Dietary antibiotics have been used in the food animal industry for more than 60 years, not only to control infectious diseases, but also to increase feed efficiency and improve growth performance. In chickens, subtherapeutic, in-feed antibiotics can increase body weight gain up to 8% and decrease the feed conversion ratio (feed intake/body weight gain) up to 5%, both compared with an antibiotic-free diet. Antibiotics overuse and abuse on a global scale have led to the emergence of multi-drug resistant “superbugs” from food animals and humans. The United States Food and Drug Administration has requested that agriculture producers discontinue sub-therapeutic dosing of antibiotics into animal feed, which for over 60 years, was the common practice to promote their economic value by increasing feed efficiency and growth. Therefore, development of novel antibiotic alternatives that can replace growth promoting drugs is timely and critical for sustainability of animal agriculture. At this third international symposium on alternatives to antibiotics, various strategies for developing novel alternatives to antibiotics for agriculture animal production will be discussed and we will learn more on the mode of action of novel antibiotic alternatives. In this talk, I will review our current knowledge on the underlying mechanisms of action of growth promoting drugs, the effects of antibiotics on gut microbiota and alternative alternatives to antibiotics. Antibiotics were originally thought to improve animal growth through reductions in the number and diversity of the normal bacterial flora present in the gut, which in turn, increased the bioavailability of nutrients available to the host and/or reduced the production of microbial metabolites deleterious to animal growth. Alternatively, antibiotics were suggested to improve growth performance through an antiinflammatory effect directed toward the intestinal epithelium. With the advent of novel molecular biology and bioinformatics techniques, it is now clear that changes in the host intestinal inflammatory response, as well as the structure and diversity of the gut microbial community, occur when antibiotics are introduced into animal diets. Because there is a close cross talks that influence gut microbiota, immune system and brain function, understanding these interactions is critical to develop novel antibiotic alternatives. Current technological advances in “omics” technology is enabling global gene expression and metabolomic studies in commercial food animals to obtain better understanding of biochemical processes for the development of novel compounds for alternative ways of promoting growth and immunity. These approaches should provide the framework for future studies to identify natural chemical compounds to improve poultry growth performance without the use of in-feed antibiotics.
Keywords: Antimicrobial resistance, Microbiota, Antibiotics, Alternatives to antibiotics.
Abstract presented at the 3rd International Symposium on Alternatives to Antibiotics 2019.