Abstract: To evaluate the effect of a litter acidifier (PGLA) on Salmonella enteritidis(SE) horizontal transmission, two experiments were conducted with broiler chicks grown on used (Exp. 1) and new (Exp. 2) litter. In each experiment, three hundred day-old broiler chicks from a commercial hatchery were obtained and divided into three litter treatments with four replicate pens each. The treatments were: control (no litter treatment); low dose of PGLA (LD: 815g/2.27m2); and high dose (HD: 1631 g/2.27m2). In Exp. 1, two hundred-forty chicks were placed in floor pens with pine shaving-based litter previously used for at least two prior growouts (20 chicks/pen). Another 60 chicks were challenged with 7.5×103 cfu of SE (seeders), placed in a separate pen with clean new pine shaving-based litter for 24 hours, then 5 seeders (20%) were placed with the contact chicks in each respective treatment pen. Salmonella recovery from cecal tonsils of 10 chicks/ pen were evaluated on days 11 and 21. Application of PGLA at both LD and HD on used litter significantly reduced (p<0.05) SE recovery compared to controls (Control: 28%, LL: 0%; HL: 3% respectively) on day 11 after placement, but no difference was observed at day 21. However, a significant increase (p<0.05) in body weight was detected in the HD compared to the control group on d21, but not d11. Similarly, application of PGLA to clean pine shavings (Exp. 2) reduced (p<0.05) SE recovery from cecae of chicks cultured on day 11 (control: 46%; LD: 23%; HD: 18% respectively). Body weights through 21 days were unaffected by PGLA treatment of new litter. These data suggest that PGLA treatment of new or used litter may reduce early horizontal transmission of Salmonella. Enhanced 21-day performance of chicks on used litter treated with PGLA may suggest that other low-level pathogens were reduced by treatment, although further studies are necessary to confirm and extend these findings.