Animal feed preservatives: The microbiological quality of the feed is a factor of great importance in animal production because of its impact on productivity and health status of the animals.

In addition, the importance of microorganisms (bacteria, fungi or yeasts) and toxins present in the feed also lies in the fact that they can reach human consumption and cause disease. Thus, some microorganisms are a risk for Public Health, as well as other agents causing diseases, like mycotoxicosis and toxi-infections.

The most common digestive infections in poultry can be caused by bacteria, such as Clostridium or Campylobacter; the Enterobacteria family, such as E. coli, Salmonella or Proteus; or fungi, such as Aspergillus, Candida or Mucor. There are differences between these types of microorganisms, either by location or predisposing causes of the disease. Bacteria are usually primary agents that cause high morbidity and mortality, compared to fungi, whose overgrowth is usually related to immunosuppression situations.

Prevention of digestive pathologies related to food quality

Pathogenic microorganisms can be introduced into the feed chain at different points of the production process: in raw materials, in finished feed, during production or transport, as well as through personnel, visitors, or by wild animals that can access to the facilities ( wild birds, rodents or insects).

Therefore, different measures must be taken to reduce the risk of feed contamination, such as:

• Proper design and execution of a plan of hygiene, either in feed mills and farms, including corrective measures to be applied. These plans must establish the conditions of feed manufacture, storage and transport.
• Proper design and execution of a plan of disinfection, deratization and disinfection (DDD), and corrective measures to be applied.
• Proper design and execution of a plan of management to reduce the use of antibiotics and to avoid or reduce stress situations that can lead to immunosuppression.
• Inclusion of animal feed preservatives on raw materials and feed.

Use of preservatives

There are different animal feed preservatives that can be applied to control its microbial load, such as the use of products based on organic acids, formaldehyde or the cimenol ring.

Animal feed preservatives based on organic acids usually include propionic acid and formic acid in their formulations. As the spectrum of action of one acid might be reduced, different acids must be combined in order to expand its spectrum. These acids decrease the pH of the medium and, thereby, inhibit the enzymatic metabolism of pathogenic microorganisms and their growth. This means that they have fungistatic and bacteriostatic effect, since they are not able to eliminate these microorganisms and their effect is limited in time. The use of these products may also corrode the facilities.

Formaldehyde is another type of animal feed preservative. It is a biocidal compound, very reactive and volatile. This organic compound may cause thermal burns in the digestive tract when used at high dosages and lose its effectivity in the intestine. Different publications have shown its toxicity and danger to animal and human health, as it is irritant for the skin and airways, carcinogenic and mutagenic, and it may also cause reproductive problems. Therefore, its use in animal feed is prohibited in many countries of the world.

The cimenol ring is a molecule of plant origin with a long-term bactericidal and fungicidal effect (proven efficacy up to six months) and a broad spectrum of action. animal feed preservatives based on cimenol ring have a low reactivity, and it is not corrosive or toxic.

Conclusions

The microbiological quality of the feed is a basic factor to evaluate in animal production for its economic and productive impact, as well as for the Public Health risk that it may entail.

Prevention of feed contamination by certain pathogenic microorganisms should be based on the development and application of good hygiene and management practices, that should start in the production of the raw materials and end when feed is administered in the feeders.

These practices will help to reduce the potential microbial load, but they should be complemented with the application of animal feed preservatives, commonly based on organic acids, formaldehyde or cimenol ring.

After evaluating the spectrum of action, properties and disadvantages of the different products, the use of natural solutions based on cimenol ring, as animal feed preservatives, should be highlighted, due to its long-term biocidal effectiveness, broad spectrum of action and safe application.