Controlling pathogens becomes a priority

Ensuring that feed is free from pathogen contamination is a key component in any livestock producer’s strategy to ensure that they comply with legislation designed to provide consumers with higher standards of food safety.

By Roger Mann, Anitox, United Kingdom

Food safety is a growing issue for livestock producers all over the world, particularly in the European Union where legislations such as EU Zoonoses Regulation EC 2160/2003 are promoting ever-higher standards. This requires all EU member states to take effective measures to detect and control Salmonellas of public health significance in farmed species. These mig ht present a potential risk of transmitting the bugs and other zoonotic agents (diseases that can spread from animal to humans) to humans. However, all those supplying meat products to customers within the EU must also comply.

Concurrent with legislation focusing on this area, a number of other critical factors are converging. Globally, dietary patterns are constantly changing. Incidences of food safety and other public health issues are also increasing, and consumers are becoming more aware of what they eat and how it is produced. Additionally, retailers are making ever more stringent demands on suppliers. All of these factors are together adding pressure on producers to introduce higher standards of pathogen control. The European Food Safety Authority (EFSA) report on zoonoses, ‘The Community Summary Report onTrends and Sources of Zoonotic Agents in the European Union in 2007’,highlights Salmonella, Campylobacter and Listeria as the main causes of food-borne illness in humans. Campylobacteriosis was the most frequently reported, showing an increase to 200,507 cases in the EU-27. Frequently detected in live poultry, pigs, cattle and fresh poultry meat, Campylobacter was the most common zoonotic agent, found in 26% of samples tested. In second place was Salmonella, which caused 151,995 cases. Salmonella-species bacteria were most often found in fresh poultry (5.5% of samples) and pig meat (1.1%), while in live food-producing animals it was most frequently detected in poultry.

A mandatory control programme for Salmonella was introduced in breeding poultry flocks in 2007, and of the 27 EU countries, 15 indicated a prevalence level below the 1% reduction target. Legislation in respect of layers was in place by January 2008 and reduction targets were implemented in January 2009. To comply, the UK, for example, will need to achieve a 10% annual reduction in the number of flocks of adult laying hens infected with Salmonella enteritidis and Salmonella typhimurium – the country’s baseline figure being 8% of Salmonellas of human health significance.

Edwina Curry effect

Zoonoses have only become a focus of attention in recent years. Until the early 1990s when UK Member of Parliament Edwina Curry famously caused public panic by overstating the risk to human health from eating eggs containing Salmonella, the subject of pathogen control received little attention. However, that incident caused major retailers to insist on higher standards from producers as well as the entire livestock industry to address their concerns.

Salmonella cannot be entirely eradicated, but it can be controlled. Immediately after ‘the eggs scandal’, Anitox conducted an investigation into the prevalence of Salmonella, bacteria and mould in animal feedstuffs and feed ingredients. This worldwide field study identified that some microbial contaminants were causing problems in poultry and livestock. Salmonella, for example, was found in 36% of complete feed products, while levels in individual ingredients were often much higher, with bacteria or mould present in up to 96% of complete feeds.

While these can cause significant productivity losses in poultry and livestock, bacterium such as Salmonella cause illness or even death in susceptible humans who consume contaminated animal products such as eggs, meat and milk. The variables that compound the problems caused by this robust, persistent organism include environmental contamination, susceptible animals and poor standards of hygiene, disinfection and bio-security. With this knowledge, Anitox developed the Termin-8^® pathogen control programme for finished feed and raw materials. This enables feed manufacturers to dramatically improve their hygiene, thereby resulting in safer, pathogen-free feed at the point of manufacture and throughout the handling, storage and transportation phases.

Increasing problem

As the world becomes more affluent and demand for meat-based protein escalates, so the incidence of food safety-related issues is increasing, bringing with it more legislation. As part of the EU programme, four 12-month surveys have already been completed to establish baseline Salmonella levels in layer and broiler flocks, turkeys and slaughter pigs. Data is presented to the European Commission, analysed by EFSA, and the results collated by the European Commission (EC) to assess levels of specified zoonoses. The EC also proposes targets for reducing the levels in each EU-country, which aims to meet them through a National Control Programme (NCP) that includes animal feed production, primary animal production, processing and preparation of food of animal origin.

Formaldehyde kills bugs

The process of using Termin-8 involves applying aqueous formaldehyde onto the feed in a mist or atomised spray while mixing the feed components in a manner that ensures uniform production of a chemical adduct between formaldehydeand the feed. Anitox have found that formaldehyde-treated feedstuffs resist recontamination long after the formaldehydeitself has dissipated, up to 60 days or more. This bacterial resistance is correlated with the quantity and uniformity of distribution of a hydrolysable formaldehyde adduct, which can be readily recovered from the feed and measured. Themore evenly distributed this adduct is, the more resistant to recontamination the feed is. Bacterial resistance is importantbecause conventional feedstuffs are usually contaminated during transport and storage under the inadequate sanitary conditions. Feed generally becomes recontaminated during transport by passing through contaminated feed-handling equipment, such as augers, elevators, drag lines, bagging equipment and trucks. In storage, feed can become recontaminated by storage bins or by contact with dust, insects, rodents, birds and other animals. The quantity of bacteria capable of contaminating the feed may vary from less than 1 colony per gram, up to numerous colonies per gramme of feed. It is very difficult to keep the animals healthy when they are eating contaminated feed.(Source: www.patenstorm.us)

In the poultry sector, pathogen control measures have led to even higher standards in an industry that already puts tremendous effort and resources into minimising the risk of infection. For example, 95% of UK layer producers vaccinate. Additionally, breeder feeds delivered in bulk for parent/grandparent stock of all species are now heat-treated.

In many countries the presence of Salmonella still continues to cause significant economic loss. The problem is multi-factorial and with no single source of infection it challenges poultry at every stage of production. Whilst birds kept outdoors are generally thought of as being ‘healthier’, it is impossible to control the outdoor environment. Consequently, the more free-range the system, the greater the challenges.

Salmonella, Campylobacter and Listeria – the main pathogens that cause problems in humans – have all been found in feed. Even if the feed is heat-treated during pelleting, this may not be sufficient to kill all pathogens, particularly Clostridia perfringens, which can survive very high temperatures. Contamination will therefore occur unless additional measures are implemented to guarantee that the feed is free from pathogens.

Unlike heat-treatment, Anitox Termin-8^® prevents recontamination during the handling, storage and transportation phases. The US Food and Drug Administration (FDA) has approved a label claim that it does so for up to 21 days. Because the product works only in the feed, it has no residual effect in the gastrointestinal tract, leaves no residue in tissue, eggs or milk, has no withdrawal time, and does not reduce beneficial bacteria in the gastrointestinal tract.

Study feed treatment

An independent study conducted by Anderson and Richardson in 1999 investigated how the control of bacteria in feed can improve egg production and quality in laying flocks. Using Hyline W36 white layers from 17-66 weeks of age, it showed that Termin-8® produced considerable improvements. Whilst feed consumption fell from 113.7 g/day to 113.5 g/day, annual egg production rose from an average of 270.1 eggs to 274.7, and daily egg mass rose from 46.7 g to 47.8 g. The shell surface Enterobacteriaceae count declined from 11,600 CFU/egg to 1,460 CFU/egg, overall Enterobacteriaceae levels fell from 7,233 CFU/g to 42 CFU/g, and coliform levels reduced from 597 CFU/g to zero.

The relative importance of different sources of Salmonella infections in animals varies, but in regions with a low prevalence, or where endemic infection is well controlled or absent, feed is the major source for introducing it into the production chain. For precisely this reason many of the world’s major feed companies use a treatment programme to ensure that feed is pathogen-free. This is particularly important in countries with high average ambient temperatures, such as the Middle East.

More information can be obtained from Anitox at www.anitox.co.uk