Effects of dietary saponin and polyphenol supplementation in broiler chickens exposed to multiple mild stressors of cyclic elevated ambient temperature, feed withdrawal, and coccidiosis infection

Broilers are commonly exposed to numerous environmental and immunological stressors in a production setting. In this study, two botanical feed additives were evaluated for their effects on growth performance, antioxidant defenses, and intestinal health in stressed broilers. To achieve a multiple mild stressors challenge, birds underwent a 12-h feed withdrawal prior to a coccidiosis vaccine challenge on d 15 of the study, which was designated as 0 d post-inoculation (DPI). Additionally, birds were exposed to cyclic elevated ambient brooder temperatures during the grower phase. A total of 420 male Ross 708 chicks at 2 d post-hatch were assigned to 1 of 5 treatment groups with 7 birds allotted to each of 12 replicate cages. The 42-d study (starter d 0-14, grower d 14-28, finisher d 28-42) was conducted with treatments including: 1) control diet + birds not exposed to stressors (NC), 2) control diet + birds exposed to stressors (PC), 3) PC + 500 mg of Micro-Shield/kg of diet in the starter phase only (MS), 4) PC + 500 mg of Micro-Shield/kg diet in the starter, grower, and finisher phases (MSall), and 5) PC + 500 mg of Micro-Shield/kg diet in the starter phase + 250 mg of Micro-Aid/kg diet in the grower and finisher phases (MS+MA). All data were subjected to a 1-way ANOVA using the MIXED procedure of SAS with results considered significant when P < 0.05. Birds exposed to stressors had impaired growth performance during the grower phase compared with birds in the NC group (P < 0.05). On 6 DPI, birds in the MS+MA treatment had the highest (P < 0.05) levels of catalase in blood serum, potentially indicating higher antioxidant capacity. While birds in the NC treatment had the highest gene expression of zonula occludens-1 (ZO-1) in jejunal mucosa tissue on 6 DPI (P < 0.05), MS+MA birds had similar ZO-1 expression compared with NC birds. These results suggest botanicals may confer health benefits in broilers experiencing environmental and immunological stressors.