Effect of encapsulated Cosmos caudatus leaf extract on the physiological conditions, immune competency, and antioxidative status of broilers at high stocking density

The present study aimed to investigate the effect of encapsulated Cosmos caudatus leaf extract on the physiological conditions, immune competency, and antioxidative status of broiler chickens raised at a high stocking density. After 15 days of rearing, 370 Lohmann broiler chicks were assigned to five treatment groups, including T0 (chicks were raised at a density of 10 birds/m2 and received no additive), T1 (chicks were raised at a density of 16 birds/m2 and received no additive), T2 (chicks were raised at a density of 16 birds/m2 and received 0.5 g/kg encapsulated C. caudatus leaf extract), T3 (chicks were raised at a density of 16 birds/m2 and received 1.0 g/kg additive), and T4 (chicks were raised at a density of 16 birds/m2 and received 1.5 g/kg additive). On days 28 and 42, blood samples from two chicks per pen were collected. On day 42, the chicks that had been blood-sampled were sacrificed, and blood samples and lymphoid organs (i.e., bursa of Fabricius, spleen, and thymus) were collected. The daily weight gain and feed efficiency of broilers (PC. caudatus leaf extract, especially at a rate of 1.5 g/kg, could alleviate the cortical and lymphocyte cell depletion of broilers. Regardless of the stocking density effect, dietary supplementation with encapsulated C. caudatus leaf extract at doses of 0.5 and 1.0 g/kg could improve the daily weight gain of broilers.