Deseret News Archives
Sunday, March 31, 1996
What about using sheep to make animal feed? Britain has banned the practice, but sheep still make up about two-tenths of a percent of the animals ``rendered'' into U.S. feed, said Don Franco of the National Renderers Association. But no more than 50 [sic -- webmaster] cases of scrapie a year are found in the nation's 8.9 million sheep, meaning it's unlikely that U.S. animal feed could be tainted, Detwiler said.
The BSE epidemiology studies have suggested that BSE was linked to the discontinuance of the solvent extraction step in the rendering process in the U.K. However, Dr. Taylor presented data at the joint FDA/USDA meeting in Riverdale, May 13, 1996, showing that none of the three steps in the solvent extraction process reduced TSE infectivity. So where does this leave us?
Well, if not a direct link let's go for an indirect one.
The discontinuance of solvent extraction of greaves* meant that the final renderer extracted less fat from greaves, about 2/3rds. Now, some of these less valuable greaves were coming from "Knacker Yards". An April 6th, 1991 article in 'The Economist' Britain Section discusses knackers. The picture shows of a whole bunch of dead sheep on the ground with a "Knackered Knacker" (man) standing by them.
*Greaves are a U.K word for the solid portion prior to fat extraction, either by solvent or mechanical means. In the U.S. we refer to the solid unground fraction as "crax". Before fat is extracted they are "wet crax", after "dry crax" or just plain "crax".
Some quotes from the article:
"Knackers would then take the carcasses to pieces, sell the meat off as pet food, the tallow off to pharmaceutical companies, the hides as leather and the rest to the renderers to turn into animal feed."If you wanted to find the highest dose of TSE's in the world you would have gone (and still go) to a U.K. Knacker yard. The key here is that Knackers extracted some of the fat, hence they had to at least partially render the material. So you have Knackers buying deadstock from farmers and selling tallow and greaves to..... Highest Bidder?"Knackers are closing down, Of the 130 in Britain, 12 have closed in the past year. Scotland has been particularly badly hit, because the two big companies that ran the industry have both closed."
If this industry did exist in the U.S., which it does not, farmers would have been lined up at the Knackers door with money in hand. Or maybe that's how farmers were paid for their deadstock.
The reasoning behind the exclusion of fats from any ban or *potential* ban is that Dr. Taylor's studies on both scrapie and BSE infectivity in rendered products show that no detectable infectivity occurs in rendered fats even in those systems that produced infective meat and bone meal. Most rendered fats are filtered using a media such as diatomacious earth to remove even trace levels of proteinaceous materials. The resulting filtered fat is a pure chemical triglyceride which contains NO animal tissue which is *potentially* associated with the infective agent.
2.4.5 The traditional method of cooking is used by plants processing about 20% of the raw material. The average particle size of material entering the cookers is 40mm and average cooking time about 3 1/2 hours. Maximum temperatures range from 120-135‘C under atmospheric pressure with a normal maximum of about 125‘C. However one plant cooks under pressure (2 bar) for 35 minutes at 141‘C. In some plants the load is discharged once the maximum temperature is reached, in others there may be a holding time of up to 20 minutes. On discharge the free run fat is drained off and the residual greaves removed for pressing and/or centrifugation to extract more fat. The dried greaves is subsequently ground to produce meat and bonemeal or sold as greaves to other renderers for further processing.
2.4.6 There are four continuous systems employed in the UK. They were first introduced in the early 1970s and now process about 80% of the raw material.
Stord Duke system
The system works on the principle of a deep fat fryer. The rendering vessel operates with a high proportion of liquid fat, the heat being applied via a steam jacket and a steam heated tube rotor. The particle size of raw material entering the cooker is 20-50mm. Maximum temperatures achieved are between 135‘C and 145‘C with an average residence time of at least 30 minutes. The protein material is then pressed before being ground into meat and bonemeal.
Stord Bartz system
There are a number of different types and sizes of Stord Bartz systems. The material (reduced to a particle size of 20-50mm) is heated by a steam heated disc rotor. The discs occupy the length of the rendering vessel. The average maximum temperature achieved is around 125‘C and an average residence time of between 22 and 35 minutes. Pressing and grinding is similar to the procedure operated in the previously described system.
Anderson Carver-Greenfield system
Finely minced (to a size of less than 10mm) raw material is first mixed with recycled heated tallow to form a slurry. This is then pumped through a system of tubular heat exchangers with vapour chambers under partial vacuum before being centrifuged and pressed. The heat treatment involves a maximum process temperature of 125‘C with an average residence time of between 20 and 25 minutes.
Protec De-Watering System
Raw material is initially minced to a particle size of 10 mm before being heated to 95‘C for 3-7 minutes. The liquid phases (fat and water) are removed by centrifuging or light pressing and are further separated to recover the tallow. The resultant solids are dried at temperatures ranging from 120‘C to 130‘C.
At the end of 1987, John Wilesmith, of the Central Veterinary Laboratory looked at the first 200 cases of BSE and did a very careful analysis of the epidemiology. He found the only common feature was that every single case had been fed proprietary concentrates or protein supplements and he identified that the vehicle that carried the infection was the meat and bone meal." "The precipitating factor causing BSE was a sudden cessation of hydrocarbon solvent extraction of tallow in the rendering system. Why did this occur? Well, this process probably inactivated the causal agent sufficiently to prevent disease and when that procedure was stopped independently by the rendering companies for commercial reasons, this permitted sufficient infectivity to pass into the feed and cause disease. It was then recycled and initiated the escalation in the epidemic from mid 1989 onwards.
How had solvent extraction of tallow prevented the disease? We think by the double heat process which this particular kind of rendering utilised and in particular the use of a second wet heat stage using steam in a low fat environment. When did that happen? It happened in the late l 970s and early 1980s especially in the period 1981/82 when cattle were first exposed to sufficient agent to cause disease which was first recognised five years or so later after the incubation period was complete."
There are (or were) two separate industries involved in the production of animal feedstuffs based on meat and bonemeal. They are the rendering industry, milling the meat and bonemeal, and the feed compounding industry. The renderers do not normally sell their product direct to farmers but to the compounders.
The information that follows derives from discussions with a now-retired well-known technologist who worked for one of the major rendering companies during the period in question.
After the first heated stage of rendering, much of the fat (tallow) was removed by pressing, leaving behind the "greaves" containing residual fat. Why was solvent extraction ever involved? It was because it was virtually impossible, in the small-scale batch processing plants that existed up to the early 1960s, to mill the meat and bonemeal without first removing the residual fat, by solvent extraction. Up to the early 1960s, the renderers therefore carried out solvent extraction, and sold the milled product to compounders on a commercial specification of 50% protein, and very low fat content. After extraction the residual solvent then was removed from the product by "stripping" it with steam nominally at 120 deg C plus, (though, delving further into detailed history, I am told by my informant, that it was, in practice, not always operated above 100 deg C). The fat-in-solvent solution was then evaporated to leave the by-product, tallow.
By the early 1960s, there was a worldwide trend to move from a larger number of renderers operating small-scale batch processing to fewer large-scale continuous processing plants of modern design, on which, moreover, it was possible to mill the product containing the residual fat, so that there was no technical need for solvent extraction or for the subsequent steam stripping of solvent residues. These changes were taking place worldwide, not just in the UK.
Meanwhile, tallow was increasingly being added as an ingredient during compounding, as an energy supplement,. Realization dawned that it was ridiculous to go to all the trouble, expense, hazard and environmental pollution involved in removing residual tallow by solvent extraction, only for it to be added back in compounding. This led to the increasing adoption of a commercial specification of a 45% protein meal with 8-10% fat, which could, of course, be achieved, and milled, without solvent extraction. The trend started with the largest renderers back in the early 1960s, not "in the late l 970s and early 1980s especially in the period 1981/82" as the typical rationale has it. Moreover, the major UK renderers doing this were not only doing it in the UK but in their factories in continental Europe (plus of course there was a substantial export trade from the UK).
I have heard that two small renderers in Scotland carried on solvent extracting after everyone else had stopped, but that is hearsay. In any event, research in the last few years on the conditions necessary to inactivate BSE infectivity demonstrates that the steam-stripping process would be most unlikely to have inactivated it.
The economic benefit of removing the two unnecessary processes, is interlinked with the changes in technology that made it possible, in operating scale and in concentration of the industry into fewer larger units. The economics were obviously significant in the 1970s after the oil crisis of 1973 onwards (more from energy usage than from solvent, which was recovered); and the safety aspect even more significant in the UK in view of the general tightening up on industrial safety after the Flixborough disaster in June 1974.
So it would seem that the changes in processing started much earlier than is generally supposed, and were not confined to the UK.
Regarding the background of ultra-low prevalence of sporadic BSE, This seems possible. Some experts still have reservations about sheep meat and bonemeal as the sole source, particularly with regard to how the sheep scrapie prion changed, during passage through cattle, to the BSE prion. Some of those offer the view that BSE has always existed at low and previously unrecognised level in cattle, and the inclusion of cattle meat in the animal feed resulted in an amplification effect. Some older farmers and vets now say, with hindsight, that it has always existed, but occurred so rarely that when a cow had "the staggers" nobody recognised it as anything but an inexplicable one-off event.
It extends to pet foods for domestic cats and dogs "produced in mills which handle material for farm animals or horses." But what about pet foods produced elsewhere? Apparently not covered. "Mammalian origin" appears to cover chicken meat or waste or cattle or chicken manure if incorporated in "meat and bonemeal", but it does not appear that this would prevent a farmer from directly feeding such materials, other than in "meat and bonemeal" form, to his animals.
The ban is (broadly) on feeding mammalian protein to farm animals. Effectively, this means that such protein will have to be destroyed. In the UK at least, almost all petfoods use only food fit for human consumption. All protien derived fron SBOs (specified bovine offals, the infective tissues) will be destroyed anyway. We will be checking cattle rations to ensure that they are free of such protein.There are no restrictions on using chicken protein.
The Regulations exclude from use in meat and bonemeal: products derived from domestic pets (other than budgies or parrots) and pork protein, but _not_ chicken. The rules do not appear to exclude the use of sheep and beef protein in chicken and pig rations or the use of chicken (and broiler litter), domestic pets and pork protein in cattle feed. Cattle and chicken manure have also been employed in animal rations in the past.
603. Inspection of meat and meat food products
(a) Examination of animals before slaughtering; diseased animals slaughtered separately and carcasses examined
For the purpose of preventing the use in commerce of meat and meat food products which are adulterated, the
Secretary shall cause to be made, by inspectors appointed for that purpose, an examination and inspection of all
cattle, sheep, swine, goats, horses, mules, and other equines before they shall be allowed to enter into any
slaughtering, packing, meat-canning, rendering, or similar establishment, in which they are to be slaughtered and
the meat and meat food products thereof are to be used in commerce; and all cattle, sheep, swine, goats, horses,
mules, and other equines found on such inspection to show symptoms of disease shall be set apart and slaughtered
separately from all other cattle, sheep, swine, goats, horses, mules, or other equines, and when so slaughtered the
carcasses of said cattle, sheep, swine, goats, horses, mules, or other equines shall be subject to a careful
examination and inspection, all as provided by the rules and regulations to be prescribed by the Secretary, as
provided for in this subchapter.
(b) Humane methods of slaughter
For the purpose of preventing the inhumane slaughtering of livestock, the Secretary shall cause to be made, by
inspectors appointed for that purpose, an examination and inspection of the method by which cattle, sheep, swine,
goats, horses, mules, and other equines are slaughtered and handled in connection with slaughter in the slaughtering
establishments inspected under this chapter. The Secretary may refuse to provide inspection to a new slaughtering
establishment or may cause inspection to be temporarily suspended at a slaughtering establishment if the Secretary
finds that any cattle, sheep, swine, goats, horses, mules, or other equines have been slaughtered or handled in
connection with slaughter at such establishment by any method not in accordance with the Act of August 27, 1958
(72 Stat. 862; 7 U.S.C. 1901-1906) until the establishment furnishes assurances satisfactory to the Secretary
that all slaughtering and handling in connection with slaughter of livestock shall be in accordance with such a
method.
604. Post mortem examination of carcasses and marking or labeling; destruction of carcasses condemned; reinspection For the purposes hereinbefore set forth the Secretary shall cause to be made by inspectors appointed for that purpose a post mortem examination and inspection of the carcasses and parts thereof of all cattle, sheep, swine, goats, horses, mules, and other equines to be prepared at any slaughtering, meat-canning, salting, packing, rendering, or similar establishment in any State, Territory, or the District of Columbia as articles of commerce which are capable of use as human food; and the carcasses and parts thereof of all such animals found to be not adulterated shall be marked, stamped, tagged, or labeled as ''Inspected and passed''; and said inspectors shall label, mark, stamp, or tag as ''Inspected and condemned'' all carcasses and parts thereof of animals found to be adulterated; and all carcasses and parts thereof thus inspected and condemned shall be destroyed for food purposes by the said establishment in the presence of an inspector, and the Secretary may remove inspectors from any such establishment which fails to so destroy any such condemned carcass or part thereof, and said inspectors, after said first inspection, shall, when they deem it necessary, reinspect said carcasses or parts thereof to determine whether since the first inspection the same have become adulterated, and if any carcass or any part thereof shall, upon examination and inspection subsequent to the first examination and inspection, be found to be adulterated, it shall be destroyed for food purposes by the said establishment in the presence of an inspector, and the Secretary may remove inspectors from any establishment which fails to so destroy any such condemned carcass or part thereof.
605. Examination of carcasses brought into slaughtering or packing establishments, and of meat food products issued from and returned thereto; conditions for entry The foregoing provisions shall apply to all carcasses or parts of carcasses of cattle, sheep, swine, goats, horses, mules, and other equines or the meat or meat products thereof which may be brought into any slaughtering, meat-canning, salting, packing, rendering, or similar establishment, and such examination and inspection shall be had before the said carcasses or parts thereof shall be allowed to enter into any department wherein the same are to be treated and prepared for meat food products; and the foregoing provisions shall also apply to all such products, which, after having been issued from any slaughtering, meat-canning, salting, packing, rendering, or similar establishment, shall be returned to the same or to any similar establishment where such inspection is maintained. The Secretary may limit the entry of carcasses, parts of carcasses, meat and meat food products, and other materials into any establishment at which inspection under this subchapter is maintained, under such conditions as he may prescribe to assure that allowing the entry of such articles into such inspected establishments will be consistent with the purposes of this chapter.
Process changes to reduce waste load include dry cleanup of animal holding pens and collection of blood, paunches, and by-product materials for a render. Two pretreatment systems were considered to further improve effluent quality: a simple settling basin and a dissolved air floatation system. The changes would reduce waste by 80% or 60,000 pounds of BOD per year and water use by 25% or 1,000,000 gallons per year for a savings of $1,500 per year. (1986)
the R&D stage of the hot boning program is almost complete. Initial results indicate a possible compromise between strict microbiological adherence and practical industry considerations; the splitting saw developed by Adept Engineering and installed at E.G. Green's has been demonstrated to industry. a system for mould freezing bulk meat is expected to be operational by March 1995. The key advantages to an integrated system for dicing, mould freezing and transporting manufacturing meat in unitised blocks suitable for container loading
Banning the feeding of ruminants to ruminants has resulted in sharply falling rates of infection in Britain, but new infection has been continuing because of such causes as old feed stocks on farms (in the late 80's), farmers feeding infected chicken rations to cattle, and cross-contamination in feed mills (extremely hard to prevent).
The FDA has announced it's support of the ban, and is initiating regulatory activity toward that result.
However the American Feed Industry Association which represents the *feed* industry does NOT agree with the call for a voluntary ban. Also vocally NOT supported by the Livestock Conservation Instiute who's members include 6 major national Ag associations, 46 producer organizations and 33 publicly supported organizations.
Of course the North American Rendering Industry does not support the call for a voluntary ban.
Reacting to the mad cow disease panic in Britain, the United States livestock industry and veterinary medical groups said Friday that they will immediately establish a voluntary ban on the use of all ruminant parts in animal feed. No case of mad cow disease has been found in this country in 10 years of monitoring. But federal officials said they supported the move from the livestock and veterinary groups as an extra safeguard.
A voluntary ban by sheep renderers in the United States has led to the removal of an estimated 85 percent of sheep parts in animal feed. It is believed the British cattle contracted the animal variety of the disease from eating sheep offal that was mixed with feed.
Nevertheless, the federal Food and Drug Administration announced Friday that it ''will expedite regulations prohibiting all ruminant protein in ruminant feeds.'' Dr. Michael Blackwell, an FDA official, said that his agency and the industry agreed on the need for a broader proposal because of developments in Britain.
The groups supporting the voluntary ban include the National Cattlemen's Beef Association, the American Sheep Industry Association, the National Milk Producers Federation, the American Veterinary Medical Association, the American Association of Bovine Practitioners and the American Association of Veterinary Medical Colleges.
While Britain copes with the devastating effects of mad cow disease, the United States livestock industry is bickering over whether it should continue feeding animal byproducts to cattle, a practice that has been linked to the deadly disease.
On one side of the debate is the feed manufacturing industry, which says meat and bone meal additives are perfectly safe -- at least until scientific evidence proves otherwise. On the other side is a coalition that includes consumer advocates, veterinarians and the country's largest cattle association. They argue that since the additives could be dangerous to human health, they must not be fed to cattle. Scientists believe that the British cattle were infected by eating contaminated meat and bone meal.
``It's been shown that these additives are a risk factor for BSE in Britain,'' said Gary Weber, director of beef safety and cattle health for the National Cattlemen's Beef Association. BSE stands for bovine spongiform encephalopathy, the scientific name for mad cow disease. ``We are going to do absolutely everything to make sure it never happens here,'' Weber said. ``We cannot afford to fix a problem once it has occurred.''
However the American Feed Industry Association, which represents 600 manufacturers and suppliers, contends there is no reason for rash action. Rex Runyon, the association's vice president for public affairs, said concern over mad cow disease is exaggerated and that there is no sound reason for changing bovine feeding practices. ``We feel strongly that any ban should not capitulate to the emotions of an issue,'' Runyon said. ``It's time for cooler heads to prevail and to look at the science.''
The debate is expected to heighten April 22 when the Food and Drug Administration begins writing regulations that would ban the practice, a process that will take at least several months. The government took a preliminary step earlier this month by urging farmers to comply with a voluntary ban on meat and bone meal.
But because there is no proof that the feed supplements are dangerous, farmers aren't rushing to halt their use. ``Some farmers might stop using ruminant protein, and some won't until there is a regulation,'' said Randy Shaver, UW-Madison dairy extension specialist.
Animal renderers produce meat and bone meal by grinding and mixing parts of the cattle that are not fit for human consumption. The product, which is rich in protein, calcium and phosphorous, is fed to dairy cattle, many of which end up as hamburger.
One million farmers raise 103 million beef and dairy cattle in the United States, according to the cattlemen's association. The industry provides $40 billion in direct income to the livestock industry and generates $160 billion for the U.S. economy.
Farmers say the practice of feeding ground cow parts to other cattle is relatively common because it is a cost-effective way to meet the animals' nutritional needs. Plant-based supplements such as roasted soybeans do the trick, but can cost up to 30 percent more than meat and bone eal.
A permanent ban on animal byproducts means farmers would be forced to use alternative and more costly sources of protein. What's more, farmers worry about what would become of their cattle carcasses if there was no longer a market for the rendered parts. ``You can't land-fill this stuff,'' said Jerry Lehman, president of the Wisconsin Cattlemen's Association.
Area feed mill managers say they've been inundated with questions from farmers who feed the additives to cattle wondering whether to continue to do so. ``The dairy farmer in Dane County really wants to do what is right,'' said Dan Neckvatal, marketing manager for Mounds Agri-Service in Middleton, which sells feed additive. ``But based on the information we have, we don't think there is ever going to be a problem,'' he said.
Pete Gross, feed division manager for Cottage Grove Cooperative, said some area dairies have stopped using meat and animal protein supplements in recent weeks. Land O'Lakes is heavily marketing a soybean meal substitute while other farmers are turning to a pork-based additive, Gross said. ``There is reason to be concerned about ruminant meat and bone meal because we don't know enough about it,'' he said. ``There better be some caution out there. We don't want to wreck our market.''
It's clear that even the poultry industry is afraid of that. Tyson Foods, the country's largest chicken producer, has removed meat and bone meal from its birds' diet. ``We basically did it to extricate ourselves from the controversy,'' said Ed Nicholson, a Tyson spokesman in Springdale, Ark. He said that the additive represented less than 1 percent of the birds' diet and there is no indication that there are health concerns regarding poultry. ``It's more a matter of public confidence,'' Nicholson said.
For more information on rendering and feed manufacturing in the United States, obtain a copy of
"United States Rendering and Feed-Manufacturing Industries: Evaluation of Practices with Risk Potential for BSE,"which is published by USDA:APHIS:VS. The publication is free. You can contact USDA:APHIS:VS by telephone, (970)490-7899, internet, NAHMS_info@aphis.usda.gov, fax (970)490-7899, or snailmail:
Centers for Epidemiology and Animal Health (CEAH)
USDA:APHIS:VS
555 South Howes
Attn NAHMS
Fort Collins, CO 808521
You will need the item number to order. It is C3.1192 It only takes a few days to recieve the publications once you order them. Other BSE related publications and item numbers include the following:
BSE: Implications for the US, C002.1295 Quantitative Risk Assessment of BSE in the US, AHI2.0912 Qualitative Analysis of BSE risk factors in the US, AHI1.092I have worked at two veterinary diagnostic labs that take sheep in the past few years, and from my experience, sheep are pretty much treated like nuclear waste. They are necropsied (autopsied) away from other species and there are special containers designated "sheep only" into which all sheep parts go so that they are kept separate from renderable material. Sheep remains are then incinerated as biohazardous waste. All of the pathologists I've worked with have been very careful to follow the correct proceedures and make sure renderable materials do not become contaminated with sheep materials. However, I believe that this is done on a voluntary basis.