FEED Business Worldwide - July 2012

 

Do acidifiers help in controlling Salmonella and other bacteria? 

 

by Nataliya ROTH

 

 

Food safety is one of the top priorities in animal production today. Salmonella is a cause of bacterial food-borne disease in humans, and can often be attributed to contaminated food products. It is estimated that around 2.6%, 10.6%, 17.0% and 56.8% of human salmonellosis cases can be attributed to turkeys, broilers, laying hens and pigs, respectively. On-farm Salmonella control is an important issue which is directly linked to slaughterhouse regulations and a public health concern. Effective Salmonella control on the farm is based on the prevention of Salmonella entering and spreading in a farm.

 

Salmonella spp. is one of the major hazards for the microbial contamination of animal feed. In addition, antimicrobial resistant bacteria, or antimicrobial resistance genes can be transmitted via feed. Animal-derived protein and oilseed meals are the major sources of risk among feed materials, through which Salmonella may be introduced to industrial compound feed and feed mills.

 

International regulations require that food and feed are free from Salmonella. Appropriate process control and decontamination steps are needed during feed processing to reduce the contamination of feedstuffs and avoid the dissemination of contaminated feed to livestock herds. It has been demonstrated in experimental settings that animals can become infected by consuming Salmonella contaminated feed, which can be further carried over to products of animal origin.

 

It is important to check all raw materials, especially cereals and protein sources, for Salmonella contamination. In general, Salmonella counts in feed are low. It is important to know that Salmonella colonies are naturally unevenly distributed in feed. Therefore, detection and quantification of Salmonella can be difficult. Consequently, preventing the spread of Salmonella is a recommended tool for Salmonella control.

 

The heat treatment of feed is a common means of feed sanitation. However, it should be conducted appropriately in order to reduce bacteria counts, taking into account, in particular, temperature, treatment duration and initial bacterial counts. Moreover, heat treatment does not protect feed from recontamination during transportation and storage.

 

A multiple strategy encompassing heat and antimicrobial treatments, for instance, with organic acids, is required for the reduction of bacterial burden and improvement of feed hygiene. Acid treatments have a residual protective effect on feed, which reduces both recontamination risk and also the contamination of milling equipment, feeding equipment and the general environment. The efficacy of organic acids against Salmonella depends on the level of bacterial contamination.

 

 

 

The addition of organic acids has been shown to contribute to environmental hygiene by preserving feed raw materials and compound feed from microbial and fungal deterioration. Moreover, by interrupting bacterial transmission in the animal-to-food chain, acidifiers contribute to good farm management. The supplementation of organic acids in compound feed tends to decrease feed pH, buffer capacity and prevent the growth of undesirable microbes.

 

Organic acids inhibit bacterial growth through the interference of bacterial metabolism. They decrease cytoplasmatic pH while inhibiting enzymatic action and DNA synthesis. The mode of action of organic acids on infectious, pathogenic micro-organisms has been well documented by many researchers. It has been also determined that a blend of formic acid and propionic acids included in the feed can prevent cecal colonization of newly-hatched chicks by Salmonella enterica serovars Typhimurium, Enteritidis, Agona and Infantis (Iba and Berchieri, 1995).