Animal Health Research Reviews

Review Article

Probiotics, prebiotics and competitive exclusion for prophylaxis against bacterial disease

T. R. Callawaya1 c1, T. S. Edringtona1, R. C. Andersona1, R. B. Harveya1, K. J. Genovesea1, C. N. Kennedya2, D. W. Venna3 and D. J. Nisbeta1

a1 Food and Feed Safety Research Unit, Southern Plains Agricultural Research Center, Agricultural Research Service, USDA, College Station, TX 77845, USA

a2 Kennedy and Associates Research, Colorado Springs, CO, USA

a3 Department of Biology, Georgia State University, Atlanta, GA, USA


The microbial population of the intestinal tract is a complex natural resource that can be utilized in an effort to reduce the impact of pathogenic bacteria that affect animal production and efficiency, as well as the safety of food products. Strategies have been devised to reduce the populations of food-borne pathogenic bacteria in animals at the on-farm stage. Many of these techniques rely on harnessing the natural competitive nature of bacteria to eliminate pathogens that negatively impact animal production or food safety. Thus feed products that are classified as probiotics, prebiotics and competitive exclusion cultures have been utilized as pathogen reduction strategies in food animals with varying degrees of success. The efficacy of these products is often due to specific microbial ecological factors that alter the competitive pressures experienced by the microbial population of the gut. A few products have been shown to be effective under field conditions and many have shown indications of effectiveness under experimental conditions and as a result probiotic products are widely used in all animal species and nearly all production systems. This review explores the ecology behind the efficacy of these products against pathogens found in food animals, including those that enter the food chain and impact human consumers.

(Received August 28 2008)

(Accepted October 03 2008)


c1 Corresponding author: E-mail:


Mandatory Disclaimer: ‘Proprietary or brand names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product, and/or exclusion of others that may be suitable.’