DSM study: Benzoic acid controls E. coli growth in pigs
Recent trials by animal health and nutrition company DSM have confirmed that benzoic acid has a strong effect on the reduction of E. coli in pigs.
An in vitro study was carried out in order to evaluate the efficacy of different organic acids on the reduction of E. coli growth. The graphs of Figure 1 show the growth curves of E. coli colonies where the black line indicates the natural growth curve without adding any acid.
All other curves indicate the relative growth while adding always equivalent dosages of specific organic acids. The data show that benzoic acid (VevoVitall) has a strong effect on reducing E. coli to a level of 10% remaining growth and it performs better than most of the other organic acids.
Figure 1. Growth curves of E. coli colonies in an in vitro study.
Animal research trial
Next to the in vitro study, in its animal research centre, the company researched whether this effect can as well be seen in live animals. For that reason, the caecal chymus from ileo-rectal anastomosed piglets was analysed for different bacteria groups. Compared to a negative control piglets fed a diet containing 0.5% of the benzoic acid product had a significantly lower content of E. coli which confirms the effect shown in the lab study.
Figure 2. Effects of benzoic acid on E. coli in caecal chymus from ileo-rectal anastomosed piglets.
Based on theses studies it can be concluded that the benzoic acid product is one of the stronger organic acids to reduce E. coli and that this effect lasts throughout the whole intestine.
Effects on piglet performance were also tested. In several studies on weaned piglets the benzoic acid product was compared to a range of other organic acid products (acid salts, acid blends, etc.) used in piglet feeding. The average of nine comparative studies resulted in 6.1% higher daily weight gain and 2.3% lower feed conversion ratio in the piglets fed the benzoic acid product, at a 0.5% dosage.
Figure 3. Summary of studies to the effect of feeding benzoic acid to piglets on weight gain improvement and feed conversion improvement.
Controlling piglets’ intestinal microflora through feed additives is key to succesful piglet feeding. When too much feed is not digested in the small intestine, conditions become perfect for potentially pathogenic micro-organisms like E. coli to grow – this, in turn, ultimately leads to severe diarrhoea.
The role of organic acids has grown over the last ten years, especially after the ban of all antibiotic growth promoters in the European Union. Antimicrobial effects of organic acids result from a direct acidification in the stomach and a direct effect when un-dissociated acid molecules enter the microbial cells and down-regulate their organic functions. (by Dr Matthias Wiemann and Dr Christophe Paulus, DSM Nutritional Products)
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