Real and perceived issues involving animal proteins - C. R. Hamilton

C. R. Hamilton
Director Research and Nutritional Services
Darling International Incorporated
U.S.A.

THE RENDERING INDUSTRY

The rendering industry has and continues to be closely integrated with animal and meat production in countries where these industries are well established. On a global perspective, rendering provides an important service to society and the animal feeding industries by processing approximately 60 million tonnes per year of animal by-products derived from the meat and animal production industries. During slaughter and processing, between 33 and 43 percent by weight of the live animal is removed and discarded as inedible waste. These materials, which include fat trim, meat, viscera, bone, blood and feathers are collected and processed by the rendering industry to produce high quality fats and proteins that have traditionally been used in the animal feed and oleochemical industries around the world. Without the rendering industry, the accumulation of unprocessed animal byproducts would impede the meat industries and pose a serious potential hazard to animal and human health.

One definition of rendering is to ‘clarify or purify by melting’ (heat processing). Unprocessed animal by-products may contain 60 percent or more water (Figure 1).

The primary reasons for using heat when processing these raw materials are to remove the moisture and facilitate fat separation. Desiccation significantly reduces the total volume from 60 million tonnes of raw material to about 8 million tonnes of animal proteins and 8.2 million tonnes of rendered fats. Stored properly, these finished products are stable for long periods of time. Heat processing also benefits the finished product customer. The temperatures used (115° to 145° C) are more than sufficient to kill bacteria, viruses and many other micro-organisms, to produce an aseptic protein product that is free of potential biohazards and environmental threats. Done correctly, heat processing also denatures the proteins slightly, which enhances their digestibility.

Figure 1. Raw material composition

Modern efficient rendering facilities are concentrated in countries and regions possessing strong and well-established animal production industries. Renderers in North America process nearly 25 million tonnes of animal byproducts per year, while those in the European Union process about 15 million tonnes. Argentina, Australia, Brazil and New Zealand collectively process another 10 million tonnes of animal byproducts per year. The total value of finished rendered products, worldwide is estimated to be between US$6 and US$8 billion per year.

RENDERED PRODUCTS - NUTRITIONAL VALUE

Animal products include meat and bone meal, blood meal, poultry by-product meal (poultry meal) and feather meal. These are all concentrated sources of protein and amino acids and some are also good sources of vitamins and essential minerals (Table 1).

This makes them important feed ingredients for livestock, poultry and companion animals in the United States and many other countries of the world. Meat and bone meal, blood meal, feather meal and poultry meal are suitable for use in feeds for a wide range of animal species, including fish and shrimp (Table 2).

As shown in Figure 2, more than two million tonnes of meat and bone meal and poultry meal combined are used annually by the United States feed industry alone. Animal proteins have traditionally been important sources of proteins and other nutrients for livestock and poultry in the United States and their acceptance in Latin America and Asia has grown substantially in the past five years. Animal proteins are also used extensively in pet foods. About 1.5 million tonnes of meat and bone meal and poultry meal is used by the United States pet food industry each year. The use of non-marine animal proteins in aquaculture feeds is a relatively new practice, but this application is expected to continue to grow, especially as competition and prices for fishmeal increase.

TABLE 1
Nutrient composition of animal proteins^a

^a NRC 1994; ^b Ring or flash dried; ^c Dale, 1997

TABLE 2
Suitability of animal proteins to supply a portion of the protein in feeds for various animal species

^a Guaranteed to be free of ruminant material. ^b As a partial replacement for fishmeal. ^c Approximately 25 to 40% of the dry matter in premium dog foods are animal by-products.

Some nutritionists underestimate the digestibility and the nutritional value of animal proteins. This misperception dates back many years to when poor processing techniques and equipment were used to render animal by-products. Since that time, new processes, improved equipment and greater understanding of the effects of time, temperature and processing methods on amino acid availability have resulted in significant improvements in the digestibility of animal proteins. Improved understanding as to how best to incorporate them into commercial formulas and improved formulation procedures also increased the nutritional value of animal proteins. Data published since 1984 demonstrate that the digestibility of essential amino acids, especially lysine, threonine, tryptophan and methionine, in meat and bone meal, has improved (Table 3).

BIOSECURITY AND FINISHED PRODUCT SAFETY

Biosecurity of food and food related products is largely perception based on trust and education. Food and feed are derived directly or indirectly from biological organisms. Natural variation, the environment, storage conditions, usage and the potential interaction with other biological organisms (such as micro-organisms) make it impractical to guarantee food safety in absolute terms. Despite the best efforts on the part of companies, farmers, regulatory agencies, politicians and others involved in the food chain, all of the potential risks cannot be alleviated 100 percent of the time. Therefore, it is necessary to manage these risks using sound scientific principles and facts. In some recent crisis situations, politics, fear and supposition have replaced logic and science in risk management decisions.

Figure 2. Animal protein usage by the United States' feed industry

TABLE 3
Digestibility of meat and bone meal since 1984

^a Jorgensen et al., 1984; ^b Knabe et al., 1996; ^c Batterham et al., 1990.^d Firman, 1992; ^e Parsons et al., 1997; ^f Pearl, 2001b

During the past decade, a number of safety-related challenges have daunted the rendering industry. These challenges resulted from perceived rather than proven risks. Public and political perceptions were influenced by media sensationalism, a general movement of society away from its agrarian roots, lack of scientific knowledge concerning bovine spongiform encephalopathy (BSE) and other hazards, inadequate analytical procedures for routine detection of potential hazards such as dioxins, public expectations that government and industry assure a safe food supply, opportunistic marketing strategies and the political agendas of activist organizations. The Precautionary Principle adopted by the European Union has served to catalyze these perceptions because in its development and enforcement, perceived risks and political image frequently overruled science.

The World rendering industry recognizes its role in assuring food safety and in protecting human and animal health. The rendering process is an effective method for ensuring biosecurity because processing conditions and volumes, raw material characteristics and drying create an unfavorable environment for viruses, bacteria and other micro-organisms to survive and grow. Rendering is the most logical method for collecting and processing animal by-products because it possesses the infrastructure to safely and responsibly recycle these products, allow traceability and produce safe finished products.

The rendering industry is closely regulated by the appropriate agencies within the resident region, country or province. In the United States, State and Federal agencies each routinely inspect rendering facilities for compliance to applicable regulations and finished product safety tolerances. Rendering facilities are inspected by the United States Food and Drug Administration (FDA) for compliance to BSE related regulations. State Feed Control Officials inspect and test finished products as they enforce quality, adulteration and feed safety policies.

Rendering industry organizations provide technical support and education in quality assurance and feed safety. Using United States based organizations as examples, the Animal Protein Producers Industry (APPI) administers industry-wide programmes for biosecurity, pathogen reduction, continuing education and third-party certification for compliance to BSE related regulations. The Fats and Proteins Research Foundation (FPRF) solicits and funds industry and university research to address pertinent biosecurity and nutrient value issues.

Three primary food safety issues dominate discussions about the safety of feeding animal proteins to animals. These are Salmonella contamination (bacterial pathogens), BSE and dioxins. Each of these issues present legitimate concerns and all are known to threaten animal and human health. However, in each case, the risk of spreading these risks through finished rendered products is largely perceived rather than factual. The value of the rendering process as a mechanism to control risks of microbial pathogens as well as other hazards (with the possible exception of the agent causing BSE) is illustrated in Table 4, which is based on a report from the United Kingdom Department of Health (2001).

Salmonella

Salmonella are destroyed by heat when exposed to temperatures of 55° C for one hour or 60° C for 15 to 20 minutes (Franco, 1993). Processing temperatures of between 115° C and 145° C are used to render animal by-products. These temperatures are more than sufficient to kill Salmonella and other pathogenic bacteria present in raw animal by-products (Tables 4 and 5). However, Salmonella are opportunistic organisms and may re-contaminate products after cooking or processing and during storage, transport and handling. Post process contamination is of concern for all feed ingredients and not restricted only to animal proteins. Despite this fact, animal proteins continue to be more closely scrutinized for Salmonella contamination than other feed ingredients.

Davies and Funk (1999) completed an extensive review of Salmonella epidemiology and control. They summarized that while feeds of animal origin receive the most attention as sources of Salmonella, it is now recognized that feeds of plant origin, such as soybean meal, are often contaminated with Salmonella. Data showing the incidence of Salmonella contamination in various feed ingredients in North America, Europe and the United Kingdom are shown in Table 6. These data suggest that all feed ingredients may be contaminated with Salmonella. Brooks (1989) demonstrated that the relative risk of Salmonella contamination in complete feed is less for animal proteins than for soybean meal, fishmeal and grain. Even if the Salmonella prevalence in animal proteins is equal to or exceeds that of other ingredients, animal proteins pose two- to threefold less risk of contaminating complete feed, because animal proteins typically have much lower (2 to 5 percent) inclusion rates than other ingredients (Table 7).

More than 2 200 different serotypes of Salmonella have been identified and only a few of these cause disease in humans or animals. Almost all of the Salmonella serotypes that have been identified in animal proteins are innocuous and do not cause disease (Davies and Funk, 1999). Furthermore, dried animal proteins do not provide a favorable environment for Salmonella organisms to proliferate, primarily because the water activity is too low. Figure 3 illustrates this point. Salmonella choleraesuis (a human pathogen) remained viable in meat and bone meal for less than two days after inoculation. In order to limit Salmonella (or other pathogenic organisms) in meat and other animal products, it is necessary to control the most important sources of contamination first. Feed is not the most important contributor to Salmonella contamination of these products. Data collected from commercial swine production facilities in the United States suggest that employees, cats, rodents, insects and environmental factors are much more important Salmonella reservoirs than feed (Table 8). Drinking water had more than a five-fold greater incidence of Salmonella than feed.

TABLE 4
Summary of potential health risks for various methods of handling animal by-products

^a Adapted from United Kingdom Department of Health, 2001.

TABLE 5
Efficacy of the United States’ rendering system in the destruction of pathogenic bacteria

^a Trout et al., 2001. Samples from 17 different rendering facilities taken during the winter and summer. ^b Percent of the number of samples found to be positive for pathogens out of the total samples collected.

TABLE 6
Incidence of Salmonella in feed ingredients

^a Beumer and Van der Poel, 1997; ^b Sreenivas, 1998; ^c McChesney et al., 1995; ^d Canadian Food Inspection Agency, 1999; ^e Brooks, 1989

TABLE 7
Relative risk of Salmonella contamination in complete feed^a

^a Brooks, 1989

Figure3. Salmonella choleraesius viability in mammalian bone meal (MBM)^a (7 to 25 percent moisture) and stored at 28.8^OC. ^aSutton et al. 1992

TABLE 8
Reservoirs of Salmonella contamination on Illinois swine farms.^a

^a Weigel et al. 1999.

These data all clearly demonstrate that animal proteins should not be the primary focus of concern in feeding programs designed to reduce the incidence of Salmonella. Why then, is Salmonella in feed ingredients, especially animal proteins, scrutinized so closely? - Because of perception - not fact. Requiring all animal proteins, or even all feed ingredients, to be Salmonella free has little impact on overall food safety without controlling the more important sources of contamination. Salmonella reduction/prevention is a farm - to - plate issue affecting all segments of the feed manufacturing, animal production, meat processing and retail meats industries.

Bovine spongiform encephalopathy (BSE)

What is BSE (‘Mad Cow Disease’)? ’Mad Cow Disease’ is an inaccurate term used to describe Bovine Spongiform Encephalopathy (BSE), because cows do not appear ’mad’ or ’crazy’ when they have the disease. This was a term coined by the news media in order to gain public attention and sensationalize the story. BSE is a more appropriate and accurate term to use when the disease is discussed. BSE is one of several related diseases that affect a number of different animal species and humans. These diseases are collectively called transmissible spongiform encephalopathies (TSEs).

BSE is a chronic degenerative disease that affects the central nervous system of cattle. The only positive cases detected outside of the United Kingdom and Mainland Europe were reported in Japan in late 2001. The incubation period is thought to be between two and eight years and it has been associated with a new form of Creutzfeldt-Jakob Disease (CJD) in humans. CJD has been recognized for many years as a sporadic disease that affects about 1 person per million. New variant Creutzfeldt-Jakob Disease (_vCJD) differs in etiology and it affects people at a younger age.

Fortunately, BSE is not easily passed from animal to animal, so it is not a contagious disease. It also affects specific tissues in cattle and is confined primarily to the brain, spinal cord and a few other tissues. Muscle and fat do not appear to be affected by the disease and are considered to be safe.

Why is BSE a growing concern? BSE is a complex disease that is poorly understood, even by the scientists who have worked in the field for many years. At least six different theories are used to explain its cause and transmission. A complete understanding of the disease is hampered by the long incubation period (up to 8 years for cattle). As a result, reporters, activists and some scientists and government officials consider theories and assumptions as fact. This combined with innuendo and the sensationalism associated with a possible link between BSE and human disease has created undue concern and panic among consumers. BSE is also compatible with the anti-meat and organic food agendas of certain activist groups in the United States and in Europe. These groups are organized and well funded and have developed focused media campaigns in order to advance their causes.

No single theory has been proven to explain the cause of BSE and/or _vCJD. Each theory can be supported by circumstantial, experimental or epidemiological evidence. However, until more is understood about the disease, theories will continue to be used to explain the cause. It is clear that abnormal prion proteins are involved in the disease. However, their role is not completely clear, so it is difficult to determine whether prion proteins cause disease or are an effect produced by some unidentified infectious agent or toxin.

Recognize regional differences. Efficient control and surveillance systems around the world make it possible to successfully manage the BSE issue. In general, BSE remains a regional disease and is largely confined to the United Kingdom and Mainland Europe. In the case of Japan, the cattle found to be positive for BSE were assumed to have contracted the disease through eating meat and bone meal that was exported from the United Kingdom or Mainland Europe where BSE had previously occurred. Therefore, animal proteins from the different countries where BSE has not existed represent a different risk than countries having the disease. The North American countries have implemented good BSE prevention efforts. Even though other transmissible spongiform encephalopathies (TSE), such as Scrapie in sheep and chronic wasting disease (CWD) in deer and elk exists in these countries, these diseases have been shown to differ in their etiology from BSE. Australia and New Zealand are free of these diseases.

Situation in the United States. The United States differs from Europe. A number of differences between the United States and Europe, in terms of livestock feeding and rearing practices, livestock demographics and governmental programmes, exist with respect to BSE risk assessment.

Sheep and cattle numbers in the United Kingdom are more concentrated than in the United States (Table 9). The United Kingdom is roughly the size of the State of Oregon and it has about four times more sheep than the entire United States. In addition to a dense sheep population, the United Kingdom also has more than 11 million cattle. As a result, there are almost 3 sheep for each bovine in the United Kingdom and 12 bovines for every sheep in the United States. The United Kingdom and the rest of the European Union have similar livestock demographics.

TABLE 9
Cattle and sheep demographics of United Kingdom, European Union and United States

Because vegetable protein sources are not as readily available in Europe as they are in the United States, ingredients used to provide supplemental protein in animal feeds have differed for many years. Compared to the United States, rendered animal proteins have historically been used at much higher concentrations in animal feeds in Europe. Further, animal proteins in Europe were commonly added to veal calf feeds and fed to cattle as young as two days old. Most United States’ beef production is concentrated in commercial feedlots where cattle are fed low forage rations consisting primarily of soy and corn. However, few feedlots exist in Europe and cattle are fed primarily on grass with protein supplements. Thus, the beef industry in Europe consists primarily of veal meat and older beef. Because, sheep are the most common ruminant animal in Europe, rendered animal proteins contained a higher proportion of sheep material than in the United States. Assuming that all rendered sheep protein was fed to dairy cows, those in the United Kingdom would consume 1.54 kg of sheep derived protein per day compared to only 79 grams in the United States. This comparison is even more dramatic because the US renderers voluntarily stopped processing sheep material prior to 1995.

Some scientists believe that BSE originated from Scrapie, a TSE that has been known to affect sheep for more than 300 years. Given the differences in sheep concentration and production statistics between the United States and Europe, the risk of BSE occurring in the United States is markedly lower than in Europe. When differences in feeding practices are also considered, the level of risk is further decreased.

The ’Triple Firewall’ strategy. The United States developed a series of ’firewalls’ to prevent BSE from occurring within its borders. The United States’ risk analysis approach was very different from that used in Europe, primarily because United States’ officials recognized from the beginning that zero risk was not attainable. The United States programme is a progressive and continuously evolving one designed to proactively prevent the introduction of BSE (import restrictions), prevent amplification, should the disease ever be introduced into the United States (ruminant feed ban) and implement an aggressive targeted detection system (surveillance). All steps were based on science and have been the result of joint efforts among governmental agencies and all segments of the beef, dairy, feed and rendering industries (Table 10).

Brain tissue from more than 22 900 cattle were tested and found to be negative for BSE between 1990 and February of 2002. This programme has primarily focused on the segment of the cattle population that represents the greatest risk for BSE. As scientists in Europe have learned more about the cattle most likely to test positive for the disease, surveillance in the United States has been adjusted accordingly. The most recent modification to include ’downer cows’ resulted in a substantial increase in sample submissions. Target sample numbers for the year 2002 are double the targets for the preceding year.

The record keeping requirements that rendering companies and the feed industry are required to comply with also require a high degree of traceability for animal proteins. Regulated by the FDA, it is possible to trace finished proteins and fats from collection to use.

Actions by the US rendering industry. The United States’ rendering industry fully supports BSE prevention programmes and efforts developed by the United States’ FDA, Animal and Plant Health Inspection Service (APHIS) and other federal and state governmental agencies. The rendering industry is committed to achieving 100 percent compliance to the FDA ban (No. 21 CFR 589.2000) which prohibits the feeding of mammalian proteins (with some specified exemptions) to cattle and other ruminant animals.

The rendering industry has been actively involved in programmes to prevent BSE in the United States since before 1995, when renderers voluntarily stopped rendering sheep material. This was to prevent any scrapie-infected material from entering the food chain, especially through feed for ruminant animals.

When the FDA first considered preventative measures in 1996, renderers and cattle producers voluntarily stopped using meat and bone meal derived from ruminant animals in cattle feed. This later became official when the FDA published the rule prohibiting the use of these materials in feeds intended for cattle and other ruminant animals. The rendering industry was actively involved in preparing this rule and fully supported it from its introduction in 1997. The only meat and bone meal permitted for use in ruminant animal feed in the United States is material that comes from processing plants that slaughter or process only non-ruminant animals. material is prohibited from use in feeds for cattle and other ruminant animals.

TABLE 10
Summary of United States BSE prevention efforts

If the raw material cannot be verified to be of 100 percent non-ruminant origin, then the resulting finished. While hazard analysis critical control point (HACCP) programmes target known hazards that can be eliminated or controlled through the rendering process, they also include in-plant enforcement of policies that apply to the acceptance or rejection of raw material. This provides further assurance that material from suspect cattle (such as those being tested for BSE through the APHIS surveillance programme), sheep, goats and other animals susceptible to TSEs are not received and processed.

The FDA feed ban includes requirements that finished products are clearly labeled and records of raw material receipts and finished product sales be kept and made available for inspection by the FDA. This allows the FDA to verify the source of raw materials and verify compliance to the feed ban among feed manufacturers, dealers, distributors and end users. For renderers who process proteins exempted under the feed ban, safeguards to prevent cross-contamination must be demonstrated in practice and in writing.

The American Protein Producers Industry (APPI) recently introduced a certification programme for rendering companies, to verify compliance to the feed ban, based on inspections by third-party auditors. The goal is to have 100 percent participation among all rendering companies in the United States and 100 percent compliance to the feed ban. This program does not replace FDA inspections, although results are available for FDA review. The American Feed Ingredient Association (AFIA) developed a similar programme for commercial feed manufacturers. The American Meat Industry (AMI) has also developed a programme for cattle producers to certify that the cattle they are offering for slaughter have been fed in accordance with FDA regulations.

Harvard Risk Analysis. The United States Department of Agriculture commissioned the Harvard Center for Risk Analysis at the Harvard University School of Medicine to evaluate the potential for BSE to occur in the United States. The ’Harvard Risk Analysis’ was made public in November 2001 (Cohen et al., 2001). The study concluded that the United States is highly resistant to any introduction of BSE or similar disease. Further, BSE is extremely unlikely to become established in this country because measures taken by agencies of the United States’ government were and continue to be effective at reducing the spread of BSE. The feed ban introduced by the FDA in 1997 to prevent amplification of the disease should it ever occur in the United States, was considered to be one of the most important safeguards. The full report is available on the USDA web site located at http://www.aphis.usda.gov/oa/bse/.

Species that animal proteins are derived from differ in risk. Specie and type of tissue used to produce animal protein affects the risk from BSE. Neither pork nor poultry derived proteins have been implicated as potential sources of the BSE agent. Europe is in the process of classifying its animal by-products in case its total ban on feeding animal proteins is lifted. Materials derived from non-ruminant animals approved for human consumption may eventually be available for use in animal feeds. Other countries are not presently classifying animal by-products, although some additional actions may occur in the United States as the various regulatory agencies work to further strengthen BSE prevention efforts, even though additional regulations are not scientifically warranted.

A number of governmental agencies around the world are working to develop testing methodologies to assist them in identifying the type of material from which animal proteins were derived. For example, it is possible to identify species-specific DNA using polymerase chain reaction (PCR). Species-specific DNA can be identified even if the DNA is partially degraded. It is also possible to differentiate skeletal muscle in protein meals, using ELISA. Detection limits and validation procedures are being completed for these technologies. As these issues are resolved, acceptable thresholds will be established by the appropriate regulatory agencies. At present the unit sample cost is projected to be moderately high. However, as the technology is adopted, the costs are expected to decrease.

Acceptable testing methodologies to identify restricted use proteins in feed for cattle and other ruminant animals will make it simpler to verify compliance to feed bans and restrictions. These regulatory tools will make it possible to validate that animal proteins are used safely in feeds, even in countries known to have BSE present. The greatest challenge will be in establishing uniform threshold limits for the presence of prohibited materials in these feeds.

Transmission studies. The majority of experiments designed to study transmission of BSE and other TSEs among animals of the same species or from specie to specie, used the intra-cranial route to introduce raw nervous tissue directly into the brain of the test animals. Oral transmission is assumed to be much less effective because intestinal absorption followed by transport and concentration of the infectious agent in the target tissues must occur. Therefore, oral exposure (i.e. via contaminated feed) is generally assumed to be one hundred thousand-fold less effective than direct exposure by the intra-cranial route (Schreuder et al., 1998). Given the potential losses that may occur via oral exposure, a large number of infectious units must be consumed in order for the disease to develop. For humans, the oral infectious dose (ID₅₀) is estimated to be 10¹³ BSE prion molecules, which is a very large dose compared to known bacterial and viral pathogens (Gunn, 2001). While heat processing does not destroy the infectious agent, processing at 134° C for 3 minutes caused a 2.5 log reduction in infectivity (Schreuder et al., 1998). Therefore, the risk of spreading BSE by feeding fully processed animal proteins is extremely low.

Pearl (2001a) summarized several oral challenge studies that are in progress in the United States and in the United Kingdom. Because BSE has not been found in the United States, BSE challenge studies can only be conducted in Europe. Scientists in the United States use scrapie and CWD infected material in their challenge studies.

Chickens orally challenged with BSE. A 57- month study to determine the susceptibility of chickens to BSE was conducted in the United Kingdom. Chickens were challenged with BSE infected brain tissue by intra-cranial, intra-peritoneal and oral (esophageal tube) routes. No infectivity was found in any of the chicken tissue assayed upon completion of the study, regardless of the route used to introduce infective material. These results suggest that BSE is not transmitted to chickens.

Cattle orally challenged with Scrapie. An 8-year study conducted in the United States determined the effects of orally or intra-cranially challenging 34 calves with rendered proteins and fats from scrapie infected sheep. There was no evidence of oral transmission at any time during the course of the study. A second experiment, also in the United States, orally challenged 17 calves with rendered scrapie positive brain tissue from sheep. All animals were negative for BSE (and scrapie) after 8 years. However, 9 calves challenged with intra-cerebral inoculations were positive for a scrapie-like infection.

Cattle orally challenged with chronic wasting disease. A total of 26 calves were inoculated (oral or intra-cranial) with brain tissue from CWD infected mule deer in 1997. Three calves from each challenge group (oral or intra-cranial) were sacrificed in 1999 and found to be negative for disease. The remaining animals are still alive and all appear healthy.

HAZARD ANALYSIS CRITICAL CONTROL POINT

Rendering companies in the United States, Europe and other countries have adopted HACCP programmes as an important component of their biosecurity and food safety programmes. HACCP programmes require an evaluation of the entire rendering process, identification of potential hazards (such as Salmonella), identification of critical points in the process where the hazard(s) can be controlled and development of procedures to control these processes and ensure destruction or removal of the hazard. Additional controls may also be included at various points in the process to assure quality (QA) of the finished product(s). A generalized HACCP - QA programme for a typical rendering facility is shown in Figure 4. It is anticipated that the FDA will require that the US rendering industry use HACCP programmes within the next two years.

Dioxins

Concern with dioxin increased because of a clearly criminal act that occurred in Belgium. Prior to this event, most rendering companies developed and implemented sampling and testing protocols to ensure that finished fat and animal proteins were not contaminated with potentially hazardous compounds, such as pesticides and PCB’s. The rendering process does not produce dioxins, as shown in Table 4. Because of the extremely expensive nature of analyzing production samples for dioxins, testing protocols test for PCB’s which are recognized by regulatory agencies all over the world as indicators of dioxins.

Figure 4. Basic production flow-chart with HACCP and quality control points

Dioxins can enter rendered products by one of two methods: (1) the most likely is by accidental or intentional contamination and (2) the presence of dioxins in animal tissues. Maximum tolerances for PCB’s already exist. The European Union and the United States FDA are both considering adoption of maximum tolerance levels for all dioxins. As sensitive and inexpensive analytical procedures to test for dioxin in the parts per trillion range are developed, rendering companies will readily adopt the technology to ensure that finished rendered products are safe from dioxins.

SUMMARY

Animal proteins are an important class of ingredients for animal nutritionists to use in feed formulas. The United States’ rendering industry produces nutrient rich products that are highly digestible, do not contain anti-growth factors and are safe to use in livestock, poultry, pet and aquaculture feeds.

The rendering process kills Salmonella and other food pathogens, although post process contamination can still occur. All feed ingredients may be contaminated with Salmonella.

However, reservoirs of Salmonella present in animal production facilities are a much greater hazard to food safety than feed ingredients. Until these sources of contamination are controlled, little benefit to controlling Salmonella prevalence in feed ingredients will be realized.

Bovine spongiform encephalopathy continues to be surrounded by myth and misperceptions. If feed-contaminated animal proteins spread this disease, countries that have never reported an incidence of BSE represent a much lower risk than those where the disease has occurred. BSE has never been reported in the United States, despite the presence of a progressive surveillance programme that began in 1990. The United States complimented surveillance with import bans and restrictions to prevent introduction of BSE into the United States. In the event that BSE was ever found in the United States, the FDA preemptively instituted a ban on the feeding of meat and bone meal from ruminant animals to cattle and other ruminants to prevent amplification and spread of the disease. Additionally, the rendering industry voluntarily stopped processing sheep and goat material and recently introduced an industry wide programme to verify compliance with the FDA feed ban using third-party auditors.

Differences between the United States and Europe in livestock demographics, feeding practices and governmental policies pertaining to BSE make the occurrence of BSE in the United States unlikely. Oral transmission via infected feed has not been proven and would require exposure to an extraordinarily large number of infectious molecules. The sum of all of these efforts and statistics make it highly unlikely that BSE will occur in the United States. To date, BSE remains a European phenomenon, with 99 percent of all cases in the world occurring in the United Kingdom.

Based on current accepted theories, the specific tissues and animal specie from which the tissues were derived as well as the country or regions of the world all interact to influence the risk of BSE. As methodologies are developed that allow identification of the specie and type of tissue that animal proteins are derived from, it will be much simpler for governments to regulate the feeding of animal proteins.

The World Rendering Industry supports programmes to prevent and control BSE. The US Rendering Industry fully complies with the United States Food and Drug Administration’s ban on feeding certain mammalian animal proteins to cattle and other ruminants. Rendering companies also support industry programmes developed to certify compliance with this rule and participate in the APPI compliance certification programme, using third-party auditors.

REFERENCES

Batterham, E. S., et al. 1990. British Journal of Nutrition, 64: 679.

Beumer, H. & Van der Poel, A. F. B. 1997. Feedstuffs, Dec. 29.

Brooks, P. 1989. Technical Service Publication, National Renderers Association, Inc. Canadian Food Inspection Agency, 1999.

Cohen, et al. 2001. Report from the Harvard Center for Risk Analysis, Harvard School of Public Health.

Dale, N. 1997. Journal of Applied Poultry Research, 6: 169.

Davies, P. R. & Funk, J. A. 1999. Proc. 3^rd International Symposium on the Epidemiology and Control of Salmonella in Pork, August 5-7. p. 1-11.

Firman, J. D. 1992. Journal of Applied Poultry Research, 1: 350.

Franco, D. A. 1993. Proceedings of the 54^th Minnesota Nutrition Conference. p. 21-35.

Gunn, M. 2001. Irish Vetinerary Record, 54(4): 192.

Jorgensen, H., Sauer, W. C. &. Thacker, P. A. 1984. Journal of Animal Science, 58: 926.

Knabe, D. A. 1996. In: The Original Recyclers. p. 176-202. APPI, FPRF and NRA.

McChesney, D. G., Kaplan G. & Gardner, P. 1995. Feedstuffs, Feb. 13. p. 20 & 23.

NRC. 1994. Nutrient Requirements of Poultry (9^th Rev. Ed.). Washington D. C, National Academy Press.

Parsons, C. M., Castanon, F. & Han, Y. 1997. Poultry Science, 76: 361.

Pearl, G. G. 2001a. Directors Digest # 308. Fats and Proteins Research Foundation.

Pearl, G. G. 2001b. Proceedings Mid-West Swine Nutrition Conference. Sept. 5. Indianapolis, IN, USA.

Schreuder, B. E. C., et al. 1998. Veterinary Record, 142: 474.

Sreenivas., P. T. 1998. Feed Mixing, 6(5): 8.

Sutton, A. L., Scheidt, A. B. & Patterson, J. A. 1992. Final Research Report. Fats and Protein Research Foundation.

Trout, H. F., Schaeffer, D., Kakoma, I. & Pearl, G. 2001. Directors Digest #312. Fats and Proteins Research Foundation.

United Kingdom Department of Health. 2001. A rapid qualitative assessment of possible risks to public health from current foot and mouth disposal options - Main Report. June.

Weigel, R., Barber, D., Isaacson, R. E., Bahnson P. B. & Jones, C. J. 1999. Proceedings 3^rd International Symposium on the Epidemiology and Control of Salmonella in Pork. August 5-7 p. 180-183.