Lactobacilli are generally accepted as beneficial microbes. Despite this, in our hands, lactobacilli do not permanently colonise chicken intestinal tract and do not protect chickens against Salmonella Enteritidis challenge. We have repeatedly shown that if lactobacilli and Salmonella meet each other for the first time as late as in the chicken crop, lactobacilli administration does not lead to protection of chickens against Salmonella. However, if lactobacilli and Salmonella are simultaneouysly inoculated to chicken feed and conditions are set so that fermentation may proceed, metabolic activity of lactobacilli leads to decrease in pH and suppression of Salmonella viability. The most common and frequent probiotic effect of lactobacilli as probiotics is therefore expressed as fermentation and decrease in pH what results in suppression of other microbiota viability including pathogens like Salmonella. For more details, see HERE.