Role of Growth Promotants in Poultry and Swine Feed

Feed producers are faced with choosing from a myriad of growth promoting substances all claimed to improve performance and have some advantage over competitive products. In most cases, these products are "nonnutritional" and contain nothing that contributes directly toward meeting the animals requirement for nutrients. Yet, many have been confirmed to be highly cost-effective when added to feeds. The selection of a growth promotant must be based on safety and probability to give high economic returns. The most widely used are the antimicrobial agents, including antibiotics. In recent years, there has been a flurry of interest in the use of other non-nutritive substances such as acidifiers,probiotics, enzymes, herbal products, beta-agonists, microflora enhancers and immunomodulators. New entries into the market are common each year, as are new research reports on products and product combinations. The purpose of this paper is to present an overview on the use and mode of action of various growth promoting substances, give some perspectives that may assist in product selection based on safety and farm conditions, and discuss future directions.