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: BC-NC, 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.
Froebel et al. (Wed,) studied this question.