The Role of Direct-Fed Microbials in Conventional Livestock Production.

Supplementation of direct-fed microbials (DFM) as a means to improve the health and performance of livestock has generated significant interest over the past 15+ years. A driving force for this increased interest in DFM is to reduce or eliminate the use of low-dose antibiotics in livestock production. This increased attention toward DFM supplementation has generated an extensive body of research. This effort has resulted in conflicting reports. Although there has been considerable variation in the design of these studies, one of the main causes for this lack of consistency may be attributed to the variation in the experimental immune challenge incorporated to evaluate DFM supplementation. Taking into account the experimental immune challenge, there is strong evidence to suggest that DFM supplementation may have an impact on the immune response, overall health, and performance of livestock.