The population increase in the last century was the first cause of the industrialization of animal productions, together with the necessity to satisfy the high food demand and the lack of space and land for the husbandry practices. As a consequence, the farmers moved from extensive to intensive agricultural systems and introduced new practices, such as the administration of antimicrobial drugs. Antibiotics were then used as growth promoters and for disease prevention. The uncontrolled and continuous use of antibiotics contributed to the spread of antibiotic resistance in animals, and this had adverse impacts on human health. This emergence led the European Union, in 2003, to ban the marketing and use of antibiotics as growth promoters, and for prophylaxis purposes from January 2006. This ban caused problems in farms, due to the decrease in animal performances (weight gain, feed conversion ratio, reproduction, etc.), and the rise in the incidence of certain diseases, such as those induced by Clostridium perfringens, Salmonella, Escherichia coli, and Listeria monocytogenes. The economic losses due to the ban increased the interest in researching alternative strategies for the prophylaxis of infectious diseases and for health and growth promotion, such as feed additives. Yeast-based materials, such as cell wall extract, represent promising alternatives to antibiotics, on the base of their prebiotic activity and their claimed capacity to bind enteropathogenic bacteria. Several authors reported examples of the effectiveness of yeast cell wall products in adsorbing bacteria, but there is a lack of knowledge on the mechanisms involved in this interaction. The purpose of this review is to provide an overview of the current approaches used for the control of pathogenic bacteria in feed, with a particular focus on the use of yeast-derived materials proposed to control zoonoses at farm level, and on their effect on animal health.
Keywords: antibiotics; biosecurity; eubiotics; feed; growth promoters; yeast cell wall.