February 2014 – Another word on feed additives

Further to my musings last month, where I discussed the additives that can save you money by direct replacement, I want to mention another group of additives that are already standard issue, but must be clearly flagged up because of their growing importance: the organic acids.

We continue to march towards a period where antibiotic medication has less and less effect, owing to microbial resistance. As Dr Margaret Chan of the WHO states “a post-antibiotic era means, in effect, an end to modern medicine as we know it. Things as common as tonsillitis or a child’s scratched knee could once again kill”. These are chilling words, but realistic if we ignore the issue.

Danish influence in the EU is pushing to radically review the use and administration of antibiotics on farms. This will force each production system in Europe to examine its biosecurity and management protocols.

This is a good thing for many reasons. It’s known that the biggest economic influence on pig production is disease, and reducing pathogenic pressure, in whichever way we can, will improve performance and margins. A trial at the University of Adelaide revealed a 50g/day difference in grower/finisher performance when comparing a cleaned all-in/all-out system with a continuous-flow system.

There are a number of non-medicinal routes we can use to support a medication free (or as best as) production system. One of these is the centuries-old use of organic acids. Their original use was as a preservative in foods, such as pickles, but they were also used to control pathogens like E coli, Salmonella, Clostridia, Listeria and Campylobacter in products like ham and sausages.

The most typical organic acids used in animal feed include lactic acid, proprionic acid, formic acid, benzoic acid and butyric acid. Each has its own particular speciality. Formic and lactic acid are very effective killers of bacteria, but proprionic acid is good for killing yeasts and moulds. But how do they work?

It all comes down to chemistry: the definition of organic chemistry is the presence of carbon atoms, whereas inorganic chemistry is without carbon. The definition of an acid is the ability to donate a positive hydrogen ion into an environment by a process known as dissociation and its strength is based on the number of hydrogen atoms being donated.

An organic acid will, by passive diffusion, enter a bacterial cell where it dissociates into a positively charged hydrogen component, known as the cation and the negatively charged rest-group known as the anion. Both the cation and anion will affect the bacterial cell. First, the cation will kill the bacteria as the cell actively has to excrete the damaging positively charged particles, costing a vast amount of energy. The rest-group anion binds with the genetic material of the bacteria, stopping it from reproducing.

There are a number of well-researched blends of acids for use in feed, or in water, and it’s comforting to know that research has not yet discovered any form of pathogenic resistance to treatment with organic acids.

> Dr Phil Baynes has spent his career in pig welfare and nutrition. Now based in Cheshire, he runs Baynes Nutrition and is a consultant nutritionist to Provimi

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