Well balanced organic acid blends can protect poultry flocks from the effects of pathogenic bacteria and promote poultry growth.
Salmonella is a gram-negative, motile rod. It is non-spore forming and facultative anaerobic bacteria. To date, more than 2,500 strains of Salmonella have been identified. This bacterium infects animals either via the environment (wild birds, rodents, insects, pet animals, visitors, water) or through feed.
Different strategies have been suggested for controlling Salmonella in feed. Of these, the use of acidifiers in feed has been found to be among the most effective. Since 75-80% of production cost is involved with feeding of flocks, more attention must be paid towards effective acidification through feed than any other means.

The Acidifer action
Acidifers infeed have two modes of action. The first is a reduction of pH in the digestive tract, which takes place when acids dissociate in a liquid environment and liberate protons (H+). Inorganic acids, which dissociate completely, will have a strong effect of pH-levels.
Salmonella can live under a pH range of four to nine, but the optimum range for its growth is at 6.5 to 7.5. At these pH-levels. Salmonella requires only eight minutes to generate. In contrast, at a pH-level of 5.5, the growth rate of Salmonella is slowed to a generation time of almost 18 minutes. Therefore, low pH values in the environment inhibit the growth of the bacteria.
The key basic principle behind the mode of action is that acids, when un-dissociated (non-ionized, more lipophilic), can penetrate the bacteria cell wall and disrupt the normal physiology of bacteria.
Organic acids will pass through the bacterial cell membrane in un-dissociated form. Since the proportion of dissociated acids increases as pH rises, once inside the cell, they will be exposed to the near neutral intracellular pH of bacteria. Upon dissociation, such acids will liberate an anion (A) and a proton (H+) in the cytoplasm, reducing the internal pH. Because pH sensitive bacteria does not tolerate huge differences between internal and external pH, a specific mechanism, known as H+ - ATPase pump, will act to bring the pH inside the bacteria to normal level.
This phenomenon consumes energy and eventually stops the growth of the bacteria or even kills it. The anionic (A) part of acid is trapped inside bacteria because if diffuses freely through the cell wall only in its un-dissociate form. The accumulation of (A) becomes toxic to the bacteria by complex mechanisms and inhibits metabolic reactions. At the same time, this also reduces synthesis of macro molecules and disrupts membranes.
Typically blends of organic acids representing different stages of dissociation and undissociation, like formic and propionic acid are more effective against Salmonella than single acids alone. This synergistic effect has been demonstrated by observing the effect of combination of propionic and formic acids and comparing that with single acids.
Well balanced acidifier required the right combination of dissociated and un-dissociated organic acids (choosing organic acids, like formic and propionic acids, with different pKa values – the pH at which the acid is 50% dissociated – so at same pH, for example in the small intestine, dissociated and un-dissociated acids are present. The behavior gives advantage of having organic acids which can reduce the pH (need to be dissociated) and organic acids that have a direct antimicrobial effect (need to be un-dissociated) present simultaneously.
Biomin’s acidifier line, Biotronic SE is a combination of formic and propionic acids as well as their corresponding salts. A carrier chosen to enable a sequential release of the acids ensures a long lasting product with beneficial effects in the stomach and intestine. Because of this, Biotronic is classified as non-hazardous and non-corrosive.
A trial was conducted to show the effect of Briotronic on Salmonella typhimurium in intestinal juices. Feed samples were mixed with the intestinal juice, and inoculated with 10 cube cells of Salmonella at an incubation temperature of 37 degree centigrade.
After 0 and 4 hours, samples from both timings were taken and the number of colony forming units determined, results found that gram negative bacteria Salmonella typhimurium was reduced in small intestine.

Summary
The efficacy of organic acids against Salmonella depends on their concentration and degree of dissociation. Combining different organic acids have synergistic effects. Special attention should also be focused on using a carrier that ensures liberation of these acids at their site of action and avoid problem of corrosion. Biomin’s integrated approaches to animal nutrition concepts help consumers unlock the real potential of their bird flocks.

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