Immuno-Modulation and Anti-Inflammatory Effects of Antibiotic Growth Promoters Versus Probiotics in the Intestinal Tract

Antibiotics as growth promoters (AGP) in the feed of different animal species have been used for many years to improve feed efficiency and growth. The mechanisms of how antibiotics can promote growth are not well known; nevertheless several studies have focused on interactions between antibiotics and intestinal microflora. However, many scientists have suggested that there may be other modes of action of some antibiotics, including the capacity of these antibiotics to produce immunomodulatory and antiinflammatory effects. It has been demonstrated that antibiotics are able to inhibit one or more functions of inflammatory cells and pro-inflammatory cytokine production. Consequently, AGP may prevent immunologic stress that is associated with metabolic changes, allowing more energy to be available for muscle development thus, improving growth. Although the use of AGP in animal production has advantages, its extensive use has been suggested to have contributed to the emergence of antimicrobial resistance in zoonotic pathogens, resulting in a ban by the European Union with suggestive restrictions by other countries. The withdrawal of AGP from livestock production has led to an increase in cost, a decrease in production, and an increase in disease incidence, forcing food animal producers to find alternatives including probiotics, which have been used to enhance intestinal health. The major functional effect of probiotics may be the balance of both gastrointestinal microflora and immune-stimulation, particularly by maintaining the equilibrium of pro-inflammatory and antiinflammatory cytokines. This review describes the immuno-modulation and anti-inflammatory effects of antibiotic growth promoters versus probiotics in the intestinal tract.