Evaluating the Effects of Feeding a Concentrated Saccharomyces cerevisiae Fermentation Product on the Performance and Stress Susceptibility of Broiler Chickens

This study evaluated the effect of a concentrated yeast fermentation product on the performance and stress response of broiler chickens. Day-old Cobb 500 male broiler chicks were randomly allocated to one of two dietary treatments: Control (CON) or concentrated yeast fermentation product (CSCFP, 0.625 kg/MT). On d18, simultaneous feed withdrawal and heat stress challenges were performed for 12 h. Blood was analyzed for plasma corticosterone (CORT) and heterophil-to-lymphocyte ratio (HL) on d19 and d42. Performance parameters were collected throughout the trial: body weight (BW), feed consumption (FC), and feed conversion ratio (FCR). On d19, the CSCFP birds had lower (p <= 0.05) CORT (5320.3 ng/mL) and HL (0.14) than the CON birds (9049.6 ng/mL and 0.21). On d42, the CSCFP birds had lower (p <= 0.05) CORT (1623.8 ng/mL) and HL (0.74) than the CON birds (2920.2 ng/mL and 1.05). No differences were observed in mortality (p > 0.05). The CON birds had a higher (p <= 0.05) FCR than CSCFP throughout all phases. The CON birds consumed more feed than the CSCFP birds throughout all phases (p <= 0.05). In conclusion, CYFP reduced stress and improved feed conversion when compared to CON, making it a viable feed additive to improve welfare and production.