Expt. 1 evaluated effects of 0 or 10 ppm CAP in the starter phase (d 1-16) on chicks challenged with SE on d of age. Therapeutic inclusion of 10ppm CAP increased (P < 0.05) L/S and ceca positives. In Expt. 2, capsaicin oleoresin (CO) was included in finisher diets (d 30-37) at 0, 5, or 20 ppm with SE challenge on day 31. Inclusion of 5 ppm CO increased (P < 0.05) ceca SE positives and demonstrated 1.05 and 1.39-log fewer SE cfu at CO concentration of 5 or 20 ppm, respectively. A linear decrease (P < 0.05) in lamina propria thickness of SE challenged birds was observed with increased CO. Expt. 3 evaluated prophylactic CO treatment at 0, 5, or 20 ppm in starter, grower, and finisher diets for resistance to SE or ST challenge on d 14 or 29. With challenge on d 14, 5 ppm CO reduced ceca (P<0.005) SE positives and 1.1-log fewer SE cfu. Likewise, 20 ppm CO reduced (P < 0.05) SE ceca positives. Salmonella typhimurium isolation rate was reduced (P<0.05) with 5 ppm CO, and ST cfu were reduced 1.4-log with 5 ppm CO compared to 20 ppm. Lamina propria thickness increased (P < 0.05) linearly as CO concentration increased. With d 29 challenge birds fed 5 ppm CO exhibited 1.08-log fewer SE cfu, and 20 ppm CO reduced L/S positives (P < 0.025) for SE and resulted in 1.39-log fewer SE cfu. Lamina propria thickness decreased with 5 ppm CO and SE or ST challenge compared to non-challenged birds fed 5 ppm (P < 0.0005). An increase was observed in ST or SE, birds fed 20 ppm CO compared to non-challenged, birds fed 20 ppm CO (P < 0.01). No differences were observed in mast cell number in either Expt. 2 or 3.

These data provide evidence that prophylactic or therapeutic dietary CAP differentially affect broiler susceptibility to Salmonella and prophylactic administration may provide non-antibiotic means to reduce Salmonella in broilers.