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item Laegreid, William

Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Review Article
Publication Acceptance Date: 6/1/2004
Publication Date: 6/20/2004
Citation: Laegreid, W.W., Bauer, N. Probiotics for pathogen control in poultry and livestock. 2004. American Meat Science Association Conference Reciprocal Proceedings.

Interpretive Summary:

Technical Abstract: Enteric viruses and bacteria are a major cause of death, disease and poor performance in food-producing animals. Furthermore, the major food-borne human pathogens commonly associated with meat products are essentially all enteric organisms. Control of enteric pathogens in food-producing animals is essential both for improvement of animal health and productivity as well as to increase the safety of products for human consumption. Vaccination and/or antibiotics have been used effectively for control of enteric pathogens in food animals. However, concerns about antibiotic residues in meat products and increasing development of antibiotic resistance in pathogenic bacteria have stimulated interest in alternatives to mass therapy with antibiotics for pathogen control in food animals. A number of options have been explored as alternatives to antibiotics including dietary manipulations, chlorates and other small molecules, organic acids, bacteriophages, antimicrobial peptides and the subject of this discussion, probiotics. A commonly used definition of probiotics is provided by Fuller who states probiotics are 'live microbial feed supplements which beneficially affect the host animal by improving its intestinal microbial balance.' Reported beneficial effects include increased feed intake, feed efficiency, average daily gain, improved carcass characteristics, and decreased morbidity. Note that the above definition of probiotics makes no claim about pathogen reduction, a distinction that may have significant regulatory implications. Furthermore, confusion is introduced by various synonymous, partially synonymous and homophonic terms, such as direct fed microbials (DFM), competitive exclusion (CE) cultures, prebiotics and synbiotics. While the term DFM has been proposed by both the FDA and the American Association of Feed Control Officials for feed products based on live microbial organisms and is certainly accurate, the more generic probiotic is in common usage in both the human and veterinary literature and will be used in this paper as defined above. CE cultures are derived from indigenous intestinal microflora of healthy animals, either as undefined mixtures or characterized as to the microbial organisms present. CE cultures represent an important subset of probiotics, distinct from single microorganism probiotics. Prebiotics are 'nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon.' The term synbiotic is used to describe the combined application of pre- and probiotics to achieve a beneficial effect. The purpose of this paper is to examine the selection, possible modes of action and potential problems with probiotics for pathogen control, and to present some select examples of how probiotics have been applied towards control of specific pathogens in food animals.