U of A led research suggests new culprit in mad cow disease The devastating disease can be caused without the presence of infectious prions?
U of A-led research suggests new culprit in mad cow disease
The devastating disease can be caused without the presence of infectious prions, study shows.
DECEMBER 01, 2025 BY BEV BETKOWSKI
A groundbreaking study led by U of A researchers shows that bovine spongiform encephalopathy, or “mad cow disease,” may not only be caused by misfolded proteins in the brain — a discovery that could point to new ways to prevent the disease. (Photo: Getty Images)
Groundbreaking research led by the University of Alberta challenges the belief that mad cow disease is caused only by misfolded proteins — a discovery that sheds new light on the devastating outbreak in the United Kingdom 40 years ago and provides new hope for prevention.
The study shows for the first time that such prion-like brain diseases can be triggered without the presence of infectious prions. Prion disease occurs when normal proteins in the brain misfold into infectious, abnormal proteins.
Instead, chronic inflammation caused by a powerful bacterial endotoxin called lipopolysaccharide (LPS) was identified as a culprit that can independently trigger brain damage resembling prion disease.
“This fundamentally challenges the prevailing theory that these types of brain diseases are only about prions or similar misfolded proteins,” says Burim Ametaj, a nutritional immunobiologist in the Faculty of Agricultural, Life & Environmental Sciences and lead author on the study.
The research revealed more of a multifaceted process behind that neurodegeneration, showing that inflammation weakens the brain’s defences first, overwhelming cells. Proteins could then start misfolding and the immune system over-reacts, causing more damage.
“All three processes feed into each other, which means we need to target inflammation and immune health, not just the misfolded proteins.”
New clue to a devastating outbreak The discovery suggests that endotoxins in the animal-derived feed offered to cattle may have contributed to the bovine spongiform encephalopathy (BSE), or mad cow disease, crises in the United Kingdom, Ametaj says.
The outbreaks devastated the livestock industry in the 1980s and 1990s, resulting in the deaths of more than 160 people who’d eaten infected beef, and the slaughter of more than four million cattle.
The study provided striking evidence that LPS alone, administered under the skin, caused spongiform brain symptoms in 40 per cent of mouse models — a “holey” appearance in the tissues seen in BSE and related diseases. When LPS was combined with lab-created misfolded proteins, that number rose to 50 per cent. In both scenarios, this Alzheimer-like damage happened even when the naturally occurring infectious prion responsible for BSE was absent.
The research also showed that when an actual prion disease such as BSE is present, inflammation caused by LPS dramatically worsens damage to the brain, resulting in 100 per cent mortality within 200 days of infection.
This fundamentally challenges the prevailing theory that these types of brain diseases are only about prions or similar misfolded proteins.
Burim Ametaj
Burim Ametaj (Photo: John Ulan) The new findings could offer insight into why there were many more BSE cases in England and Wales than in Scotland, based on the procedures rendering plants used to make livestock feed, Ametaj says.
“Plants in England and Wales removed a critical substance called hexane from the production process to cut costs. This solvent was essential not only for fat extraction, but also for dissolving and removing LPS from the meat-and-bone meal.
“In contrast, Scottish rendering plants retained the hexane step and potentially because of that, had markedly fewer BSE cases — a fact long known but never systematically explained,” he notes.
The study measured LPS in meat-and-bone meal, blood meal and tallow — the feed implicated in BSE — and confirmed high levels of contamination. Combined with chronic exposure to such feed, predisposing conditions in dairy cows induced by high-grain diets immediately postpartum, and by an increased “leaky gut”, can trigger systemic inflammation and could contribute to the development of neurodegenerative disease, Ametaj notes.
“This suggests that excluding the hexane step left contaminated feed that could independently trigger neurodegeneration, explaining why the BSE epidemic followed the geographic pattern it did.”
Implications for human diseases The research may hold major implications for feed and livestock producers, Ametaj adds.
“The lessons from the BSE outbreaks about proper rendering processes and better feed safety remain relevant today. The prevention path is clear: maintain endotoxin-removal processing steps and monitor contamination. Any industrial feeding system that doesn’t control this could create conditions for neurodegeneration.”
He’s also “cautiously optimistic” about how the findings could help prevent or treat human diseases such as Alzheimer's and Parkinson’s.
“It opens up an entire anti-inflammatory medicine toolkit. Bacterial endotoxins have been found in the brains of Alzheimer’s patients, so risk factors that reduce dementia — exercise, anti-inflammatory diets, gut health, metabolic health — might work partly by reducing endotoxin burden.
“These diseases are complex, but if endotoxin exposure contributes to even 20 to 30 per cent of cases, controlling this modifiable risk factor could spare millions of people,” Ametaj adds. “We might prevent some neurodegenerative diseases the way we prevent heart disease, by managing inflammatory risk factors throughout life.
“In a field where there’s been little hope, that matters.”
Study co-authors include former master’s student Seyed Ali Goldansaz, postdoctoral fellows Dagnachew Hailemariam and Elda Dervishi, U of A scientists David Wishart and David Westaway and his team, and researchers from the University of Warmia and Mazury in Poland.
The study was funded by the former Alberta Livestock and Meat Agency and the Alberta Prion Research Institute.
https://www.ualberta.ca/en/folio/2025/12/u-of-a-led-research-suggests-new-culprit-in-mad-cow-disease.html
27 June 2025
Lipopolysaccharide and Recombinant Prion Protein Induce Distinct Neurodegenerative Pathologies in FVB/N Mice
Seyed Ali Goldansaz1,2,† , Dagnachew Hailemariam1,† , Elda Dervishi1 , Grzegorz Zwierzchowski1,3 , Roman Wójcik4 , David S. Wishart5,6 and Burim N. Ametaj1,*
1 Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada 2 Sustainable Livestock Systems Branch, Sustainable Agri-Food Sciences Division, Agri-Food & Biosciences Institute, Hillsborough BT26 6DR, UK 3 Faculty of Biology and Biotechnology, University of Warmia and Mazury, 1a Oczapowskiego Str., 10-719 Olsztyn, Poland 4 Faculty of Veterinary Medicine, University of Warmia and Mazury, 1a Oczapowskiego Str., 10-719 Olsztyn, Poland
Show more Int. J. Mol. Sci. 2025, 26(13), 6245; https://doi.org/10.3390/ijms26136245 This article belongs to the Special Issue Advanced Research on Immune Cells and Cytokines (2nd Edition)
Version Notes
Order Reprints Abstract
Prion diseases are classically attributed to the accumulation of protease-resistant prion protein (PrPSc); however, recent evidence suggests that alternative misfolded prion conformers and systemic inflammatory factors may also contribute to neurodegeneration. This study investigated whether recombinant moPrPRes, generated by incubating wild-type mouse PrPC with bacterial lipopolysaccharide (LPS), can induce prion-like disease in FVB/N female mice, whether LPS alone causes neurodegeneration, and how LPS modulates disease progression in mice inoculated with the Rocky Mountain Laboratory (RML) strain of prions. Wild-type female FVB/N mice were randomized into six subcutaneous treatment groups: saline, LPS, moPrPRes, moPrPRes + LPS, RML, and RML + LPS. Animals were monitored longitudinally for survival, body weight, and clinical signs. Brain tissues were analyzed histologically and immunohistochemically for vacuolar degeneration, PrPSc accumulation, reactive astrogliosis, and amyloid-β plaque deposition. Recombinant moPrPRes induced a progressive spongiform encephalopathy characterized by widespread vacuolation and astrogliosis, yet with no detectable PrPSc by Western blot or immunohistochemistry. LPS alone triggered a distinct neurodegenerative phenotype, including cerebellar amyloid-β plaque accumulation and terminal-stage spongiosis, with approximately 40% mortality by the end of the study. Co-administration of moPrPRes and LPS resulted in variable regional pathology and intermediate survival (50% at 750 days post-inoculation). Interestingly, RML + LPS co-treatment led to earlier clinical onset and mortality compared to RML alone; however, vacuolation levels were not significantly elevated and, in some brain regions, were reduced. These results demonstrate that chronic endotoxemia and non-infectious misfolded PrP conformers can independently or synergistically induce key neuropathological hallmarks of prion disease, even in the absence of classical PrPSc. Targeting inflammatory signaling and toxic prion intermediates may offer novel therapeutic strategies for prion and prion-like disorders.
Keywords: recombinant prion protein; lipopolysaccharide; cofactor; neurodegeneration; prion disease
https://www.mdpi.com/1422-0067/26/13/6245
***>
If this study holds true, Spontaneous BSE would be the cattle industry worse case scenario nightmare imho…terry
===>
“The research also showed that when an actual prion disease such as BSE is present, inflammation caused by LPS dramatically worsens damage to the brain, resulting in 100 per cent mortality within 200 days of infection.
This fundamentally challenges the prevailing theory that these types of brain diseases are only about prions or similar misfolded proteins.
Burim Ametaj (Photo: John Ulan) The new findings could offer insight into why there were many more BSE cases in England and Wales than in Scotland, based on the procedures rendering plants used to make livestock feed, Ametaj says.
“Plants in England and Wales removed a critical substance called hexane from the production process to cut costs. This solvent was essential not only for fat extraction, but also for dissolving and removing LPS from the meat-and-bone meal.
“In contrast, Scottish rendering plants retained the hexane step and potentially because of that, had markedly fewer BSE cases — a fact long known but never systematically explained,” he notes.
The study measured LPS in meat-and-bone meal, blood meal and tallow — the feed implicated in BSE — and confirmed high levels of contamination. Combined with chronic exposure to such feed, predisposing conditions in dairy cows induced by high-grain diets immediately postpartum, and by an increased “leaky gut”, can trigger systemic inflammation and could contribute to the development of neurodegenerative disease, Ametaj notes.
“This suggests that excluding the hexane step left contaminated feed that could independently trigger neurodegeneration, explaining why the BSE epidemic followed the geographic pattern it did.”
Implications for human diseases The research may hold major implications for feed and livestock producers, Ametaj adds.
“The lessons from the BSE outbreaks about proper rendering processes and better feed safety remain relevant today. The prevention path is clear: maintain endotoxin-removal processing steps and monitor contamination. Any industrial feeding system that doesn’t control this could create conditions for neurodegeneration.”
<***
Something to ponder!…terry
***>
“In the United Kingdom there is much concern for a specific continuous rendering technology which uses lower temperatures and accounts for 25 percent of total output. This technology was originally designed and imported from the United States. However, the specific application in the production process is _believed_ to be different in the two countries.”
“The application of solvent in the production process requires an additional reheating of product in order to burn off any remaining solvent residues. Whether it is the application of solvent or the reheating of product that may reduce any potential infectivity is uncertain. If all mature sheep meat and bone meal were fed to dairy cows it would amount to 3.4 pounds per cow per year in the United Kingdom and 2.8 ounces per cow in the United States.”
I remember back in 2000…
Singeltary 2000
BMJ 2000; 320 doi: https://doi.org/10.1136/bmj.320.7226.8/b (Published 01 January 2000) Cite this as: BMJ 2000;320:8
02 January 2000 Terry S Singeltary retired
Rapid Response:
U.S. Scientist should be concerned with a CJD epidemic in the U.S., as well...
In reading your short article about 'Scientist warn of CJD epidemic' news in brief Jan. 1, 2000. I find the findings in the PNAS old news, made famous again. Why is the U.S. still sitting on their butts, ignoring the facts? We have the beginning of a CJD epidemic in the U.S., and the U.S. Gov. is doing everything in it's power to conceal it.
The exact same recipe for B.S.E. existed in the U.S. for years and years. In reading over the Qualitative Analysis of BSE Risk Factors-1, this is a 25 page report by the USDA:APHIS:VS. It could have been done in one page. The first page, fourth paragraph says it all;
"Similarities exist in the two countries usage of continuous rendering technology and the lack of usage of solvents, however, large differences still remain with other risk factors which greatly reduce the potential risk at the national level."
Then, the next 24 pages tries to down-play the high risks of B.S.E. in the U.S., with nothing more than the cattle to sheep ratio count, and the geographical locations of herds and flocks. That's all the evidence they can come up with, in the next 24 pages.
Something else I find odd, page 16;
"In the United Kingdom there is much concern for a specific continuous rendering technology which uses lower temperatures and accounts for 25 percent of total output. This technology was _originally_ designed and imported from the United States. However, the specific application in the production process is _believed_ to be different in the two countries."
A few more factors to consider, page 15;
"Figure 26 compares animal protein production for the two countries. The calculations are based on slaughter numbers, fallen stock estimates, and product yield coefficients. This approach is used due to variation of up to 80 percent from different reported sources. At 3.6 million tons, the United States produces 8 times more animal rendered product than the United Kingdom."
"The risk of introducing the BSE agent through sheep meat and bone meal is more acute in both relative and absolute terms in the United Kingdom (Figures 27 and 28). Note that sheep meat and bone meal accounts for 14 percent, or 61 thousand tons, in the United Kingdom versus 0.6 percent or 22 thousand tons in the United States. For sheep greater than 1 year, this is less than one-tenth of one percent of the United States supply."
"The potential risk of amplification of the BSE agent through cattle meat and bone meal is much greater in the United States where it accounts for 59 percent of total product or almost 5 times more than the total amount of rendered product in the United Kingdom."
Considering, it would only take _one_ scrapie infected sheep to contaminate the feed. Considering Scrapie has run rampant in the U.S. for years, as of Aug. 1999, 950 scrapie infected flocks. Also, Considering only one quarter spoonful of scrapie infected material is lethal to a cow.
Considering all this, the sheep to cow ration is meaningless. As I said, it's 24 pages of B.S.e.
To be continued...
Terry S. Singeltary Sr. Bacliff, Texas USA
Competing interests: No competing interests
https://www.bmj.com/rapid-response/2011/10/28/us-scientist-should-be-concerned-cjd-epidemic-us-well
Published: 30 June 2015
Transmission of scrapie prions to primate after an extended silent incubation period
***Moreover, sporadic disease has never been observed in breeding colonies or primate research laboratories, most notably among hundreds of animals over several decades of study at the National Institutes of Health25, and in nearly twenty older animals continuously housed in our own facility.***
Even if the prevailing view is that sporadic CJD is due to the spontaneous formation of CJD prions, it remains possible that its apparent sporadic nature may, at least in part, result from our limited capacity to identify an environmental origin.
https://www.nature.com/articles/srep11573
https://www.ars.usda.gov/research/publications/publication/?seqNo115=361032
O.05: Transmission of prions to primates after extended silent incubation periods: Implications for BSE and scrapie risk assessment in human populations
*** We recently observed the direct transmission of a natural classical scrapie isolate to macaque after a 10-year silent incubation period,
***with features similar to some reported for human cases of sporadic CJD, albeit requiring fourfold long incubation than BSE. Scrapie, as recently evoked in humanized mice (Cassard, 2014),
***is the third potentially zoonotic PD (with BSE and L-type BSE),
***thus questioning the origin of human sporadic cases.
==============
PRION 2015 CONFERENCE
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5019500/
Qualitative Analysis of BSE Risk Factors in the United States
From: Terry S. Singeltary Sr.
Subject: Qualitative Analysis of BSE Risk Factors in the United States (part 1)
Date: February 13, 2000 at 3:37 pm PST
Qualitative Analysis of BSE Risk Factors in the United States (part 1)
Contents; Executive Summary................1 Introduction.....................2 Sheep Population and Practices...3 Cattle Inventories and Practices.8 Slaughter Industry..............13 Rendering Industry..............15 Feed Industry...................19 Qualitative Assessment..........23 List of Figures.................25
__________________________________________________________________
Executive Summary
Since 1986, Bovine Spongiform Encephalopathy (BSE) has been diagnosed in over 21,000 cattle, 0.5 percent of the United Kingdom adult cattle population or 9-10 percent of the beef and dairy operations. Almost exclusive to the United Kingdom, new cases currently average 325-350 per week. BSE is an unconventional infectious virus. Current hypotheses suggest that an increase in the exposure of cattle to the sheep scrapie agent via ruminant derived proteins in feedstuffs have led to a detectable incidence of the disease. While BSE is not known to exist in the United States, it is of concern when considering that receipts to farmers from cattle, sheep and related products are roughly $60 billion dollars per year and feed expenses are over $20 billion per year. This report contrasts the United States and United Kingdom sheep and cattle demographics along with characteristics of the slaughter, feed, and rendering industries. This contrast is followed by an analysis of major similarities and differences in order to arrive at a qualitative assessment of the risk of BSE at the national level.
Within the United Kingdom, a number of key related factors provide possible explanations for a change in contact of cattle to sheep-derived proteins. Sheep numbers increased by 12 million head over the last decade allowing a probable increase in the prevalence of scrapie infected flocks. Increased sheep numbers led to a larger amount of sheep raw material from both fallen and slaughter stock in animal products. In addition, the adoption of a newer continuous rendering technology process along with a drastic reduction in hydrocarbon solvents have led to changes in the manufacturing processes.
Similarities exist in the two countries usage of continuous rendering technology and the lack of usage of solvents, however, large differences still remain with other risk factors which greatly reduce the potential risk at the national level.
The United Kingdom has 4 times as many sheep and 3 times as many ewes on a land mass slightly smaller than the State of Oregon. The higher density of sheep to land along with substantial movement of sheep is conducive to facilitating the spread of scrapie across the sheep population. In the United States, 80 percent of the sheep are in the 17 western States. With predators such as coyotes and large rangeland operations, removal of fallen and diseased sheep stock to be rendered is less complete compared to the specialized United Kingdom "knacker" industry.
The ratio of all sheep to all cattle is 32 times greater in the United Kingdom. Likewise, the ratio of all mature sheep to all milk cows is 10 times larger. Sheep in the United Kingdom account for 14 percent of raw rendering material versus 0.6 percent in the United States. This computes to 3.4 pounds per dairy cow in the United Kingdom versus 2.8 ounces per head in the United States.
Almost all cases have been in dairy herds with 89 percent of cases in cows 4 years and older. In the United States, 53 percent of all dairy cows are less than 4 years of age. In the United Kingdom, 70 percent of all dairy cows are older than 4 years. The United States feeds 41 pounds per 100 pounds of milk produced versus 21 pounds in the United Kingdom. However, for each pound of mature sheep meat and bone meal produced, 17 tons of dairy concentrate are fed in the United States versus 0.4 tons in the United Kingdom. The United States grows an abundance of plant based proteins. The United Kingdom has traditionally imported some 500-600,000 tons of soybeans. Moreover, the portion of animal proteins used as a percent of all other major feed proteins is 6-7 percent greater in the United Kingdom.
While this qualitative analysis suggests the potential risk of BSE at the national level is substantially less, no analysis is made of the variation in the levels of risk across geographic areas of production. Of consideration are factors such as the concentration of mature sheep slaughter and the proximity of rendered products from mature sheep offal to dairy populations. A more indepth quantitative analysis of these and other risk factors are contained in the APHIS:VS Ouantitative Risk Assessment of BSE in the United States.
Qualitative Analysis of BSE Risk Factors - 1
_______________________________________________________________
Introduction
Bovine Spongiform Encephalopathy (BSE) is an unconventional infectious virus. Virtually all cases have been in the United Kingdom with new cases currently averaging 325-350 per week. The current hypotheses suggest that an increase in the exposure of cattle to the scrapie agent via ruminant derived proteins in feedstuffs have led to a detectable incidence of the disease. Key related factors provide possible explanations for a change in the contact of cattle to sheep-derived protein. Sheep numbers increased in the last decade suggesting a probable increase in the prevalence of scrapie infected flocks.
Increased sheep numbers led to a larger amount of sheep raw material from both slaughter and fallen stock in rendered animal products. Concurrently, cattle numbers trended down decreasing their contribution to total rendered product. The adoption of a newer, continuous rendering process allowed for lower temperature and/or shorter periods of time to be used in the manufacturing process. In addition, the decline in the usage of hydrocarbon solvents and the associated heat treatment used in this process potentially resulted in increased survival of the infectious agent.
The qualitative analysis presented in this report compares and contrasts the United States and United Kingdom sheep and cattle demographics along with characteristics of the slaughter, feed, and rendering industries. Comparisons between the two countries are presented at the aggregate or national level. For each sector, background and demographic information is given followed by a section outlining key differences between the two countries as it relates to BSE. This is followed by a qualitative assessment which syntheses the major similarities and differences in order to arrive at a broad estimate of risk at the national level.
Qualitative Analysis of BSE Risk Factors - 2
__________________________________________________________________
Sheep Population and Practices
For the past 10 years, the sheep populations in the two countries have moved inversely. From a peak of 49 million head in 1942, United States' sheep inventories have trended down (Figure 1). Contributing factors include a shrinking consumer base, a higher relative price compared to other meats, wide price variations from small changes in supply, and a dwindling supply of experienced labor. Based on location and production practices, United States sheep operations can be geographically divided into two categories. First, 80 percent of all sheep are located in the 17 western States (Figure 2). Mostly white-faced breeds, these operations can contain both sheep and cow-calf enterprises. Available range lands constitute a major feed stock. The density of sheep to usable land is low, computed at 1 animal per 10 acres. Second, of the remaining 20 percent of sheep, many are in the upper Midwest. Often small and part-time operations, many of the sheep are black-faced breeds. The upper Midwest contains some of the highest densities of sheep to usable land at 1 animal per 3 acres (Figure 3).
The United Kingdom sheep population is increasing from a 1978-80 average of 30.4 million head to a 1989 inventory level of 42.9 million head (Figure 4). While sheep meat consumption is one-half the level of 20 years ago, less imports and production incentives have acted to increase domestic production. Moreover, the imposition of milk quotas coupled with a price support system whereby one-third of revenues are from non-market sources have boosted the number of combined sheep and dairy operations. Substantial movement of sheep occurs with animals, including ewes, transported from the highlands of Northern England and Scotland to the lowlands further south. In addition there is significant buying, selling, and transportation of sheep to arbitrage price differentials across areas.
Farm Size and Concentration
Although each country has roughly 92,000 sheep operations, the United Kingdom contains 4 times as many sheep with the distribution of sheep across different herd sizes varying significantly (Figure 5). Herd size distribution is even more pronounced in the United States where 50 percent of the sheep operations are of the smallest size category, 1-24 head, which accounts for only 4.5 percent of all sheep. Conversely, only 2 percent of the United States sheep operations are of the largest size category, 1000 + head, which accounts for 51 percent of all sheep. This compares with 55 percent of the United Kingdom sheep operations having between 100 and 1000 head and accounting for 47 percent of all sheep.
Scrapie Disease
Both countries have taken different approaches to sheep scrapie disease. The United States has employed indemnity payments and encouraged reporting as control measures. Scrapie has been reported in 35 States with most of the reported cases in the black-faced breeds (Figures 6 and 7). The reporting of scrapie has been notably influenced by the real (inflation adjusted) value of the indemnity payment (Figure 8). The 1980-90 cumulative reported incidence of scrapie is 7.5 flocks per 1000 flocks, with substantial intrastate variation.
With scrapie endemic for at least two hundred years, the United Kingdom has no national movement to encourage the control or reporting of the disease. Even though prevalence estimates are suspect, the results suggest that scrapie is common within all breeds. Further, the total number of all cases is substantially greater in the United Kingdom versus the United States.
Qualitative Analysis of BSE Risk Factors - 3 __________________________________________________________________
Sheep Population and Practices
Key Factors
During the 1980's, the two countries' sheep populations moved inversely. The United Kingdom now has 4 times as many sheep and lambs and more importantly about 3 times as many mature sheep or sheep greater than 1 year old (Figure 9). This increase in the number of sheep in the United Kingdom allowed for a probable increase ia the prevalence of scrapie flocks. The result was more infected sheep material from slaughter and dead stock available for usage in animal protein products.
Unlike the United States where 50 percent of the sheep are on 2 percent of the farms, the United Kingdom has 47 percent of the sheep on one-half of the farms. This supports a more active market to buy, sell, and move stock sheep across the United Kingdom. This also facilitates a potential spread of scrapie across the population.
U.S. Sheep Inventory 1974 - 1990-
Thousands of animals
Figure 1
20,000
15,000
10,000
5,000
1975 1980 1985 1990.
[[[chart above, and map below not available to scan and paste...TSS]]]
Number of Sheep and Lambs by State - 1990 U.S. total = 11,365.4 (Thousands)
Figure 2 MAP [[[not available...but shows Texas having the largest number, with the map showing it being the only state completely blackened in. It is measured in 1,000's of head, with the completely blackened area being > 1,000...TSS]]]
Source: USDA/NASS USDA:APHIS:VS -- Source: USDA/NASS *Preliminary
Qualitative Analysis of BSE Risk Factors - 4 __________________________________________________________________
Sheep Population and Practices
U.S. SHEEP - COUNTY POP. DIST. 1987 (ANIMALS / ACRE)
Figure 3 [[[MAPS AND CHARTS NOT AVAILABLE...TSS]]]
U.K. Sheep Inventory 1978 - 1989
Thousands of Animals
Figure 4 [[[NOT AVAILABLE...TSS]]]
Source: Agricultural Statistics, United Kingdom
Figure 5 U.K. & U.S. Comparison of Sheep Numbers and Farms by Herd Size - 1989
Herd Size % of Sheep % of Farms (# head) U.S. U.K. U.S. U.K.
1-24 4.5 .3 50.0 11.0
25-99 13.5 2.7 34.0 21.0
100-299 14.0 11.4 10.0 27.0
300-999 16.7 35.4 4.0 28.0
1000 + 51.3 50.2 2.0 13.0
USDA:APHIS:VS Source: U.S. Ag Census U.S. Ag Statistics MAFF, United Kingdom
Qualitative Analysis of BSE Risk Factors - 5 __________________________________________________________________
Sheep Population and Practices
Cumulative Incidence of Scrapie in Sheep 1980-1990
Figure 6 Infected Scrapie Flocks/10,000 Ewes
0 to 0.016
0.017 fo 0.23
0.24 to 2.63
2.64 to 20.45
[[[Map Not Available...TSS]]]
U.S. Breed Distribution of Sheep Scrapie Reported (1947-1990)
Figure 7 [[[Chart not available...TSS]]]
Suffolk---------84.%
Hampshire--------6.%
Cheviots---------2.%
Crossbreds-------1.%
Southdowns-------0.5%
Montadales-------0.25%
Finns------------0.1%
Merino-----------0.1%
Cottswold--------0.1%
Corriedale-------0.1%
Dorset-----------0.1%
Rambouillet------0.1%
Breed not listed-5.7%
USDA:APHIS:VS
Qualitative Analysis of BSE Risk Factors - 6 __________________________________________________________________
Sheep Population and Practices
Effect of Indemnity on U.S. SCRAPIE Reporting
Scrapie Flocks Reported Indemnity Payment
Figure 8 [[[Not Available...TSS]]]
Figure 9 Sheep & Lamb Inventories - 1989 (thousand head)
U.S. U.K. U.K./U.S.
(January) (June)
All Sheep & Lambs 10,858 42,885 4.0
Sheep > 1 year 7,521 21,284 2.8
USDA:APHIS:VS Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Qualitative Analysis of BSE Risk Factors - 7 __________________________________________________________________
Cattle Inventories and Practices
Similar to sheep, cattle production has varied significantly within the two countries. Although the number of cattle have declined by 2 million head per year since 1975, the United States still maintains more than 8 times as many cattle (Figures 10 and 11) as the United Kingdom (Figure 12). Concentrate feeding remains an important practice with 75 percent of all cattle slaughtered having spent time in a feedlot. At 12 million head, the United Kingdom beef numbers have declined by 1.5 million head in the last 10 years. Unlike the United States where per capita beef consumption has dropped almost 6 pounds since 1987, the United Kingdom household consumption has remained relatively unchanged and reports of drastic decline in beef demand have been exaggerated.
The number of dairy cows in both countries have declined but for different reasons. At 10.1 million head versus 2.9 million head, the United States has 3.5 times more cows. In the United States, per cow and total milk production have more than offset the decline in cow numbers (Figures 13 and 14). Milk support policies, genetic advances and more intensive management have encouraged the culling of older cows and the feeding of concentrates in the United States (Figure 15). Compared to the United Kingdom, dairy cows in the United States are on average 1.3 years younger, produce 5,000 more pounds of milk and consume 1.8 additional tons of concentrate feeds (Figure 16). Cow numbers in the United States are disproportionate to the herd size distributions. The smallest herd size category, 1-29 head, contains 45 percent of the farms but only 7 percent of the cows. The highest category, 200 + head, contains only 2 percent of the farms but 24 percent of the cows (Figure 16).
The decrease in the United Kingdom dairy cow numbers of about 400,000 over the last ten years has been notably influenced by the imposition of dairy milk production quotas. A slight gain in per cow milk production has not been sufficient to compensate for the decline in cow numbers causing total milk production to decline. Unlike the United States, dairy, beef, and/or sheep are often combined operations with little concentrate fed. Roughly two-thirds of eventual cattle slaughter originate from dairy stock and approximately 5-7 percent of cows in cow-calf herds are culled dairy cows. Milk quotas have boosted the number of sheep raised with dairy. For England and Wales, 72 percent of sheep operations contain 81 percent of all sheep and 50 percent of all cattle (Figure 17). Compared to the United States, herd size distribution is more proportional across herd size classes in the United Kingdom.
Key Factors
The distribution by breed and functional type (Figure 18) indicates that 98 percent of all reported BSE cases in the United Kingdom have been in dairy herds. The proportion of cases is similar to the breed distribution and suggests no predisposition by breed to disease.
Compared to the United Kingdom, United States dairy production is more intensive, using less grass and more concentrate feeds. Concentrates fed per cow ranges from 1.9 tons to over 5 tons. The sourcing and relative quantities of protein components in concentrates varies considerably depending on geographic location and prices of substitutes.
Of critical importance are the relative age distributions. Fifty-three percent of the United States dairy cows are less than 4 years of age, whereas, 70 percent of the United Kingdom's dairy cows are greater than 4 years and have accounted for 89 percent of the BSE reported cases. In 1989, the occurrence of BSE in cows 2-3 years of age was approximately 12 cases per 10,000 cows (Figure 19). For cows greater than 4 years, the range was from 59 cases per 10,000 cows for age 7 and older to 288 cases per 10,000 for cows of age 5.
Qualitative Analysis of BSE Risk Factors - 8 ___________________________________________________________________
Cattle Inventories and Practices
At 329 affected herds per 10,000 herds, herds Containing 200 or more head (Figure 16) are at greatest risk of BSE in the United Kingdom. This compares with 14 herds per 10,000 herds for herds of less than 50 head. The United Kingdom has 9 percent of all dairy cows in the largest herd size category versus 24 percent in the United States.
The ratio of all sheep to all catfie is 32 times greater in the United Kingdom versus the United States. Because of the extended incubation period, sheep greater than 1 year of age are of primary concern for scrapie disease. In this case, the ratio of all sheep greater than 1 year to all beef and milk cows is 29 times greater in the United Kingdom. For mature sheep to milk cows, the ratio is 10 times greater in the United Kingdom (Figure 20).
Total U.S. Cattle Inventory 1974 - 1990
Figure 10 Million Head
1975-132,000,000
1980-111,000,000
1985-110,000,000
1990-99,000,000*
Source: USDA:NASS USDA:APHIS:VS *Partial Estimate
U.K. Beef & Dairy Cattle Inventory 1978-1989
Thousands of Animals
Figure 11 [[[Not Available...TSS]]]
Source: Agricultural Statistics United Kingdom USDA:APHIS:VS
Qualitative Analysis of BSE Risk Factors - 9 _________________________________________________________________
Cattle Inventories and Practices
Cattle & Calf Inventories (thousand head) Figure 12 U.S. U.K. (1990) (1989)
All Cattle and Calves 99,337 12,016
Beef Cows 33,705 1,495
Milk Cows 10,149 2,867
Heifers, Steers, Bulls, and Calves 55,484 7,654
USD:APHIS:VS Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Figure 13 [[[Not Available...TSS]]]
Number of U.S. Milk Cows and Average per Cow Milk Production (1965-1989)
USDA:APHIS:VS Source: USDA:NASS
Figure 14 [[[Not Available...TSS]]]
Total U.S. Milk Production 1965 - 1989 Million Pounds USDA:APHIS:VS Source: USDA:NASS
Qualitative Analysis of BSE Risk Factors - 10 __________________________________________________________________
Cattle Inventories and Practices
Dairy Cow Inventories, Average Milk Production and Concentrate Fed
U,S. (1990) U,K. (1989)
Dairy Cows 10,149 2,867 (thousand head)
Figure 15 Average Milk Production (Ibs/yr) 14,244 9,448
Concentrate Fed (Ibs/yr) 5,800 2,180
USDA:APHIS:VS Source: Agricultural Statistics & MAFF, United Kingdom, U.S. Dept. of Agriculture
Comparison of Herds, Cows and U.K. BSE Cases by Herd Size - 1988
Figure 16 Herd Size U.S. U.K. U.K. BSE* (# of head) % herds % cows % herds % cows case herds/ 10,000 herds 1-29 45 7 27 6 14
30-49 23 18 23 15
50-99 23 32 34 39 72
100-199 7 19 14 30 193
200+ 2 24 2 9 329
*As of April 1988
USDA:APHIS:VS Source: Ag. Statistics United Kingdom The Veterinary Record (12/17/88) U.S. Dept. of Agriculture
Figure 17
Sheep and Cattle Operations U.S. U.K. (1988) (1989)
Number of Sheep Operations 92,489 91,296
Number of Cattle Operations 1,176,346 70,378
Number of Dairy Operations 202,068 47,935
Percent of Sheep Operations 58% 72%* with Cattle
Percent of all Sheep 59% 81%* within Combined Operations
Percent of all Cattle within Combined Operations 4.5% 50%*
*Data for England and Wales only.
Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Qualitative Analysis of BSE Risk Factors - 11 _________________________________________________________________
Cattle Inventories and Practices
U.K. Distribution of BSE Confirmed & Suspect Cases* by Breed & Functional Type
Figure 18
Breed Dairy Cows Beef Cows
Friesian/Holstein 662 0
Ayrshire/3/4 Ayshire 11 0
Guernsey/3/4 Guernsey 18 0
Hereford x Friesian 0 12
Devon x Frieslan 0 1
Jersey x Friesian 1 0
Shorthorn 1 0
Shorthorn x Danish Rd 1 0
Jersey 2 0
Charolais 0 1
-As of April 1988
USDA:APHIS:VS Source: MAFF, United Kingdom
Age Distribution of Dairy Cows U.K. Occurrence of BSE - 1989
Figure 19
U.K. BSE Occurrence Age Distribution (%) % of cases #cases per~ Age U.S. U.K. 10,000 cows
2 year old cows 31 10 .4 5
3 year old cows 23 20 11 7
4 year old cows 17 18 38 276
5 year old cows 12 16 35 288
6 year old cows 8 12 13 131
7+ year old cow 9 24 3 59
Average Age (years) 3.8 5.1
USDA:APHIS:VS Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Animal Populations
Figure 20
U.S. U.K. U.K./U.S. (1989)
Ratio of ALL SHEEP to ALL CATTLE .11 3.6 32.7
Ratio of ALL SHEEP to Milk Cows 1.1 15.0 13.6
Ratio of ALL SHEEP > lyr to ALL Beef & Milk Cows .17 4.9 28.8
Ratio of ALL SHEEP > lyr to ALL Milk Cows .74 7.4 10.0
USDA:APHIS:VS Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Qualitative Analysis of BSE Risk Factors - 12 _________________________________________________________________
Slaughter Industry
As expected, the United States slaughters and produces 10 times more cattle and meat as the United Kingdom (Figure 21). For sheep however, the United Kingdom slaughters 3.5 times as many animals and 5.5 times as many ewes. At 843 million pounds, total sheep slaughter is 2.5 times greater than in the United States (Figure 22). Moreover, the numbers do not reflect the 300 million tons of imports some of which are live animals from the Irish Republic for slaughter in the United Kingdom.
Key Factors
The structure of the United States slaughter industry is more specialized with a large portion of the total supply originating from plants customized for specific species. Of the 4,500 commercial slaughter plants in the United States, 97 percent of slaughter comes from 1,300 federally inspected plants. In the United Kingdom, there are approximately 700 slaughter plants with 200 plants accounting for 85 percent of the total slaughter. Although some plants are species specific, many plants accommodate sheep, cattle, and swine which reflects the fluid movement and sale of animals around the country. There are only some 50 plants which contain inspectors and are licensed for export.
In the United Kingdom, 60 percent of the sheep slaughter occurs in the last 2 quarters and 18 percent in the 2nd quarter. In the United States only slight variation occurs over the four quarters. Cattle slaughter across quarters is fairly constant for both countries.
Concentration at point of slaughter is more pronounced in the United States. In 1989, eleven plants, each of which slaughtered more than 100,000 head, accounted for over 80 percent of total lamb slaughter (Figure 23). Twenty-four plants, each of which slaughtered more than 3,000 head, accounted for over 80 percent of total slaughter of sheep greater than one year old.
U.S. & U.K. Sheep & Cattle Slaughter - 1989
Figure 21
U.S. U.K.
All Cattle Slaughtered (thousand head) 36,330 3,667 / Average Dressed Carcass Weight (lbs) 683 634 / Total Production (million lbs) 23,098 2,127
All Sheep Slaughtered (thousand head) 5,572 20,338 / Total production (million lbs) 348 843*
Ratio of Cattle to Sheep Slaughter (lb basis) 66 2.5
*Does not include live animals imported from Irish Republic for slaughter.
USDA:APHIS:VS Source: MAFF, United Kingdom U.S. Dept. of Agriculture
Qualitative Analysis of BSE Risk Factors - 13 __________________________________________________________________
Slaughter Industry
Number & Age of Sheep Slaughter 1989
Figure 22
U.S. U.K.
All Sheep Slaughter (thousand head) 5,572 20,338
Lamb Slaughter 5,225 18,398
Mature Sheep 347 1,940
Slaughter Ratio of Lamb to Ewe 15 9.5
Average Dressed Weights (lbs)
Lambs 58 40
Mature Sheep 64 47
Mature Sheep as a Proportion of Total Dressed Weight 6.8% 11.0%
USDA:APHIS:VS
1989 Geographic Distribution of Plants Accounting for 80 Percenf of Sheep & Lamb Slaughter
Figure 23 [[[Not Available...TSS]]]
Interesting though, the state of Texas shows mature sheep slaughter > 3,000 head and lamb slaughter > 100,000 head and mature sheep slaughter > 3,000 head...TSS]]]
USDA:APHIS:VS
Qualitative Analysis of BSE Risk Factors - 14
Rendering Industry
The rendering industries in both countries continue to undergo substantial structural adjustment. The current number of inedible renders in the United States is approximately 331, down from 990 in 1978. The decline of roughly 50 operations per year is attributable to several factors including changes in technology and slaughter industry practices. The older and more resource intensive batch rendering process is largely being replaced by a more efficient continuous processing technology. With the exception of some large poultry rendering operations, most of the rendering capacity uses the newer continuous rendering process. Prior to the mid 1970's, petroleum based solvents were used to further separate solids from oils, producing meat and bone meal with a 1-2 percent fat content. The increased price of oil corresponding with a market acceptance of a higher fat content has resulted in a virtual phaseout of solvents in the production process. Variation in product quality is more a function of management expertise than technology used. Because meat and bone meal is a small component of all protein sources, it is priced based on competing products such as soybean meal.
Two-thirds of the 45 rendering plants in the United Kingdom use the older batch process but account for only one-fourth of total output. The remaining 75 percent is produced at 15 plants. One firm operates 5 plants and accounts for 50 percent of the total output. Continuous processing technology was introduced in the 1970's and the usage of solvents declined to about 10 percent of total output by the early 1980's (Figure 24). The adoption of newer production technologies and the change in solvent usage appears to lag the United States by at least 5 years.
Key Factors
There are two important structural distinctions between the two countries (Figure 25). A "knacker" industry primarily handles the pick-up of dying and fallen stock from which a product called "greaves" is made. Greaves is either sold as pet food or purchased by renders to be combined with other animal raw materials for processing. The second important distinction is the movement of raw materials (before processing) and/or greaves among different renders. This is attributed in part to the geographic proximity of the plants, relative production efficiencies, and end product requirements. For example, the pet food industry sources specific types of organs and tissues from only certain species.
Figure 26 compares animal protein production for the two countries. The calculations are based on slaughter numbers, fallen stock estimates, and product yield coefficients. This approach is used due to variation of up to 80 percent from different reported sources. At 3.6 million tons, the United States produces 8 times more animal rendered product than the United Kingdom.
The risk of introducing the BSE agent through sheep meat and bone meal is more acute in both relative and absolute terms in the United Kingdom (Figures 27 and 28). Note that sheep meat and bone meal accounts for 14 percent, or 61 thousand tons, in the United Kingdom versus 0.6 percent or 22 thousand tons in the United States. For sheep greater than 1 year, this is less than one-tenth of one percent of the United States supply.
The potential risk of amplification of the BSE agent through cattle meat and bone meal is much greater in the United States where it accounts for 59 percent of total product or almost 5 times more than the total amount of rendered product in the United Kingdom.
Qualitative Analysis of BSE Risk Factors - 15 _________________________________________________________________
Rendering Industry
An estimate of the distribution of rendered product by species is shown in Figure 29. Prior to the United Kingdom's ban on feeding ruminant products to rnminants, 10-20 percent of rendered products went to cattle. The United Kingdom has been a net exporter of animal protein shipping up to 5 percent of total supply.
In the United Kingdom there is much concern for a specific continuous rendering technology which uses lower temperatures and accounts for 25 percent of total output. This technology was originally designed and imported from the United States. However, the specific application in the production process is _believed_ to be different in the two countries.
The application of solvent in the production process requires an additional reheating of product in order to burn off any remaining solvent residues. Whether it is the application of solvent or the reheating of product that may reduce any potential infectivity is uncertain. If all mature sheep meat and bone meal were fed to dairy cows it would amount to 3.4 pounds per cow per year in the United Kingdom and 2.8 ounces per cow in the United States.
Change in U.K. Rendering Processes 1964-1988
· MBM Produced Solvent Extraction
· MBM from Continous Rendering
Figure 24 [[[Not Available...TSS]]]
USDA:APHIS:VS Source: MAFF, United Kingdom
Figure 25
U.S. Rendering Industry Structure Slaughter--->Render<---Fallen Stock
U.K. Rendering Industry Structure Slaughter--->Render<---Knacker(Greaves)<---Fallen Stock
Render
USDA:APHIS:VS
Qualitative Analysis of BSE Risk Factors - 16
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Rendering Industry
Figure 26
Animal Protein Rendered Production - 1989 (less blood, feather, and fish meal)
U.S. U.K.
Total Rendered Product (thousand tons) 3,648 438
Portion from Cattle Slaughter (%) 59
Portion from Hog Slaughter (%) 20
Portion from Poultry Slaughter (%) 21 18 Portion from All Sheep Slaughter (%) 0.6 14
USDA:APHIS:VS
U.S. Rendered Animal Protein* Estimated Species Composition - 1989
Figure 27 [[[Not Available...TSS]]]
Sources: U.S. Dept. of Agriculture U.S. Dept. of Commerce USDA:APHIS:VS National Rendering Assoc.
Qualitative Analysis of BSE Risk Factors - 17
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Rendering Industry
U.K. Rendered Animal Protein* Estimated Species Composition - 1989
Figure 28 [[[Not Available...TSS]]]
Distribution Estimate of Animal Rendered Proteins (percent) - 1989
Figure 29
U.S. U.K.
Pet Food 34 10 Poultry 34 45 Hogs 17 40 All Cattle 13 0* Miscellaneous 2 5
*Prior to BSE restrictions of July 1988, the portion going to cattle was 10-20 percent.
USDA:APHIS:VS
Qualitative Analysts of BSE Risk Factors - 18
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Feed Industry
Because of the relative abundance of protein sources, the usage of concentrates in the United States continues to increase over roughage and pasture (Figure 30). The bulk of concentrates fed are feed grains with very little food grains used (Figure 31). Almost all animal proteins fed to livestock and poultry start as a component of primary concentrate mixes (Figure 32). These feeds often form the basis for additional concentrate feeds. Meat and bone meal accounts for about 3 percent of primary concentrate tonnage (Figure 33) and 1.5 percent of the reported 183 million tons of concentrates fed in 1988 (Figure 34). The United Kingdom livestock production system is largely grass and roughage oriented. Figure 35 contrasts concentrate production with animal inventories. Of the almost 11 million tons of raw materials used in concentrates for 1988, over 5 million tons were from food grains such as wheat and barley. The United Kingdom imports 500-600,000 tons of soybeans per year.
Key Factors
Whereas 75 percent of cattle slaughter and 65 percent of sheep slaughter pass through feedlots in the United States, sheep and cattle in the United Kingdom receive much less concentrates. For dairy, the United States averages 41 pounds of concentrate fed per 100 pounds of milk produced. For the United Kingdom, the average is 21 pounds. Herd size and the number of farms is more skewed in the United States with average concentrates fed per cow varying as much as 3 tons across some States.
Feed formulation in both countries are driven by least cost considerations subject to nutrient requirements. In terms of usage, Figure 36 shows that animal proteins as a percent of major protein substitutes have been 6-7 percent higher in the United Kingdom. It appears that palatability considerations have tempered additional usage of meat and bone meal in the United Kingdom. In the United States, the price for meat and bone meal tracks closely with soybean meal with the latter about $50-60 per ton less. In the United Kingdom, the price of meat and bone meal over the past 3 years has declined. The current price of $210 per ton is now less than the United States price of $220. An important difference in the two countries' feeding practices has been the inclusion (prior to the animal protein ruminant feed ban) of meat and bone meal in calf starter and other calf feeds in the United Kingdom. Calves were typically fed 55-65 pounds of calf starter potentially containing up to 4 percent meat and bone meal and/or blood meal. This amounted to roughly 2.3 pounds of meat and bone meal over a 12 week period. The feeding of meat and bone meal in calf starter in the United States is not _believed_ to occur.
A worst case scenario denoting the highest potential risk would be to add all meat and bone meal produced from mature sheep offal to dairy concentrate feeds. The ratio of dairy concentrate fed to mature sheep meat and bone meal produced forms a measure of relative risk between the two countries. The higher the ratio the greater the dilution of total feed to sheep meat and bone meal produced and the less the risk. For the United States, the ratio is 34,760:1 or over 17 tons of dairy concentrate are fed to each 1 pound of sheep meat and bone meal produced. For the United Kingdom the ratio is 778:1, a difference of 45.
Qualitative Analysis of BSE Risk Factors - 19 __________________________________________________________________________
Feed Industry
Feed Consumed by U.S. Livestock & Poultry (1974 - 1987) (Corn Feed Value Equivalent)
Concentrates ~ Harvested roughage ~ Pasture
Million Tons
Figure 30 [[[Not Available...TSS]]]
Source: USDA:ERS *Preliminary
USDA:APHIS:VS
Feed Concentrates Fed to U.S. Livestock & Poultry (1974 - 1988)
Feed Grains ~ Food Grains ~ Byproducts-
Figure 31 Million Tons [[[Not Available...TSS]]]
*Oilseed meals, animal protein feeds, milr byproducts, and mineral supplements USDA:APHIS:VS Source: USDA:ERS
U.S. Feed Ingredient Mix In Primary Manufacturing- 1984 Total: 95,112,294 Tons
Figure 32 [[[Not Available...TSS]]]
Feed Grains 49% Animal Proteins 6% Microingredients 1% Other 6% Grain Byproducts 13% Minerals 5% Oilseed Meal 20%
USDA:APHIS:VS Source: USDA:ERS
Qualitative Analysis of BSE Risk Factors - 20
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Feed Industry
U.S. Animal Protein Mix In Primary Manufacturing- 1984 Total: 5,413,098 Tons
Figure 33 [[[Not Available...TSS]]]
Meat/Bone Meal 55% Meal & Tankage 9% Feather Meal 5% Dry Milk Prod. 3% Poultry Byprod. 13%
USDA:APHIS:VS Source: USDA:ERS
Feed Concentrates Fed to U.S. Livestock & Poultry - 1988
Figure 34 [[[Not Available...TSS]]]
USDA:APHIS:VS Source: USDA
Qualitative Analysis of BSE Risk Factors - 21
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Feed Industry
U.K. Production of Feed Concentrates and Animal Inventories - 1988
Figure 35
Concentrates Animal Inventories (thousand tons) (thousand head)
All Cattle-All Feed 4,038.8 11,872
Dairy Cows-Dairy Feed 2,706.0 2,911
All Sheep-All feed 413.8 40,942
USDA=APHIS:VS Source: MAFF, United Kingdom
Animal Proteins as a Oilseed Cake & Meal* Percent of Major Feed Components
Figure 36 [[[Not Available...TSS]]]
USDA:APHIS:VS
Qualitative Analysis of BSE Risk Factors - 22
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Qualitative Assessment
Considering the comparative factors presented, with the exception of some similarities in rendering practices, epidemiologic factors believed conducive to the introduction of BSE in the United Kingdom are significantly different in the United States. This is supported by the following points:
Similar changes in the rendering practices have occurred in both countries. Continuous rendering accounts for the vast majority of all product produced. From 1977 to 1982, the portion of United Kingdom product rendered using hydrocarbon solvents dropped from 70 per-cent to 10 percent. Within the United States the decline was at least 5 years earlier with very little if any solvent in current use.
With respect to sourcing of sheep offal, two important differences remain. First, the "knacker" industry in the United Kingdom benefits from a smaller geographic land base and higher density of all animals. In the United States, 80 percent of the sheep are located in the 17 western States, much of which is sparsely populated with limited agricultural alternatives. Across these large rangeland operations, coyotes provide some of the same fallen stock removal services as knackers. Second, the United States rendering industry does not move the amount of raw material between plants as is reported in the United Kingdom.
Compared to the United States, the United Kingdom has 4 times as many sheep and 3 times as many mature sheep on a land mass slightly smaller than the State of Oregon. While scrapie continues in the United States, the number of sheep and farms has trended down. In the United Kingdom, little has been done to control scrapie which has been endemic for several hundred years. Several factors have allowed for an increase in the number of scrapie flocks in the last 10 years. This includes an increase of roughly 1.2 million head per year over the last decade, substantial movement of sheep from the highlands to lowlands and the fluid market for the purchase and sale of animals across the country. Note that in the United Kingdom, 55 percent of the sheep are on 47 percent of the farms. This compares with 51 per-cent of the sheep on 2 percent of the farms in the United States.
In the United Kingdom, sheep make up 28 percent of ruminant meat production versus 1.5 percent in the United States. Mature sheep account for about 10 percent of sheep slaughter in the United Kingdom versus about 6 percent in the United States. Sheep in the United Kingdom account for about 14 percent of all rendered product versus 0.6 percent in the United States. If rendered mature sheep product went directly to dairy cows, it would amount to 3.4 pounds per head in the United Kingdom versus 2.8 ounces per head in the United States.
Even though the United States cattle industry is over 8 times greater, the ratio of all sheep to all cattle is 32 times greater in the United Kingdom. Likewise the ratio of all sheep greater than 1 year to all milk cows is 10 times larger in the United Kingdom. The proximity of the two species in the United Kingdom has changed as incentives and milk quotas have led to an increased number of sheep coming in contact with dairy animals. A factor of consideration is the proportion of rendered sheep material available in proximity to the dairy population. Seventy-two percent of England and Wales' sheep operations contain 81 percent of the sheep and 50 percent of the beef and dairy. In the United States, 58 percent of the sheep operations contain 59 percent of the sheep but only 4.5 percent of the cattle.
Qualitative Analysis of BSE Risk Factors - 23
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Qualitative Assessment
About 98 percent of the BSE cases have been in dairy herds. Herd size distribution is more skewed in the United States with 24 percent of the cows on 2 percent of the herds of 200 plus head. This size class has the highest case rate computed as 329 affected herds per 10,000 herds and is consistent with higher concentrate usage associated with larger herd size. Per 100 pounds of milk produced the United States feeds 41 pounds of concentrate versus 21 pounds in the United Kingdom. How-ever, to measure potential risk from sheep meat and bone meal, the ratio of dairy concentrate fed to mature sheep meat and bone meal produced must be considered, where the larger the ratio the greater the dilution and the less the potential risk. For the United States, the ratio is 34,760:1 or over 17 tons of dairy concentrate fed to each pound of sheep meat and bone meal produced. For the United Kingdom the ratio is 778:1.
Because of the purported long incubation period of the BSE agent, the average age of dairy cows becomes critical. In the United States, the average age is 3.8 years or 53 percent of all dairy cows are less than 4 years of age. In the United Kingdom, the average age is 5.1 years with 70 percent of dairy cows greater than 4 years. Note that 89 percent of the reported BSE cases are cows 4 years of age or older.
The usage and composition of concentrates varies greatly across the two countries. The United States feeds far more concentrates and has an abundance of plant based proteins such as soybean meal and cotton-seed meal. The United Kingdom has traditionally exported up to 5 percent of meat and bone meal produced and imported 500-600,000 tons of soybeans. Moreover, the portion of animal proteins used as a percent of all other major feed proteins has been 6-7 percent less in the United States than United Kingdom. Also critical has been the in-clusion of meat and bone meal as a protein source in United Kingdom calf starter feeds. Comparable feeds in the United States are believed to contain plant based proteins.
While this qualitative analysis suggests that the potential risk of BSE at the aggregate level is substantially less in the United States than the United Kingdom, recognition of potential variation in the levels of risk factors across geographic areas does not occur. Of further consideration are factors such as the concentration of mature sheep slaughter, rendered products produced, and the proximity of rendered products from mature sheep offal to dairy populations. Also, comparative usage of specific technologies in the rendering industry and verification of the usage of animal proteins in calf starter feeds. A more indepth quantitative analysis of these and other factors are contained in the APHIS-VS Ouantitative Risk Assessment of BSE in the United States...
Qualitative Analysis of BSE Risk Factors - 25
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List of Figures
U.S. Sheep Inventory 1974-1990 4 Number of Sheep and Lambs by State - 1990 4 U.S. Sheep - County Pop. Distribution - 1987 5 U.K. Sheep Inventory 1978-1989 5 U.K. & U.S. Comparison of Sheep Numbers and Farms by Herd Size - Cumulative Incidence of Scrapie in Sheep 1980-1990 6 U.S. Breed Distribution of Sheep Scrapie Reported (1947-1990) 6 Effect of Indemnity on U.S. Scrapie Reporting 7 Sheep & Lamb Inventories - 1989 7 Total U.S. Cattle Inventory 1974-1990 9 U.K. Beef & Dairy Cattle Inventory 1978-1989 9 Cattle & Calf Inventories 10
Number of U.S. Milk Cows and Average per Cow Milk Production 1965-1989) ......................................10 Total U.S. Milk Production 1965-1989........10 Dairy Cow Inventories, Average Milk Production and Concentrate Fed.11 Comparison of Herds, Cows and U.K. BSE Cases by Herd Size - 1988...11 Sheep and Cattle Operations...11 U.K. Distribution of BSE Confirmed & Suspect Cases by Breed & Functional type...12 Age Distribution of Dairy Cows U.K. Occurrence of BSE - 1989...12 Animal Populations...12 U.S. & U.K. Sheep & Cattle Slaughter - 1989...13 Number and Age of Sheep Slaughter - 1989...14 1989 Geographic Distribution of Plants Accounting for 80 Percent of Sheep & Lamb Slaughter...14 Figure 24 - Change in U.K. Rendering Processes 1964-1988...16 Figure 25 - U.S. & U.K. Rendering Industry Structure...16 Figure 26 - Animal Protein Rendered Production - 1989...17 Figure 27 - U.S. Rendered Animal Protein Estimated Species Composition - 1989...17 Figure 28 - U.K. Rendered Animal Protein Estimated Species Composition - 1989...18 Figure 29 - Distribution Estimate of Animal Rendered Proteins (percent) - 1989...18 Figure 30 - Feed Consumed by U.S. Livestock & Poultry (1974 - 1987)... 20 Figure 31 - Feed Concentrates Fed to U.S. Livestock & Poultry (1974-1988)...20 Figure 32 - U.S. Feed Ingredient Mix in Primary Manufacturing - 1984... 20 Figure 33 - U.S. Animal Protein Mix in Primary Manufacturing - 1984... 21 Figure 34 - Feed Concentrates Fed to U.S. Livestock & Poultry - 1988... 21 Figure 35 - U.K. Production of Feed Concentrates and Animal Inventories - 1988...22 Figure 36 - Animal Proteins as a Percent of Major Oilseed Cake & Meal Feed Components...22
Qualitative Analysis of BSE Risk Factors - 25
==========
From: Terry S. Singeltary Sr.
Subject: Quantitative Risk Assessment of BSE in the United States
Date: February 13, 2000 at 3:43 pm PST
Contents
Executive Summary.....1 Introduction.....2 Systems Model of BSE Epidemiology.....3 Scrapie/BSE Contamination of Rendered Product.....5 Infectious Rendered Product Incorporated into Cattle Feeds.....7 General Parameters and Assumptions of the Systems Model.....7 State-Level Quantitative Risk Assessment.....8 County-Level Quantitative Risk Assessment.....10 Conclusions.....14 List of Figures.....15
_________________________________________________________
Executive Summary
Bovine Spongiform Encephalopathy (BSE) is a major new cattle disease problem. The current hypothesis suggests that BSE is the clinical manifestation of the sheep scrapie agent in cattle. While the disease has not been definitively diagnosed in the United States, sheep scrapie does exist along with the feeding of rendered sheep products to cattle.
A qualitative analysis comparing risk factors of the United States and United Kinkdom provided little evidence to support a broad risk of BSE at the national level. However, the focus was on the aggregate level and did not address regional differences in the livestock production and related slaughter, rendering, and feed industry practices.
This quantitative risk assessment was developed around a systems model of BSE. The model incorporated regional differences in sheep and cattle demographics, scrapie disease status, rendering, and feed industry practices. To identify levels of risk, a worst case scenario was defined by assuming that all meat and bone meal produced from mature sheep offal is mixed in dairy concentrate feeds. Relative risk was measured as the ratio of dairy concentrate fed to mature sheep meat and bone meal produced. The higher the ratio, the lower the potential risk. At the national level this ratio was 34,760 or over 17 tons of concentrate fed to dairy cattle for each 1 pound of sheep meat and bone meal produced. At the State-level the ratios varied from 1,252 to 54 million. At the county-level, the range was from 22 to over 10 million.
The inclusion of meat and bone meal into least-cost feed formulation is dependent on price and palatability. Seven of the top 10 States with the lowest ratio of dairy concentrate fed to sheep meat and bone meal produced (highest risk) can produce more meat and bone than is actually used in feed. Such net surplus States may likely have lower prices and higher rates of inclusion when compared to States which must import. Overall, States with relatively few dairy cows but substantial mature sheep rendered, may be at higher risk than States with large dairy populations.
To address regional differences, rendering trade areas were defined as the county and contiguous counties in which each rendering plant was located. The assumption was that mature sheep meat and bone meal rendered was fed to dairy in each defined area. This approach captured 50 percent of all United States dairy cows but biased upward the potential level of risk. Areas where the ratio of dairy concentrate fed to sheep meat and bone meal produced was less than 100 were considered at highest risk. Only 0.06 percent of all dairy cows were in counties with ratios below 100 and 0.8 percent were in counties with ratios below 1,000. On a regional basis, the largest number of cows in the high risk areas were located in the Upper Midwest.
To incorporate scrapie in the risk assessment, six risk categories were identified based on the reported presence of scrapie by county and the number of dairy cows with Iow ratios of dairy concentrate fed to sheep meat and bone meal produced. Six States had at least one county with documented scrapie along with dairy cows located in a rendering area with a ratio less than 1,000.
Despite wide geographic variation in concentrates fed and sheep meat and bone meal produced, little evidence existed to support a broad risk of BSE among a large portion of the dairy population. This was evidenced by the relative small amount of mature sheep meat and bone meal produced. In interpreting these results, consideration should be given to the simplifying assumptions surrounding the rendering trade areas and feed formulation. Also, this analysis assumes that infected sheep were the sole source of the BSE agent.
1 Qualitative Analysis of BSE Risk Factors in the United States, USDA:APHIS:VS, January, 1991.
Quantitative Risk Assessment of BSE - 1 ________________________________________________________
Introduction
Bovine Spongiform Encephalopathy (BSE) represents a major new cattle disease problem. The disease has been diagnosed in the United Kingdom, Ireland, Oman, and Switzerland. The current leading etiologic hypothesis suggests that BSE is a cattle variant of the sheep scrapie agent. Exposure of cattle to scrapie originated through the feeding of infectious rendered product from scrapie-infected sheep. Although the disease has not been definitively diagnosed in the United States, sheep scrapie exists as does the feeding of rendered sheep products to cattle.
A comparison of the BSE risk factors between the United States and the United Kingdom facilitated a qualitative analysis of the risk of BSE within the United States 1. Similarities exist in rendering processes in the two countries, however, major differences are evident in the sheep and cattle demographics, relative slaughter of sheep and cattle, rendering industry, feeding practices, and composition of feed concentrates. The qualitative analysis of these risk factors suggests little evidence for a broad risk for BSE within the United States as a nation. Nevertheless, regional and temporal differences in the livestock, slaughter, rendering, and feed industries suggest that the risk is not homogeneous throughout the United States.
This quantitative risk assessment develops a systems model of the epidemiology of BSE. Regional differences in the current United States sheep and cattle demographics, scrapie disease status, rendering practices, and feed industry are incorporated into the model in order to identify specific regions of the country in which BSE has the highest risk of occurrence.
1 Qualitative Analysis of BSE Risk Factors in the United States. USDA:APHIS:VS, January, 1991.
Quantitative Risk Assessment of BSE - 2 ________________________________________________________
Systems Model of BSE Epidemiology
The leading hypothesis for the transmission of BSE can be diagrammed with a systems model (Figure 1). Cattle are exposed to the scrapie/BSE agent orally through contaminated animal protein feedstuffs. The feedstuffs become contaminated with infectious material by importation of contaminated protein concentrates from BSE affected countries or by incorporation of domestically- produced contaminated protein concentrates. Contamination of the rendered products occurs when scrapie-infected sheep or BSE-infected cattle or the offal from infected animals are processed by the rendering industry. The agent survives the rendering process to enter the animal protein concentrates.
The systems model for the United States can be simplified after careful evaluation. Only a small amount of animal protein products enter the United States from known scrapie or BSE affected countries, therefore, this contribution appears to be negligible. Importation of live animals from BSE affected countries has been very limited. Further importation has been cancelled and traceback of animals imported over the past 10 years has not identified any clinically affected animals. Consequently, this potential contribution to the systems model appears to be negligible.
The major contributors to the BSE systems model in the United States appear to be domestic scrapie-infected sheep (Figure 2). Infected sheep enter the animal feed chain through the rendering industry, either as offal generated through commercial slaughter or directly through the rendering of dead, dying, or diseased individuals. Rendered sheep products are incorporated into animal protein concentrates and enter cattle feeds as a protein source. Cattle ingest the infectious rendered product. Although the infectious dose is unknown and the oral route is not very efficient, this appears to be the route of infection. If cattle are being infected, then the agent may be recirculated through the rendering of cattle. Subclinically infected cattle generate offal at slaughter and clinically affected animals proceed directly to rendering. The critical control points in the systems analysis for the United States are:
1)the provision of scrapie infected sheep and BSE infected cattle to the rendering indnstry;
2)the survival of the agent through the rendering process; and
3)the incorporation of infectious material into animal protein products such as meat and bone meal.
The infectivity of the final animal feed depends on both the concentration of the scrapie/BSE agent in the rendered product and the relative amount of infectious rendering animal protein in the feed. The survival of the scrapie/BSE agent in the rendering process is an accepted factor in the quantitative risk assessment. Therefore, regional and temporal influences at the other two critical control points, scrapie/BSE contamination of rendered product and infectious rendered product incorporation into cattle feeds, form the basis for the quantitative risk assessment.
Quantitative Risk Assessment of BSE - 3 __________________________________________________________
Systems Model of BSE Epidemiology
Figure I [[[Not Available...TSS]]]
Systems Model of Hypothesized BSE Epidemiology and Surveillance NAHMS 7/25/90
Figure 2 [[[Not Available...TSS]]
Systems Model of BSE Epidemiology (U.K. Hypothesis)
Quantitative Risk Assessment of BSE - 4 _________________________________________________________
Scrapie/BSE Contamination of Rendered Product
No clinical or subclinical BSE cases have been definitively diagnosed within the United States, so that the feedback or amplification route appears to be of minimal importance relative to the direct route of scrapie infected sheep entering the rendering process.
The cumulative incidence of scrapie in sheep over the last decade provides an initial indication of the likelihood of infected sheep by region (Figure 3). The ratio of documented scrapie-infected flocks over the past 10 years compared to the current ewe population is significantly higher for the States east of the Mississippi River compared to the western States. Sixty-nine percent (69%) of the eastern States had a ratio greater than 0.24 infected scrapie flocks per 10,000 ewes compared to 27 percent of the western States. No scrapie infected sheep have been reported in 13 of the contiguous 48 States over the past 10 years.
Scrapie is a disease of mature sheep ( > 1 year of age). Review of United States scrapie program records and the Veterinary Medical Database reveal less than 7 percent of the scrapie diagnoses in ewes less than 24 months of age (Figure 4). Therefore, offal from mature sheep slaughter and pickup of dead, diseased, and downer mature animals constitute the major source of scrapie contamination of rendered product.
Quantitative Risk Assessment of BSE - 5 ________________________________________________________
Scraple/BSE Contamination of Rendered Product
Cumulative Incidence of Scrapie in Sheep 1980-1990
Infected Scropie Flocks/10.000 Ewes
Figure 3 [[[Not Available...TSS]]]
Age Distribution of Sheep Diagnosed with Scrapie - U.S.
Figure 4
Age Number Percent (%)
< 17 Months 0 0
17 to 24 Months 48 6.9
25 to 36 Months 239 34.3
37 to 48 Months 254 36.4
49 to 60 Months 89 12.8
61 to 72 Months 43 6.2
72 Months 24 3.4
USDA:APHIS:VS Source: USDA:APHIS:VS
Quantitative Risk Assessment of BSE - 6 _________________________________________________________
Infectious Rendered Product Incorporated into Cattle Feeds
Rendered animal-derived protein products are incorporated into cattle feeds as a protein source. Concentrations of scrapie are highest in brain and lymphatic tissues and extremely low or absent in blood and muscle so that meat and bone meal appears to be the rendered product of highest risk for incorporation into cattle feeds. The rendering industry in the United States appears to be very localized, with hauling of raw materials within a 100-150 mile radius. As with other basic commodities, transportation of meat and bone meal is an important cost factor. The value of the meat and bone meal is tied to the price of feedgrain protein concentrates such as soybean meal. Incorporation of meat and bone meal into cattle concentrates depends on relative prices of other commodities as factored into least-cost ration formulations.
Although most United States cattle receive concentrates, the most intensive concentrate feeding occurs with feedlot and dairy cattle. Feedlot cattle receive concentrates during the growth and finishing periods, while dairy cattle receive the highest levels of concentrate during peak milk production. Meat and bone meal does not _appear_ to be incorporated into calf starter rations. The incubation period of BSE is postulated to be 2.5 to 8 years. Consequently, feedlot cattle which are routinely slaughtered by 14-16 months of age are highly unlikely to demonstrate clinical signs of BSE even if infected.
General Parameters and Assumptions of the Systems Model
The systems model incorporated 7 major assumptions concerning scrapie contamination of the rendering process and the incorporation of infectious materials into cattle feed:
1) only the direct route of contamination of rendered product, i.e., scrapie infected sheep, was considered;
2) only mature sheep were considered as potentially scrapie infected;
3) all offal from mature sheep slaughter was considered to be processed at the nearest renderer;
4) dead, diseased, or downer mature sheep entered renderers in the same or contiguous counties only;
5) all mature sheep meat and bone meal was considered to be infectious;
6) only dairy cattle were considered to be at risk; and
7) all of the mature sheep meat and bone meal produced is fed to dairy cattle in the same county or contiguous counties in which the product was produced.
These assumptions outline the worst case scenario given the current BSE hypothesis. The purpose of building the model with these assumptions is to identify areas of greatest risk for the occurrence of BSE within the United States.
Quantitative Risk Assessment of BSE - 7 _________________________________________________________
State-Level Quantitative Risk Assessment
The state-level quantitative risk assessment estimated the total dairy concentrate fed, the total mature sheep meat and bone meal produced, and computed the ratio of dairy concentrates fed to the mature sheep meat and bone meal produced. The computed ratios ranged from 1,252 to 54,554,117 for the 48 coterminous States (Figure 5). The areas with the lowest ratios represent the highest risk, for example, the lowest number of pounds of dairy concentrate fed per pound of mature sheep meat and bone meal produced.
A second component of the state-level analysis addressed product availability and usage in formula feeds. The incorporation of meat and bone meal into least-cost feed formulation is dependent on price and palatability. The larger the ratio of meat and bone meal produced compared to the meat and bone meal usage in formula feeds, the more likely that the price will be lower and the product will be used up to the level of palatability. If little meat and bone meal is available compared to the usage in formula feed, then the price will be relatively higher and the usage will be less. Figure 6 provides a comparison of the net animal protein usage for selected States. Figure 7 provides both the ratio of dairy concentrate fed to mature sheep meat and bone meal produced and the ratio of animal protein produced to that used in formula feeds. The States with low ratios of dairy concentrate fed to sheep meat and bone meal produced combined with high ratios of animal protein produced to feed usage have the highest risk of BSE occurrence according to the systems model. Consequently some States with relatively few dairy cattle but a lot of mature sheep rendering, such as Colorado, appear to be at higher risk than some States with large dairy populations such as Iowa.
Ratio of Dairy Concentrates Fed to Sheep Meat & Bone Meal Produced 1989
Figure 5 [[[Not Available...TSS]]]
Quantitative Risk Assessment of BSE - 8 _________________________________________________________
State-Level Quantitative Risk Assessment
Figure 6 [[[Not Available...TSS]]]
USAD:APHIS:VS
Animal Protein Produced and Formula Feed Usage
Selected States - 1984
Figure 7
Dairy Concentrate Animal Protein Prod.
State Fed/Sheep MBM /Feed Usage
Michigan 14,639 1.2
Texas 14,439 4.0
Massachusetts 14,106
Kansas 13,032 3.1
Iowa 8,376 .7
Rhode Island 7,820
Colorado 4,620 4.4
Utah 4,058 2.6
New Mexico 1,561 1.1
New Jersey 1,252 3.3
USDA:APHIS:VS
Quantitative Risk Assessment of BSE - 9 _________________________________________________________
County-Level Quantitative Risk Assessment
The county-level analysis provided more detail than the State-level analysis and adjusted for regional differences within States. Renderers' locations were identified and a rendering trade and acquisition area was defined as the county where the renderer was located plus all of the contiguous counties. All mature sheep offal from slaughter and all dead, diseased, and downer mature sheep Were estimated for each rendering area. Total mature sheep meat and bone meal produced, and dairy concentrates consumed per cow were estimated within each rendering area. The model was used to compute the ratio of dairy concentrates fed compared to mature sheep meat and bone meal produced.
The defined rendering areas contained approximately 50 percent of the total United States dairy cow population. Within individual rendering areas, the ratio of concentrate fed compared to mature sheep meat and bone meal produced varied from 22 to greater than 10 million (Figure 8). The highest risk category has the lowest ratios, eg, a ratio of 20 means only 20 pounds of dairy concentrate fed per pound of sheep meat and bone meal produced. Only 0.06 percent of the United States dairy cattle exist in counties with the highest risk (ratios below 100).
Wide variations exist in the number of dairy cattle located in high risk areas of individual States (Figure 9). On a regional basis, the largest number of cows in high risk areas are located in the Upper Midwest (Figure 10).
The next step in the risk assessment was to incorporate the cumulative reported incidence of scrapie over the last decade (1980-1990) into the systems model. The presence of documented scrapie flocks in a specific rendering area was considered to incriminate all mature sheep meat and bone meal as potentially contaminated. The ratios of reported scrapie flocks per 100 flocks and per 10,000 ewes varied widely across the States (Figure 11).
Six risk categories were identified based on the reported presence of scrapie in specific rendering areas and the number of dairy cows in areas with low ratios of dairy concentrates fed to total mature sheep meat and bone meal produced (Figure 12). Six States (Iowa, Indiana, Kentucky, Michigan, New Jersey, and Texas) had at least one county with documented scrapie in a rendering area and dairy cows with ratios less than 999 pounds of dairy concentrate fed to mature sheep meat and bone meal produced (Figure 13).
Ratio of Dairy Concentrate Fed to Sheep MBM (MBM · Meat & Bone Meal from Sheep Slaughter & Dead Sheep)
Figure 8
Concentrate Fed/ Sheep MBM Produced # of cows % of cows
I. 20-99 5,757 .06%
II. 100-999 85,194 .8%
III 1,000-9,999 621,079 6.2%
IV. 10,000-99,999 1,950,981 19.3%
V. 100,000-9,999,999 1,972,392 19.6%
VI. > or = 10,000,000 371,162 3.7%
Cows Not Considered at Risk 5,078,132 50.4%
10,084,697 100.0%
USDA:APHIS:VS
Quantitative Risk Assessment of BSE - 10 _________________________________________________________
County-Level Quantitative Risk Assessment
# U.S. Cows Where the Ratio of Dairy Fed Concentrate to Sheep MBM is < 1,000 Selected States - 1988
Number of Cows (Thousands)
Figure 9 [[[Not Available...TSS]]]
# of U.S. Cows by Region Where the Ratio Fed Concentrate to Sheep MBM < 1,000 Selected States - 1988
Number of Cows (Thousand)
Figure 10 [[[Not Available...TSS]]]
USDA:APHIS:VS
Qantitative Risk Assessment of BSE - 11 _________________________________________________________
County-Level Quantitative Risk Assessment
Cumulative Reported Incidence of Scrapie, 1980-1990 AND Ratio of Dairy Concentrate Fed to Sheep MBM* Produced Selected States
Figure 11
Incidence Per # Cows Where Ratio
State Reported Flocks 100 Flocks 10,000 Ewes 20-99 100-999 MI 44 2.37 7.09 17,567 IN 43 1.55 7.66 746 NJ 7 1.26 9.22 18 1,793 VA 7 0.35 0.71 14 CO 5 0.28 0.16 2,867 K Y 2 0.23 0.83 1,515 TX 10 0.15 0.08 4,153 2,572 KS 3 0.14 0.23 478 19 IA 9 0.11 0.32 22.083 NE 2 0.08 0.16 939 WY 1 0.07 0.02 169 MN 1 0.03 0.07 19,378
USDA:APHIS:VS -Meat and Bone Meal from Sheep > = 1 year.
BSE Risk Categories
Figure 12
Scrapie Scrapie Ratio* Ratio* Reported Reported < 999 < 9,999 Locally State
I. yes - - - yes - - - II. no yes yes - - - III. no yes no > 10% no no > 10% - - - IV. no yes no yes V. no yes - - - - - - no no no < 10% VI. no no no no
*Ratio of Dairy Concentrate Fed to Sheep Meat&Bone; Meal Prod. USDA:APHIS:VS
Quantitative Risk Assessment of BSE - 12 __________________________________________________________
County-Level Quantitative Risk Assessment
State Risk Categorie based on Scrapie Reported and the Ratio of Daily Concentrates Fed to Sheep MBM Produced**
[[[data not available, will not scan properly...TSS]]]
Quantitative Risk Assessment of BSE - 13 _________________________________________________________
Conclusions
The state and county-level quantitative risk assessments substantiate the conclusions of the qualitative comparison of risk factors between the United States and United Kingdom. Little evidence exists to support a broad risk for BSE among a large portion of the dairy population of the United States. This conclusion is supported by the fact that the proportion of animal proteins produced from mature sheep is extremely low. Substantial geographic variation exists in the ratio of dairy concentrates fed to the sheep meat and bone meal produced. Despite this variation, low ratios of dairy concentrates fed to sheep meat and bone meal produced affect very few cows.
These conclusions must be considered cautiously, since the analysis required a number of simplifying assumptions concerning the rendering industry and feed formulation and usage. Seasonal variation exists in the availability of sheep meat and bone meal as well as competing feed substitutes, therefore, feed formulations may vary considerably, compounding the problem of accurately estimated consumption of mature sheep meat and bone meal by dairy cattle. In addition, the entire risk assessment considers scrapie infected sheep as the only source of the BSE agent.
Quantitative Risk Assessment of BSE - 14 ___________________________________________________________
List of Figures
Systems Model of Hypothesized BSE Epidemiology and Surveillance 4
Systems Model of BSE Epidemiology (U.K. Hypothesis) 4
Cumulative Incidence of Scrapie in Sheep 1980-1990 6
Age Distribution of Sheep Diagnosed with Scrapie - U.S 6
Ratio of Dairy Concentrates Fed to Sheep Meat & Bone Meal Produced - 1989 8
Animal Protein Produced & Formula Feed Usage I - Selected States - 1984 9
Animal Protein Produced & Formula Feed Usage II - Selected States - 1984 9
Ratio of Dairy Concentrate Fed to Sheep MBM 10
# U.S. Cows Where the Ratio of Dairy Fed Concentrate to Sheep MBM is < 1,000 - Selected States - 1988 11
# U.S. Cows by Region Where the Ratio Fed Concentrate to Sheep MBM is < 1,000 - Selected States - 1988 11
Cumulative Reported Incidence of Scrapie, 1980-1990 AND Ratio of Dairy Concentrate Fed to Sheep MBM Produced - Selected States 12
BSE Risk Categories 12
State Risk Categories Based on Scrapie Reported and the Ratio of Dairy Concentrates Fed to Sheep MBM Produced 13
Quantitative Risk Assessment of BSE - 15 ___________________________________________________________
USDA:APHIS:VS AHI2.01/91
End…tss
https://archive.org/details/CAT11066073
https://archive.org/stream/CAT11066073/CAT11066073_djvu.txt
https://bseusa.blogspot.com/2008/08/qualitative-analysis-of-bse-risk.html
FRIDAY, MAY 19, 2023
USDA Announces Atypical L-Type Bovine Spongiform Encephalopathy BSE Detection
https://bovineprp.blogspot.com/2023/05/usda-announces-atypical-l-type-bovine.html
https://prpsc.proboards.com/thread/122/announces-atypical-bovine-spongiform-encephalopa
SATURDAY, MAY 20, 2023
Tennessee State Veterinarian Alerts Cattle Owners to Disease Detection Mad Cow atypical L-Type BSE
https://bse-atypical.blogspot.com/2023/05/tennessee-state-veterinarian-alerts.html
https://prpsc.proboards.com/thread/123/tennessee-veterinarian-alerts-cattle-confirmed
2 weeks before the announcement of this recent mad cow case in the USA, i submitted this to the APHIS et al;
***> APPRX. 2 weeks before the recent mad cow case was confirmed in the USA, in Tennessee, atypical L-Type BSE, I submitted this to the APHIS et al;
Document APHIS-2023-0027-0001 BSE Singeltary Comment Submission May 2, 2023
''said 'burden' cost, will be a heavy burden to bear, if we fail with Bovine Spongiform Encephalopathy BSE TSE Prion disease, that is why this information collection is so critical''...
https://www.regulations.gov/comment/APHIS-2023-0027-0002
https://downloads.regulations.gov/APHIS-2023-0027-0002/attachment_1.pdf
Specified Risk Materials DOCKET NUMBER Docket No. FSIS-2022-0027 Singeltary Submission Attachment
https://www.regulations.gov/comment/FSIS-2022-0027-0002
https://downloads.regulations.gov/FSIS-2022-0027-0002/attachment_1.pdf
Control of Chronic Wasting Disease OMB Control Number: 0579-0189APHIS-2021-0004 Singeltary Submission
https://www.regulations.gov/comment/APHIS-2021-0004-0002
https://downloads.regulations.gov/APHIS-2021-0004-0002/attachment_1.pdf
Docket No. APHIS-2018-0011 Chronic Wasting Disease Herd Certification
https://www.regulations.gov/document/APHIS-2018-0011-0003
https://downloads.regulations.gov/APHIS-2018-0011-0003/attachment_1.pdf
Docket No. FDA-2003-D-0432 (formerly 03D-0186) Use of Material from Deer and Elk in Animal Feed
PUBLIC SUBMISSION
Comment from Terry Singeltary Sr.
Posted by the Food and Drug Administration on May 17, 2016 Comment
Docket No. FDA-2003-D-0432 (formerly 03D-0186) Use of Material from Deer and Elk in Animal Feed Singeltary Submission
https://www.regulations.gov/comment/FDA-2003-D-0432-0011
https://www.regulations.gov/docket/FDA-2003-D-0432
Cwd, cattle, pigs, sheep, raccoons, oh my
Price of TSE Prion Poker goes up substantially, all you cattle ranchers and such, better pay close attention here...terry
"Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material."
Transmission of the chronic wasting disease agent from elk to cattle after oronasal exposure
Justin Greenlee, Jifeng Bian, Zoe Lambert, Alexis Frese, and Eric Cassmann Virus and Prion Research Unit, National Animal Disease Center, USDA-ARS, Ames, IA, USA
Aims: The purpose of this study was to determine the susceptibility of cattle to chronic wasting disease agent from elk.
Materials and Methods: Initial studies were conducted in bovinized mice using inoculum derived from elk with various genotypes at codon 132 (MM, LM, LL). Based upon attack rates, inoculum (10% w/v brain homogenate) from an LM132 elk was selected for transmission studies in cattle. At approximately 2 weeks of age, one wild type steer (EE211) and one steer with the E211K polymorphism (EK211) were fed 1 mL of brain homogenate in a quart of milk replacer while another 1 mL was instilled intranasally. The cattle were examined daily for clinical signs for the duration of the experiment. One steer is still under observation at 71 months post-inoculation (mpi).
Results: Inoculum derived from MM132 elk resulted in similar attack rates and incubation periods in mice expressing wild type or K211 bovine PRNP, 35% at 531 days post inoculation (dpi) and 27% at 448 dpi, respectively. Inoculum from LM132 elk had a slightly higher attack rates in mice: 45% (693 dpi) in wild type cattle PRNP and 33% (468) in K211 mice. Inoculum from LL132 elk resulted in the highest attack rate in wild type bovinized mice (53% at 625 dpi), but no K211 mice were affected at >700 days. At approximately 70 mpi, the EK211 genotype steer developed clinical signs suggestive of prion disease, depression, low head carriage, hypersalivation, and ataxia, and was necropsied. Enzyme immunoassay (IDEXX) was positive in brainstem (OD=4.00, but non-detect in retropharyngeal lymph nodes and palatine tonsil. Immunoreactivity was largely limited to the brainstem, midbrain, and cervical spinal cord with a pattern that was primarily glia-associated.
Conclusions: Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material.
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
Prion Conference 2023
Transmission of the chronic wasting disease agent from elk to cattle after oronasal exposure
Conclusions: Cattle with the E211K polymorphism are susceptible to the CWD agent after oronasal exposure of 0.2 g of infectious material.
Strain characterization of chronic wasting disease in bovine-PrP transgenic mice
Conclusions: Altogether, these results exhibit the diversity of CWD strains present in the panel of CWD isolates and the ability of at least some CWD isolates to infect bovine species. Cattle being one of the most important farming species, this ability represents a potential threat to both animal and human health, and consequently deserves further study.
https://prion2023.org/wp-content/uploads/2023/10/Meeting-book-final-version2.pdf
Volume 31, Number 1—January 2025
Detection of Prions in Wild Pigs (Sus scrofa) from Areas with Reported Chronic Wasting Disease Cases, United States
Abstract
Using a prion amplification assay, we identified prions in tissues from wild pigs (Sus scrofa) living in areas of the United States with variable chronic wasting disease (CWD) epidemiology. Our findings indicate that scavenging swine could play a role in disseminating CWD and could therefore influence its epidemiology, geographic distribution, and interspecies spread.
Conclusions
In summary, results from this study showed that wild pigs are exposed to cervid prions, although the pigs seem to display some resistance to infection via natural exposure. Future studies should address the susceptibility of this invasive animal species to the multiple prion strains circulating in the environment. Nonetheless, identification of CWD prions in wild pig tissues indicated the potential for pigs to move prions across the landscape, which may, in turn, influence the epidemiology and geographic spread of CWD.
https://wwwnc.cdc.gov/eid/article/31/1/24-0401_article
Experimental transmission of the chronic wasting disease agent to swine after oral or intracranial inoculation
Running Title: The chronic wasting disease agent transmits to swine
Discussion
snip...
In the case of feral pigs, exposure to the agent of CWD through scavenging of CWD-affected cervid carcasses or through consumption of prion contaminated plants or soil could allow feral pigs to serve as reservoirs of CWD infectivity. The range and numbers of feral pigs is predicted to continue to increase due to the ability of pigs to adapt to many climates, reproduce year-round, and survive on a varied diet (55 ). The range of CWD-affected cervids also continues to spread, increasing the likelihood of overlap of ranges of feral pigs and CWD -affected environments.
We demonstrate here that PrPSc accumulates in lymphoid tissues from pigs inoculated intracranially or orally with the CWD agent, and can be detected as early as 6 months after inoculation. Clinical disease suggestive of prion disease developed only in a single pig after a long (64 months) incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. However, the low amounts of PrPSc detected in the study pigs combined with the low attack rates in Tg002 mice suggest that there is a relatively strong species barrier to CWD prions in pigs.
https://journals.asm.org/doi/10.1128/jvi.00926-17
Currently, swine rations in the U.S. could contain animal derived components including materials from deer or elk. In addition, feral swine could be exposed to infected carcasses in areas where CWD is present in wildlife populations. The current feed ban in the U.S. is based exclusively on keeping tissues from TSE infected cattle from entering animal feeds. These results indicating the susceptibility of pigs to CWD, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health.
The successful transmission of pig-passaged CWD to Tg40 mice reported here suggests that passage of the CWD agent through pigs results in a change of the transmission characteristics which reduces the transmission barrier of Tg40 mice to the CWD agent. If this biological behavior is recapitulated in the original host species, passage of the CWD agent through pigs could potentially lead to increased pathogenicity of the CWD agent in humans. Interestingly, bioassay of material from the longest surviving >6 month orally challenged pig (72 mpc), which was negative for PrPcwd by all other tests, produced a positive bioassay result. Bioassay of material from additional animals is currently underway. This study demonstrates that pigs can serve as potential hosts for CWD, although with low attack rates and scant PrPcwd accumulation. Detection of infectivity in orally challenged pigs using mouse bioassay raises the possibility that naturally exposed pigs act as a reservoir of CWD infectivity, even though affected pigs do not develop overt clinical signs or readily detectable PrPcwd.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=326166
cwd scrapie pigs oral routes
***> However, at 51 months of incubation or greater, 5 animals were positive by one or more diagnostic methods. Furthermore, positive bioassay results were obtained from all inoculated groups (oral and intracranial; market weight and end of study) suggesting that swine are potential hosts for the agent of scrapie. <***
*** Although the current U.S. feed ban is based on keeping tissues from TSE infected cattle from contaminating animal feed, swine rations in the U.S. could contain animal derived components including materials from scrapie infected sheep and goats. These results indicating the susceptibility of pigs to sheep scrapie, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health. <***
***> Results: PrPSc was not detected by EIA and IHC in any RPLNs. All tonsils and MLNs were negative by IHC, though the MLN from one pig in the oral <6 month group was positive by EIA. PrPSc was detected by QuIC in at least one of the lymphoid tissues examined in 5/6 pigs in the intracranial <6 months group, 6/7 intracranial >6 months group, 5/6 pigs in the oral <6 months group, and 4/6 oral >6 months group. Overall, the MLN was positive in 14/19 (74%) of samples examined, the RPLN in 8/18 (44%), and the tonsil in 10/25 (40%).
***> Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=353091
https://www.ars.usda.gov/research/project/?accnNo=432011&fy=2017
https://www.ars.usda.gov/research/publications/publication/?seqNo115=337105
Conclusions: This study demonstrates that PrPSc accumulates in lymphoid tissues from pigs challenged intracranially or orally with the CWD agent, and can be detected as early as 4 months after challenge. CWD-infected pigs rarely develop clinical disease and if they do, they do so after a long incubation period. This raises the possibility that CWD-infected pigs could shed prions into their environment long before they develop clinical disease. Furthermore, lymphoid tissues from CWD-infected pigs could present a potential source of CWD infectivity in the animal and human food chains.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=337105
Currently, swine rations in the U.S. could contain animal derived components including materials from deer or elk. In addition, feral swine could be exposed to infected carcasses in areas where CWD is present in wildlife populations. The current feed ban in the U.S. is based exclusively on keeping tissues from TSE infected cattle from entering animal feeds. These results indicating the susceptibility of pigs to CWD, coupled with the limitations of the current feed ban, indicates that a revision of the feed ban may be necessary to protect swine production and potentially human health.
https://www.ars.usda.gov/research/publications/publication/?seqNo115=353091
https://www.ars.usda.gov/research/project/?accnNo=432011&fy=2017
https://www.ars.usda.gov/research/publications/publication/?seqNo115=337105
https://www.ars.usda.gov/research/publications/publication/?seqNo115=326166
Component 6: Transmissible Spongiform Encephalopathies
Sheep scrapie agent can infect white-tailed deer after oronasal exposure.
The origin of chronic wasting disease (CWD) is not known, but it has many similarities to the sheep prion disease called scrapie. It has long been hypothesized that CWD arose through transmission of sheep scrapie to deer. ARS researchers in Ames, Iowa, conducted research to determine if scrapie derived from sheep could be transmitted to white-tailed deer. The deer inoculated with sheep scrapie developed clinical signs and the abnormal prion protein could be detected in a wide range of tissues. These results indicate that deer may be susceptible to sheep scrapie if exposed to the disease in natural or agricultural settings. In addition, several strong similarities between CWD in white-tailed deer and the experimental cases of scrapie in white-tailed deer suggests that it would be difficult to distinguish scrapie from CWD in deer or identify scrapie if a case occurs. This information should be considered by deer farmers for keeping their herds free from prion diseases.
https://www.ars.usda.gov/ARSUserFiles/np103/AnnualReports/NP103%20FY2023%20Annual%20Report_Final.pdf
Tuesday, August 12, 2025
Ad hoc Group on the evaluation of bovine spongiform encephalopathy (BSE) risk status of Members Singeltary Review August 2025
https://woahoie.blogspot.com/2025/08/ad-hoc-group-on-evaluation-of-bovine.html
https://prpsc.proboards.com/thread/176/group-evaluation-risk-singeltary-review
FRIDAY, NOVEMBER 14, 2025
The European Union summary report on surveillance for the presence of transmissible spongiform encephalopathies (TSE) in 2024 UK's National CJD Research & Surveillance Unit (NCJDRSU) ceased to function on March 31, 2025
https://efsaopinionbseanimalprotein.blogspot.com/2025/11/the-european-union-summary-report-on.html
FRIDAY, NOVEMBER 21, 2025
While no one was watching: Tenuous status of CDC prion unit, risk of CWD to people worry scientists
https://chronic-wasting-disease.blogspot.com/2025/11/while-no-one-was-watching-tenuous.html
WEDNESDAY, OCTOBER 15, 2025
US NATIONAL PRION DISEASE PATHOLOGY SURVEILLANCE CENTER CJD TSE REPORT 2025
https://prionunitusaupdate.blogspot.com/2025/10/us-national-prion-disease-pathology.html
Terry S. Singeltary Sr.
