The overall goal of the proposed project is to assess the potential benefits of active dry yeast (ADY) supplementation on post-weaning calf health and growth performance, and to optimize a pre-conditioning management program that provides resource-limited Florida cow-calf producers with a competitive advantage in the beef supply chain. Feeding corn-based high-soluble starch diets to ruminant animals has been shown to alter the pH of the rumen, resulting in a change in their gut microbiota. The decreasing pH kills gram-negative bacteria, resulting in endotoxin or lipopolysaccharide (LPS) build up in the rumen and translocation into the bloodstream and ultimately to the liver. This LPS influx induces cytokine production such as TNFα, which causes liver damage. However, yeast supplementation has been demonstrated to stabilize rumen fermentation, nutrient digestibility and immunity in calves fed total mixed rations post-weaning. In deed yeast can competitively dislodge toxins produced by pathogenic bacteria from active binding sites in the gastrointestinal tract promoting growth performance in animals.We hypothesize that the blood profiles of calves fed a corn-based pre-conditioning diet will have higher levels of pro-inflammatory cytokines than the blood profiles of calves fed a commercially available complete diet. Further, this might instigate a subclinical inflammatory state that might be detrimental to the metabolic health of the animals resulting in suppressed performance. We further propose that ADY supplementation will reduce endotoxin flux in beef calves fed a corn-based pre-conditioning diet resulting in their improved metabolic health and growth performance and to share the information with stakeholders and explore further opportunities for improving calf health and productivity with industry partners.