Probiotics are an alternative to increase broiler productivity and flock health. For this reason, the objective of the first study was to evaluate commercially available Bacillus spp. based probiotic products on their ability to reduce Salmonella Heidelberg, in vitro. Results showed that most products reduced the lower concentrations of S. Heidelberg and maintained a reduction for up to 8 h. The second study was conducted to determine if bacterial colonization occurred in a broiler chick after in ovo injection. Using bioluminescence, it was demonstrated that bacteria could migrate and colonize the embryo within 2 h after in ovo injection into the amniotic fluid. The results of these studies demonstrated that probiotics could reduce pathogenic microorganisms and can potentially have a positive impact on the chick before it even hatches and is placed in a broiler house.