Summary of the Pork Industry Conference on Antibiotic Use in Animal Agriculture

May 9, 2006 — Butch Baker

The University of Illinois, Department of Animal Science and the National Pork Board sponsored a conference on April 27-28 entitled "Pork Industry Conference on Antibiotic Use in Animal Agriculture". Dr. Butch Baker attended the conference and offered the following summary of the information presented.

Several members of the AASV spoke at this conference and others were in attendance. The conference addressed four broad topics associated with the use of antimicrobials in animal agriculture - resistance, microbe enhancement of gut integrity, health management with reduced antibiotic use, and current research on alternative products.

The opening sessions concerned the fundamentals of antibiotic resistance. It was a lively session with activists making their presence known during the discussion periods. The basic mechanisms of resistance development and transmission amongst bacterial populations (commensals, pathogens, and free living) were presented and discussed. Bacteria often develop resistance by mutation and selection when exposed to antimicrobials but this alone would not be cause for concern. Many resistance factors are naturally dispersed in nature and bacteria have evolved numerous strategies for acquiring this genetic information from their environment. Many times these packets of genetic information contain multi-resistance codes which exponentially magnifies the problem.

It was not doubted by those present that antimicrobial resistant bacteria are becoming a major and increasing threat to human and animal health. Once acquired by populations of bacteria resistance information may persist for many decades after antimicrobials are removed. This is highly variable depending on the antimicrobial class and other dynamics of nature. Many bacteria have pre-stored (transposons) genetic factors of resistance which can be "shuffled" into action in time of need.

The risk to public health by the use of agriculture antimicrobials was discussed at length. The question of whether resistance factors are passed from animals to resident human gut bacteria through food was thoroughly considered. This process is an important issue with growing data supporting the presumption that direct and indirect resistance transfer rates between food animals and humans are high. There is also growing evidence that antimicrobials used in companion animal medicine may play a more significant role in the transfer of resistance from animal to human bacteria than animal protein consumption. It was the consensus that removing antimicrobials from animal agriculture may have little or no impact on public health and overall resistance issues. Several talks were given on how antimicrobials used at "subtherapeutic" levels promote improved productivity. This appears to be a function of reduced numbers and kinds of microbes present in the gut and by reducing immune response level. Studies on the numerous alternatives to antimicrobials were presented. Unfortunately none of these look very promising with a few exceptions (zinc, copper) which are already used by the pork industry.

The last part of the conference dealt with managing pigs with reduced antibiotic use. The Scandinavian and Danish experiences were presented. Their ban on subtherapeutic use has significantly reduced the annual tonnage of antimicrobials given to pigs. The unintended consequence has been a greater level of disease and treatment usage (and so far no improvement in human health). This has been especially true in nursery pigs. The EU mandated increase in weaning age has helped post weaning issues but further reduced farm productivity. The importance of health maximization, biosecurity, disease elimination, and other management factors were presented. The cost of producing Antibiotic Free Pigs (ABF) was discussed. Few cuts of meat end up as value added products and along with added production costs this type of production is limited to niche markers and high health status systems. Non-traditional replacements to antimicrobials were presented. Some products appear to have viable special situation applications but overall the impact of these products is currently limited. Repeatedly the message was that antimicrobial use in animal agriculture is essential for the preservation of welfare and sustainable productivity.

The Take Care - Use Antibiotics Responsibly? program developed by the National Pork Board in collaboration with many industry and consumer stakeholders was presented. This program is based on responsible use protecting animal and human health, and maintaining US pork industry competitiveness.

The manuscripts from this conference will be published in one complete monthly issue of Animal Biotechnology (a peer-reviewed, refereed journal) late 2006 or early 2007.

[Ed. AASV e-Letter thanks Dr. Baker for providing this summary.]

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Dr. Butch Baker, NCSU CVM, Population Health and Pathobiology