Managing Salmonella contamination: gold standard for improving feed hygiene

Foodborne diseases & global scenario:

Up to 30% of the inhabitants in developed countries may be affected by food-borne illness each year and the problems are likely to be even more serious in developing countries. The global occurrence of food-borne disease is difficult to evaluate, but in 2005 it was projected that 22 lakhs people, including 18 lakhs children, died from diarrheal diseases(WHO,2015). Microbiological hazards represent 93% of the incidents of food-borne illness and are the major problems not only in developing countries but also in developed countries.

Salmonella is a foremost cause of foodborne disease in humans worldwide and is a significant cause of morbidity and even mortality and accordingly high economic losses (Foley and Lynne, 2008). Every year almost 1 in 10 people fall ill and 33 million healthy life years are lost. CDC estimates enterobacteria causes about twelve lakhs sicknesses, 23,000 hospitalizations, and 450 deaths within America each year. Hoffmann et al (2013) stated that the total economic burden of $3.7 billion, was the impact of foodborne Salmonella in the United States in the year 2013. Conferring to David Byrne, EU Commissioner for Health and Consumer Protection, the costs of food-borne Salmonella alone are estimated to reach up to € 2.8 billion annually in EU countries altogether (European Commission, 2003).

Even though many foods are contaminated with Salmonella, raw meats, poultry, eggs, milk, and dairy products are often concerned as sources of infection (Jones, 2011). For this reason, consumers are increasingly concerned about Salmonella contaminations in their food sample. Barring Salmonella gallinarum (S. gallinarum) and Salmonella pullorum (S. pullorum) there are several serotypes of Salmonella which infect both humans and poultry and can produce infections in consumers by entering through the food chain.

There are many sources of Salmonella contamination in animals, including feed and feed ingredients such as seeds and cereal grains (Sanchez et al., 2002). Managing the contamination over feed is paramount to reduce the occurrences in animals and subsequently in humans.

Prevalence of Salmonella contamination in feed and feed ingredients:

Apart from vertical transmission, one of the possible routes of entry of Salmonella infection in animal health is feed and feed ingredients. It is noticeable to get other Enterobacteriaceae like E. coli along with Salmonella in feed and ingredients. Salmonella contamination has been allied with a higher indicator organism such as Enterobacteriaceae counts (Jones, 2011).

Strategies to minimize Salmonella contamination & transmission through feed:

Feed has been stated as a “major medium of transmission” for Salmonella into commercial farms. It is confirmed in numerous studies that when feed quality management systems based on HACCP (Hazard Analysis and Critical Control Point), GMP (Good Manufacturing Practice) and Good Hygiene Practices, were applied across all feed mills in the survey, incidences of Salmonella occurrence in poultry farms are considerably reduced. Good manufacturing practices include operational measures which are meant at producing feed that is safe and of reliable quality. A key component of feed safety is to produce the feed that is microbiologically safe and is produced on a premise where the feed hygiene management system is in place. Salmonella control program is to produce feed that is free of all Salmonellae. Hazard analysis and critical control point determination is needed to systematically identify, analyze and control. Four essential elements of a Salmonella control programme have been defined as;

1. Stringent policies of raw material purchase

2. Strict supply chain

3. Manufacturing facility sanitation and cleaning

4. Good manufacturing practices

1. Stringent policies of raw material purchase:

It is well known that Salmonellae can enter the feed milling system from raw feed ingredients and with insects being the major mode through which bacteria spreads. To some extent conditioning during pellet feed manufacturing, Salmonella is killed. While in mash feed probabilities of transmission through feed is very common. Feed ingredient supplier management systems including monitoring of ingredients for Total Enterobacteriaceae Counts (TEC) and Salmonella count are required.

Supplier's assessment in terms of inspection of storage area, checking and inspection of raw materials, signing off the approved ingredient requirement, even the examination of the vehicles for hygiene and disinfection are the portion of the feed ingredient supplier management system. Besides, the process of supply would be certified as per GMP and HACCP system

2. Strict supply chain

Throughout the supply chain activity, stringent testing are of paramount importance. At the receiving point, verify the documents and compare with approved quality management parameters is necessary. Microbiological parameters particularly Total Enterobacteriaceae Counts (TEC) and Salmonella counts are important. Additionally, raw material trucks should be examined and hygiene is of utmost need. The complete rodent and wild bird control program is of utmost requirement to exclude this source of contamination of feed ingredients. Moreover, there should be built-in excellence checkpoints for chemical quality and nutritional values.

3. Manufacturing facility sanitation and cleaning

This step is very significant when feed is mostly in mash form as there is no heat kill step. This requires complete and effective mill hygiene events to keep each point along the milling process dry and clean with minimal dust accumulation.

Managing Salmonella contamination: gold standard for improving feed hygiene - Image 2

Inside and outside of the factory shed, there must be a good water drainage capacity. There should be no water logging and roofs, ceilings and walls would not allow water ingression. Maintenance of mill cleanliness must be a part of the mill's GMP programme. Whereas regular cleaning procedures should be planned, physical cleaning should be a normal component of daily work functions, e.g. feed or feed ingredient spills must be cleaned up instantly to endorse a good 'cleaning culture'.

Dust has been proved to be the greatest source for contamination for Salmonella and Enterobacteriaceae ( Jones and Richardson, 2004). Therefore, it is very significant to control dust in feed mills from the very beginning of the feed production, i.e. from the acceptance point where the largest quantity of dust is produced (Morita et al., 2006). Grinders, mixers, conveyors, pellet scalpers, elevator legs, are additional points of dust development that must be measured within the feed mills (McDaniel, 2005). Proper air circulation system, dust controlling cyclone, equipment cleaning and hygiene audit are to be the regular practice in feed plants.

Manufacturing waste, stored unused fat and scrapped raw materials in manufacturing plants are the breeding ground of bacteria and fungi. There is the necessity to assess the potential risk and are to be disposed properly. Complete ventilation and regular pest control are to be carried out. Pests like mealworms are the potential source of transmission of Salmonella infections.

4. Moisture control and feed sanitation:

In the final feed, moisture should not be less or more than 11.5 to 12%. This is the optimum moisture percentage for better nutritional value and hygienic feed manufacturing. Higher moisture content invites growth of microbes and subsequently, quality is deteriorated. Low moisture content may cause shrinkage of feed and factory yield and subsequently performance of the animals are impacted.

Moisture optimization is now an established concept in feed manufacturing. Along with moisture control, using blends of organic acid in feed can improve the feed hygiene confirming check on transmission of pathogens like Salmonella spp and other enterobacteriaceae. Moreover, entry of Salmonella in the food chain could be checked resulting in production of safe food by improving feed hygiene.

Conclusion:

Food borne disease could be prevented by implementation of strict good manufacturing practice.

As per FAMI-QS code implementation and managing feed safety management system is quintessential to reduce transmission of diseases in livestock and subsequently incidences of foodborne disease in human beings.