Animal : an international journal of animal bioscience
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Dysbiosis or dysbacteriosis is defined as a shift in the intestinal microbiota composition resulting in an imbalance between beneficial and harmful bacteria. Since the ban on the use of growth-promoting antibiotics in animal feed in the EU, dysbiosis has emerged as a major problem in intensive animal production. Prebiotics and probiotics are currently under investigation as possible alternatives to growth-promoting antibiotics, as their mode of action is thought to be based largely on a modulation of the composition and function of the intestinal microbiota. ⋯ An impressive number of empirical feeding trials have been carried out in healthy animals, yielding sometimes contradictory results. More in-depth studies have revealed the complexity of the interactions taking place in the lower intestinal tract, thus illustrating that pre- and probiotics cannot be a simple replacement for growth-promoting antibiotics. Although there are indications that the strategic use of pre- and probiotics can provide major benefits, there is still a lack of basic knowledge on the delicate interactions between the microbiota, the host and the feed components, which hampers the widespread use of these valuable feed additives.