Direct-fed microbials may hold promise as an alternative to growth promoting additions of antibiotics added to swine diets. A study conducted at the University of Arkansas evaluated the effects of two direct-fed microbials (Lactobacillus brevis and a Bacillus culture) on growth, gastrointestinal microflora, and immune system characteristics of weanling pigs compared to antibiotic supplementation with Carbodox (generic name?). Both supplementation with Lactobacillus brevis and the antibiotic resulted in improved average daily gain, feed intake, and body weight at the end of the trial compared to pigs fed a basal diet. In addition, Lactobacillus brevis supplementation altered the gastrointestinal microbial population. Different bacterial populations were present in pigs provided Lactobacillus brevis that were absent in pigs not administered 1E1, and similarly, populations were present in pigs not provided Lactobacillus brevis that were absent in pigs exposed to Lactobacillus brevis. Furthermore, the combination of Lactobacillus brevis and Bacillus seems to result in beneficial immune responses characteristic of decreased inflammation similar to antibiotic supplementation.