Animal Feed Contamination

Effects on Livestock and Food Safety

J Fink-Gremmels

• Publisher: Woodhead Publishing
• Year: 2012
• ISBN:
  9780857093615
• Topic: Tecnologia e ingegneria
• Subtopic: Scienze dell'alimentazione

The production of animal feed increasingly relies on the global acquisition of feed material, increasing the risk of chemical and microbiological contaminants being transferred into food-producing animals. Animal feed contamination provides a comprehensive overview of recent research into animal feed contaminants and their negative effects on both animal and human health.Part one focuses on the contamination of feeds and fodder by microorganisms and animal by-products. Analysis of contamination by persistent organic pollutants and toxic metals follows in part two, before the problem of natural toxins is considered in part three. Veterinary medicinal products as contaminants are explored in part four, along with a discussion of the use of antimicrobials in animal feed. Part five goes on to highlight the risk from emerging technologies. Finally, part six explores feed safety and quality management by considering the safe supply and management of animal feed, the process of sampling for contaminant analysis, and the GMP+ feed safety assurance scheme.With its distinguished editor and international team of expert contributors, Animal feed contamination is an indispensable reference work for all those responsible for food safety control in the food and feed industries, as well as a key source for researchers in this area.

• Provides a comprehensive review of research into animal feed contaminants and their negative effects on both animal and human health
• Examines the contamination of feeds and fodder by microorganisms and animal by-products
• Analyses contamination by persistant organic pollutants, toxic metals and natural toxins

1

Introduction to animal feed contamination

J. Fink-Gremmels, Utrecht University, The Netherlands

Abstract:

Global acquisition of feed materials has become common in order to achieve economically viable production of animal feeds. At the same time this globalization increases the risk for potential microbiological and toxicological contaminants that determine the quality and nutritional value of feeds, but more importantly also the safety of animal-derived foods such as milk, meat and eggs. Quality control programmes require a stratified multidisciplinary approach addressing the entire food chain, from agricultural sourcing through processing to animal nutrition and assessment of animal and human health risks.

Key words

food and feed safety

concentrated animal feed operations

microbiological and chemical hazards

socio-economic impact of feed production

risk management and communication

1.1 Animal feed production

Animal feed production is a silent industry that only reaches newspaper headlines at times of crisis; these crises include, for example, the emergence of unknown pathogens in livestock, such as prions (causing transmissible bovine encephalitis) (Sakudo et al., 2011), unexpected sources of dioxin contamination of milk, meat and eggs (Hoogenboom et al., 2010; O’Donovan et al., 2011) and the presence of residues or unauthorized substances such as melamine in milk, milk products and animal feeds (Qin et al., 2010).

The animal feed industry, however, is a truly global business of great economic importance. It is linked to concentrated animal feeding operations, with ever-increasing farm sizes trying to meet the increasing protein demands of the growing world population. Intensified animal production required the development of new principles of animal breeding, animal nutrition and feed composition (Thorne, 2007). The most impressive example of these changes is probably that of the broiler chicken, whose body weight at hatching is increased by up to 5000 times in the short 35 days of a broiler’s lifespan. Diets for monogastric animals such as pigs and chickens may contain up to 60% cereal grains to achieve high productivity. This implies that in this case animal nutrition is in competition with resources that can be also used for human nutrition (Weckwerth, 2011). The grazing of cattle, originally widespread, has been substituted by dairy farms at which the cows are given an individualized diet containing up to 80% of concentrates, mixed according to the availability of energy-rich feed materials on the world market. The growing production of bioethanol/biodiesel adds to this division of resources and has resulted in a dramatic increase in the world market price of many feed materials such as soybeans, cereal grains and oil plants (Robertson and Swinton, 2005). The socio-economic impact of this competition is contributing to the global debate on the prudent use of the available natural resources and farmland and the prevention of land grabbing by strong economies such as Europe, where the net imports totalled more than 38 million ha in 2009 and 2010 (www.farmlandgrab.org; United Nations, 2010).

Considering these recent developments it is clear that the major concern in feed production is the availability of sufficient supplies of feed materials. As these are becoming increasingly limited, animal nutritionists have to meet the challenge of exploring the special dietary needs of high-producing animals while still ensuring that feed supplies remain safe and cost-effective. The high demands for an optimal feed utilization rely not only on diets able to provide the animal with all essential macro- and micro-nutrients but also require feed materials free of anti-nutritive factors and microbiological or toxicological hazards. Subsequently, feed safety has emerged as one of the most important parameters affecting animal husbandry, health and productivity.

1.2 Feed safety

1.2.1 From farm to fork

At the beginning of this millennium the European Commission presented its White Paper on Food Safety (EC, 2000; COM/99/0719 final) which was intended to improve transparency and safety along the entire food production chain. The term from farm to fork signalled the responsibilities of all stakeholders in the production chain to take effective measures to minimize risks to both animal and human health (www.ec.europa.eu/food/omtro_en.htm). Any food that reaches the consumer should be free from hazards such as microbiological or chemical (abiotic) contaminants. For both microbiological and toxicological hazards, the responsible international authorities (FAO/WHO and the Codex Alimentarius Commission (CAC), the US Food and Drug Administration (FDA), the US Environmental Health Protection Agency (EPA) and the European Food Safety Authority (EFSA)) present risk assessments and establish maximum tolerable limits for contaminants, which serve as the reference for quality assurance programmes. In the initial phase of the production of foods from animal origin, feed quality is the most crucial factor that can lead to exposure of animals to undesirable contaminants. Therefore, within the European feed legislation it is stated that ‘products intended for animal feed must be sound, genuine and of merchantable quality and therefore when correctly used must not represent any danger to human health, animal health or to the environment or adversely affect livestock production’ (Commission Directive 2002/32/EC).

The feed industry has endorsed this need for transparency in the sourcing and processing of feed materials and in the use of feed supplements and additives. The latter require premarketing approval by the competent authorities prior to their use in feeds for farmed animals, including fish. Embedded in the One-Health Concept, integrated quality control programmes along the entire production chain should reduce the risk for animals and humans. It should also be mentioned that quality controls at the start of a production chain are a prerequisite for an economically viable agro-industry, thus preventing the need for rejection and destruction of food that is considered unfit for human consumption.

1.2.2 A truly multidisciplinary task

The assessment of feed safety is an extremely complex issue that has long been underestimated. Feed safety assessment in fact requires expertise in multiple disciplines such as agriculture and crop production, feed processing and technology and animal nutrition. Added to these basic disciplines, feed safety assessment also requires an understanding of microbiology and biosecurity measures, toxicology and animal health sciences (veterinary medicine) and ultimately experience in risk assessment methodologies.

Risk assessment has evolved into a well-structured scientific approach, with transparent rules, extensive data sourcing and distinct statistical procedures. The four essential elements of a quantitative risk assessment are hazard identification and characterization, exposure assessment and risk characterization. The ultimate outputs of risk assessment procedures are health-based guidance levels expressed as acceptable daily intake and tolerable weekly intake levels that carry no or a negligible risk for human health (Dorne, 2010). This stratified procedure must also be implemented in the assessment of feed safety for feeds used in food-producing animals. In addition, public interest has today extended to include the impact of large-scale animal production and feed sourcing on the environment and the role of farmers as eco-agricultural stewards (Thorne, 2007; Sachs, 2010).

1.2.3 Animal health and welfare

As previously mentioned, feed material may be the source of microbiological and chemical hazards (Frazzoli and Mantovani, 2010). Technical processes such as cleaning, disinfection and heating are generally employed to damage and destroy microbiological contaminants that could otherwise cause contamination of food derived from these animals. These processes are cost-intensive and the efficacy of preventive measures needs to be established and controlled for any feed material and compound in feed. Hence the limitations are obvious: highly process-resistant agents such as prions (TSE-BSE) require inactivation processes that compromise the palatability and nutritional value of feed materials (animal by-products) (Sakudo et al., 2011). The innate resistance of many bacteria (anaerobic, spore-forming organisms) to inactivation procedures such as heat and acid treatment leads to an ever-present risk of viable pathogens being present in individual feed batches, which are then introduced into animal facilities. Perhaps the most prominent example of an unresolved, long-lasting problem in feed hygiene is contamination with enterobacteriaceae such as Salmonella, Campylobacter and anaerobes (Clostridium spp.) in poultry units (Mataragas et al., 2008; Fosse et al., 2009).

Problems relating to toxic and anti-nutritive chemical substances are on an even wider scale. The EC European Catalogue of Feed Materials currently covers more than 700 entries, and all of these feed components may be potentially contaminated with one or more toxic substance(s). In the past, interest focused particularly on environmental pollutants and contaminants such as persistent organic pollutants (POPs), present in a broad variety of feed materials and able to accumulate in animal tissues. This is also true of dioxins and dioxin-like polychlorinated biphenyls and of many other polyhalogenated chemicals that are used in industrial processes and hence reach the environment (Fries, 1995; Antignac et al., 2006; Yu et al., 2010) Toxic heavy metals (cadmium, lead and mercury) and other chemical elements (arsenic, chromium, copper and zinc) occur naturally, but industrial processes may increase their concentration in distinct geographic regions, leading to their accumulation in plants that are consumed or harvested as feed for animal consumption (Schauder et al., 2010; Lopes et al., 2011) Moreover, recently identified new endpoints of toxicity, such as for example developmental neurotoxicity of methyl-mercury, gain increasing attention (Dorne et al., 2011; Farina et al., 2011).

Natural toxins such as toxic plant metabolites (i.e. glycosinolates, saponins, alkaloids, including pyrrolizidin alkaloids, and terpenes) and bacterial and fungal toxins (mycotoxins) have long been known to the veterinary professionals as causes of acute intoxications in individual animals, but have been largely ignored in risk assessment exercises. Their antinutritive properties and toxicological profile as substances with immunosuppressive and/or reprotoxic effects, however, have placed natural toxins high on the priority list for current risk assessment and statutory limits to protect animal health and performance. The risk assessment of such natural toxins is characterized by a high level of uncertainty as outlined in detail in the Opinions of the EFSA Panel on Contamina...