Technical Abstract: Bacteria that are pathogenic to animals and human consumers can exist in the gastrointestinal tract of our food animal species. The gastrointestinal tract of food animals can be inhabited by bacteria that cause foodborne illnesses in humans, but that do not cause detectable animal illnesses or a decrease in production efficiency. The microbial population of the intestinal tract is a complex natural resource that can be utilized in an effort to reduce 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 foodborne 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. In this review, we will explore 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.