Roles of Probiotics in Farm Animals: A Review

Abstract

There are many reports of the positive effects of probiotics on gastrointestinal tract (GIT) microorganisms and the immunological systems of their hosts. Probiotics have prophylactic and metaphylactic properties. The two main mechanisms of action of probiotics seem to be the release of compounds with beneficial effects and direct interaction with the cells of the host. The aim of this review was to evaluate the benefits of probiotic use in farm animals and to identify how they influence farm animal performance. The published data suggest that dietary supplementation of probiotics can improve the growth performance, nutrient digestibility, and immune response of farm animals, including cows, sheep, goats, pigs, aquacultures, and poultry. In ruminants, studies have shown that probiotics can significantly enhance the immune response, milk yield, food digestibility, and weight gain, particularly in ruminants exposed to stressful conditions. This is also the case in aquaculture as probiotics have been shown to enhance growth and reproduction traits, provide protection against pathogens, have positive effects on immunity, optimize digestion, and increase water quality. In horses, there is still controversy about the advantages of probiotic supplementation. In addition, some studies showed valuable effects of using probiotics on treatments of GIT diseases, and some studies showed adverse effects of supplementation of probiotics in horses. In poultry, balancing the intestinal microflora is not achievable but controlling the population of microflora is possible and studies showed that supplementation of probiotics could influence some aspects such as improving performance and health parameters. So, probiotics are used by almost all farmers who are trying to reduce antibiotic resistance. In conclusion, dietary supplementation of probiotics to farm animals has many notable influences on their performance, immune system, and diet digestion.