Temporal effects of a botanical feed additive and experimental housing methods in broilers exposed to an acute feed withdrawal period prior to coccidiosis inoculation

In this study, a commercial feed additive [Micro-Shield™ (MS); DPI Global, Porterville, CA] and experimental housing methods were evaluated for their temporal effects on endogenous antioxidants, growth performance, and intestinal health in broilers. The 30-d study (starter d 0-14, grower d 14-30) was conducted in a 2 × 4 factorial arrangement with factors including 1) housing method [2 levels; battery cages (BC) with raised-wire flooring or floor pens (FP) with fresh pine shavings] and 2) dietary treatment [4 levels; 1) control diet fed to birds not exposed to stressors (NC), 2) control diet fed to birds exposed to stressors (PC), 3) PC + 1,000 mg of MS/kg diet in the starter phase + 500 mg of MS/kg diet in the grower phase (MSL), and 4) 1,000 mg of MS/kg diet in the starter and grower phases (MSH)]. A total of 720 male Ross 708 chicks were assigned to 1 of 8 treatment groups: BCNC, BC-PC, BC-MSL, BC-MSH, FP-NC, FP-PC, FP-MSL, or FP-MSH. Treatment groups raised in BC or FP were allotted to 10 or 8 replicates, respectively, each housing 10 birds. A multiple mild stressors challenge was imposed by birds undergoing a 12-h feed withdrawal prior to a coccidiosis vaccine challenge on study d 15, which was designated as 0 d post-inoculation (DPI). All data were analyzed by a 2-way ANOVA using SAS and effects were considered significant when P < 0.05. During the grower phase, the FP-NC treatment had the highest (P < 0.05) BWG compared with all other treatments. On 6 DPI, jejunal gene expression of IFN-γ, IL-1β, and IL-10 was highest (P < 0.05) in FP-MSH birds compared with all other treatments. On 9 DPI, there was a main effect of dietary treatment where the MSH treatment had higher (P < 0.05) serum catalase levels compared with its counterparts. These results suggest that MS supplementation, experimental housing method, and their interaction influence growth performance and overall health outcomes in experimental settings.