In two trials, researchers studied the intestinal effects of providing PrimaLac Direct-Fed Microbial in a standard diet for broiler chicks, compared with the standard diet control and the diet with added salinomycin antibiotic. Gastrointestinal characteristics—pertaining to microvilli, intervilli spaces, and muscle thickness—in the DFM treated chicks, demonstrate an altered physiology that works to prevent the attachment of pathogens to the track lining.