Omics techniques said to reveal antibiotic alternatives that work

The search for alternatives, said Theo Niewold, professor at KU Leuven, has been hampered by misconceptions about the exact physiological mechanisms behind growth promotion by AGPs

Hitherto, they were attributed to their antibiotic properties.

But Niewold said the theory that the beneficial effects of AGPs were linked to their antibiotic character, was not backed by either conclusive evidence or plausible mechanism.

His hypothesis had been that growth and health in livestock is reciprocal to intestinal inflammation, so it was, thus, logical that the observed effects are rather based on an anti-inflammatory mechanism.

This hypothesis has now been confirmed, he told us. “We have been able to demonstrate that, in pigs, oxytetracycline (OTC), for example, promoted growth while inflammatory parameters in the serum proteome were down (Soler et al, 2016).”​

Niewold said the findings imply that alternatives to antimicrobial growth promoters should be non-antibiotic anti-inflammatory compounds, which also removes the fear for inducing bacterial resistance.

Biomarker developments ​

Typically, biomarkers for intestinal health have been obtained by invasive means, from blood or at slaughter, but getting them in a minimally invasive or non-invasive way such as from feces would be easier and less costly.

“Fecal myeloperoxidase (MPO) is used in humans, and we have used it successfully in pigs too,”​ said the researcher.

He said though MPO is not present in chicken. “Perhaps neopterin is a more likely candidate for use as a biomarker in poultry, we are currently testing the potential of it and others in that respect,”​ added Niewold.

Benefits of butyrate​

Niewold and colleagues have spent the past months testing fecal samples from pigs, which have been submitted by industry, to determine which additives fed to those animals were the most effective in terms of promoting growth.

Butyrate is one of the compounds that proved to be particularly effective:

“We have tested a wide range of compounds for anti-inflammatory response.  Butyrate was one of the additives that stood out. The encapsulated form promoted growth in pigs in vivo with a simultaneous lower level of fecal inflammatory biomarkers,”​ said Niewold.

The professor and his colleagues use the Raw 264.7 macrophage like cell line, which he said enables fast prescreening of larger amounts of extracts and chemical compounds, in comparison with a known anti-inflammatory compound like OTC.

He said the selected anti-inflammatory compounds were then tested in vivo​ on the university farm.

Niewold said effective anti-inflammatory compounds should show growth promotion combined with a down regulation of inflammatory parameters such as the fecal indicators or serum acute phase proteins, or lower expression of inflammatory parameters in the intestines.

Professor Niewold is presenting during the gut health and performance session of the 2016 World Nutrition Forum in Vancouver, Canada on 12-15 October. ​