’s become available in the near future, apply to the State Veterinarian’s office for and receive a premise ID number. Next, contact the Kentucky Beef Network and purchase electronic tags for insertion into your cattle. The charge for voluntarily identifying livestock and their entry into the KBN database is $3/head including the tag. The KBN and others working with them can collect information for cattle moving in purebred or special feeder sales. Cattle moving off the farm in load lots can also be tracked. Value Added Target Marketing, a cooperative effort between UK Extension and the KBN, will assist in obtaining data on your cattle from the feed-yard and packer. Beginning to gather this information now, in advance of a national program, may reap significant benefits to Kentucky producers.

Additional Links Related to BSE

USDA Animal and Plant Health Inspection Service

Department of Health and Human Services Center for Disease Control and Prevention

US Food and Drug Administration


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