SECTION 1 Health hazards associated with animal feed

1 SECTION 1. Health hazards associated with animal feed USDA. Health hazards associated with animal feed SECTION 1. 3. INTRODUCTION t GPPE QSPDFTTJOH CZ QSPEVDUT BOE DP QSPEVDUT . Food safety hazards associated with animal feed t NJOFSBMT JODMVEJOH USBDF FMFNFOUT BOE CJOEFST . can be biological, chemical or physical. Each t BOJNBM CZ QSPEVDUT JODMVEJOH NFBU BOE CPOF . hazard is associated with particular sources and meal and fats;. routes of contamination and exposure. Risk t BRVBUJD QSPEVDUT JODMVEJOH GJTINFBM TIFMMGJTI . management must be based on a thorough fish by-products, seaweed and krill;. understanding of these characteristics. The role t GFSNFOUBUJPO CJPNBTT BOE ESJFE QSPEVDUT . of water as a potential source of hazards should t WJBCMF NJDSPCFT . not be overlooked. hazards may be introduced t TJMBHF BEEJUJWFT . with source materials or via carryover or conta- The following undesirable substances and micro- mination of products during handling, storage organisms are currently considered to be the and transportation.

2 The presence of a hazard most important: may also result from accidental or deliberate ( fraud or bioterrorism) human intervention. CHEMICAL SUBSTANCES. Risk management should be based upon prepa- Dioxins, dibenzofurans, and redness and prevention rather than reaction after dioxin-like PCBs (dioxins). detection of the problem. Important issues that Because of the ubiquitous presence of dioxins in have contributed to this evolution include: the environment, the threat of dioxin contami- (i) Bovine Spongiform Encephalopathy (BSE) nation posed by feed ingredients may originate and other prion diseases; from many different sources. Since the Bel- (ii) impact on food safety of antimicrobial use in gian dioxin crisis in 1999, dioxins have become animals; important considerations for feed safety. Since (iii) newly recognized undesirable substances: then, numerous cases of contamination invol- melamine, dioxins, dibenzofurans and ving dioxin from unexpected sources have been dioxin-like polychlorinated biphenyls (PCBs); reported.

3 This has shown that dioxins may be (iv) the presence of genetically modified orga- inherent to a product ( clay minerals), or nisms, crops and enzymes in feed; introduced during processing ( lime in citrus (v) by-products of new technologies ( bio- pulp). Dioxins can be introduced if contaminated fuel production) used in feed production; fuels are used in the drying of feed products;. (vi) radionuclides; for example treated wood, poor quality coal or (vii) development of aquaculture industries and contaminated fuel oil. Dioxins have also been the search for new/better aquaculture feeds; known to contaminate forage crops grown in (viii) feed (and food) as the target of bioterrorism; the vicinity of certain industrial processes ( and incinerators). (ix) emerging technologies, such as the use of Dioxins and dioxin-like PCBs are two related products of nanotechnology in feed. groups of toxic compounds, both comprising a (x) Selection of undesirable substances and number of congeners.

4 Each congener has its own micro-organisms of concern toxicity as expressed by the toxicity equivalence The following criteria have been used to select factor (TEF). hazards of current importance in feed: It has been postulated that most human expo- (i) relevance of the hazard to public Health ; sure to dioxins is as a result of foods of animal (ii) extent of the occurrence of the hazard; origin, which in turn may arise from the presence (iii) impact of the hazard on international trade of dioxins in animal feeds. Dioxins accumulate in in food and feed. fat to a high degree, so even extremely low levels Among others, the following feeds and feed of dioxin in feed can become significant over the ingredients are considered: lifetime of an animal and result in unacceptable t DPNQPVOE DPNQMFUF GFFET residues in human foods such as meat, milk, and t HSBJOT BOE PJMTFFET XIPMF BOE NFBMT. GSVJU BOE eggs. Toxicokinetic models have been developed vegetable by-products, including oils; to estimate the transfer rates of dioxins to animal t GPSBHF JODMVEJOH HSBTTFT IBZ BOE TJMBHF tissues (Van Eijkeren et al.)

5 2006). t EJSFDUMZ ESJFE QSPEVDUT F H CBLFSZ CZ QSPEVDUT. As such, implementing controls for dioxins t CJPGVFM CZ QSPEVDUT F H EJTUJMMFST HSBJOT XJUI in feed represents an important step towards solubles (DGS), dried distillers' grains with reducing dioxins in the food chain. In particu- solubles (DDGS) and glycerol); lar, screening programmes have indicated that Manual of Good Practices for the Feed Industry 4. dioxins may arise in feed via their presence in of the following transfers from feed to food: mineral sources, such as clays, recuperated copper aflatoxin B1 to liver, aflatoxin B1 to milk as sulphate, zinc oxide; food by-products; and fish aflatoxin M1, aflatoxin B1 to eggs as aflatoxicol;. by-products such as fish meal and fish oils. ochratoxin A to meat; deoxynivalenol to meat There is a need for development/improvement as DOM1; zearalenone to meat as zearalenol, of inexpensive and accurate screening methods. evaluating transfer rate and route of exposure in Feed and food exposure studies are necessary humans is restricted to aflatoxin B1 for animals to account for all sources of dioxin entering the producing milk.

6 Feed chain. Farmers should bear in mind that animals fed on aflatoxin contaminated feed do not show Mycotoxins: Aflatoxin B1 symptoms of aflatoxin toxicity. In the last decade, many studies have been Feeds most susceptible to aflatoxin are: conducted on mycotoxins. Most frequently occur- cereals (especially maize), cottonseed, peanut, ring mycotoxins (aflatoxin B1, ochratoxin A, zea- copra, palm kernel and rice bran but caution ralenone, fumonisin B1, deoxinivalenol, T-2 and is required with any feed products grown in HT-2) are currently considered for their effects on tropical and sub-tropical regions, particularly animal Health . where they are not dried or processed promptly However, when focusing on how mycotoxins after harvesting. Aflatoxin contamination is not play a role in food safety, attention should be homogeneous; it is therefore very important to limited to mycotoxins that are known to be trans- apply an appropriate sampling method.

7 Feeds ferred from feed to food of animal origin, as this having a significant aflatoxin contamination food represents a significant route of exposure should not be fed to dairy cows or other ani- for humans. mals producing milk for human consumption or Although the scientific community is aware to other food-producing animals. TABLE 1. Minerals, their sources and bioaccumulation in animal tissues Mineral Sources Bioaccumulation in animal tissues: Arsenic (inorganic) Sea plants, fish products and Fish supplemental minerals Cadmium Mineral supplements (such as phosphate, Kidney and liver zinc sources) Shellfish, oysters, salmon and fungi, have Forage/grains (depending on geographical the highest concentrations area) There are low concentrations in fruits, Manure, sewage, sludge or phosphate dairy products, legumes, meat, eggs and fertilizers can enrich soil poultry Lead Contaminated soil, lead paints, water Bone, brain and kidney from plumbing systems that contain lead, batteries Mineral supplements (copper sulphate, zinc sulphate, zinc oxide).

8 Lead is also a natural contaminant of calcium carbonate (limestone) in some regions Mercury/methyl mercury Anthropogenic contamination, fish meal Liver, kidney Fish, marine mammals Source: NRC. 2005. Mineral tolerance of animals. Washington DC, National Research Council Health hazards associated with animal feed SECTION 1. 5. There is some evidence to suggest that myco- could accumulate these substances, which are toxins can concentrate in dried distillers' grains extremely persistent and which decompose very with solubles (DDGS) during the processing of slowly. Contaminated animal products can cause grains for ethanol production. They also concen- food safety issues for humans. trate in cereal bran. Microbiological hazards Heavy metals The primary sources of microbiological hazards in Cadmium is a ubiquitous contaminant that is pre- feed are contaminated pasture land, forages and sent in many feed and feed ingredients, in parti- animal and vegetable protein meals fed directly cular minerals, and forages grown near smelting to and mining areas.

9 Arsenic and mercury are heavy metals which are widespread in the environment Brucella and which can be found in many feeds, in par- In some countries, where Brucella infection ticular in feeds of marine origin. Lead is also a occurs, infected ruminants can deliver offspring ubiquitous contaminant. Table 1 summarizes the or abort in fields that are grazed or from which most relevant minerals, their sources and bioac- pasture is harvested and used for animal feed. It cumulation in animal tissues. is well known that the placentas of infected ani- mals contain high levels of Brucella micro-orga- Veterinary drugs nisms. If contaminated forage is fed to milking As veterinary drugs may be a potential risk for animals, the micro-organisms may be excreted food safety, they should be used according to in their milk. If this milk is not pasteurized prior good practices in the use of veterinary drugs to consumption by humans, it is a risk to food (GPVD) (OIE, 2007).

10 Safety. Residues of veterinary drugs can be present in feed when ingredients of animal origin (terres- Salmonella trial and aquatic) are used, but this is not a very Salmonella is still of worldwide human Health significant route of exposure. concern. It is clear that infection in animals has Veterinary drug residues may be found in food a direct impact on transmission to humans via products as a result of the carryover of veterinary food of animal origin. Contaminated feed might drugs in feed during feed production. Therefore, represent an important route of exposure to it is important to follow the Code recommenda- Salmonella. tions (flushing, sequencing, cleaning) when feed for food-producing animals is produced after the Endoparasites production of a medicated feed. Some endoparasites of animals, such as Echi- It is also important to take into account the nococcus, Toxoplasma gondii, Cisticercus and illegal use of drugs in animal feed which may Trichinella, present a risk to human Health , result in unsafe residues in meat, milk or eggs and ingestive stages can contaminate animal ( chloramphenicol/nitrofurans in shrimps and feeds.)