Effects of different stocking densities on tracheal barrier function and its metabolic changes in finishing broilers

Abstract In the present study, we evaluated the effects of various stocking densities on the tracheal barrier and plasma metabolic profiles of finishing broilers. We randomly assigned 1,440 Lingnan Yellow feathered broilers (age 22 d) to five different stocking density groups (8 m-2, 10 m-2, 12 m-2, 14 m-2, and 16 m-2). Each of these consisted of three replicates. The IL-1β and IL-10 concentrations were substantially higher in the 16 m-2 treatment group than they were in the 8 m-2 and 10 m-2 treatment groups (P 0.05). The tracheal mucosae of the birds in the 16 m-2 group (high stocking density, HSD) were considerably thicker than those for the birds in the 10 m-2 group (control, CSD). Relative to CSD, the claudin1 expression level was lower and the muc2 and caspase3 expression levels were higher for HSD. Compared with CSD, 10 metabolites were significantly upregulated (P