Purpose: We conducted a series of experiments to test whether phage therapy could be used to counteract Salmonella infections at this critical pre-processing period. Methods: Fourteen anti-Salmonella phage were isolated from wastewater treatment facilities and characterized by electron microscopy. In preliminary experiments, microencapsulated phage were co-administered with Salmonella enterica Typhimurium to 4 to 5 week-old pigs (n = 8 per group). In the main experiment designed to mimic a production setting, microencapsulated phage were administered to market weight pigs (n = 8 per group in three replicates) prior to their comingling with Salmonella enterica Typhimurium infected pigs in a contaminated pen. Results: Treating the small pigs with the phage cocktail at the time of inoculation with Salmonella enterica Typhimurium reduced the extent of Salmonella colonization by 99.0 to 99.9% (2 to 3 log growth) in the tonsils, ileum, and cecum as compared to mock-treated pigs. Under the production-like setting, treatment of market weight pigs with the antiSalmonella phage cocktail significantly reduced cecal Salmonella counts (95%, P 6.3 log CFU/cm2 turkey breast after 28 days of refrigerated storage, while EC strains showed > 2.0 log CFU/cm2 variation in final populations (ranging from 4.4 to 6.6 log CFU/cm2) at 28-d post-inoculation. Intracellular growth assays revealed that EC strains grew to higher levels by 9 h (P = 0.0018), but by 12 h no significant differences existed between the two groups Technical 56 — Abstract Book