Reducing Stress Susceptibility of Broiler Chickens by Supplementing a Yeast Fermentation Product in the Feed or Drinking Water

SIMPLE SUMMARY: Poultry are susceptible to stress induced as a response to common management practices such as vaccination, feed withdrawal, and rearing on reused litter as well as severe stressors such as high environmental temperature. These stressors can result in economic costs to producers that are associated with poor growth and disease. Functional metabolites in the yeast fermentation product Original XPC(TM) have previously shown positive effects on growth performance and immune function in a variety of livestock when incorporated into the diet. This study found that including either Original XPC(TM) in the feed or its liquid counterpart, AviCare(TM), in the drinking water during the entire rearing period can reduce stress and improve the welfare of broiler chickens under many stressful situations. ABSTRACT: Reducing stress is an important goal in animal production. Previous research has demonstrated the ability of Original XPC(TM) to reduce the stress response of broilers during heat stress. Three trials were conducted to evaluate the effects of adding Original XPC(TM) to the feed or AviCare(TM) to the water on stress susceptibility of broiler chickens. Treatments included: control nonstressed (CNS), control stressed (CS), stressed with Original XPC(TM) (1.25 kg/metric ton feed, 0–42 days; XPC), and stressed with AviCare(TM) (160 mL/100 L drinking water, 0–42 days; AVI). All stressed treatments received the following stressors: live coccidiosis vaccination (day 1), reared on reused litter (days 0–42), and heat stress with feed/water withdrawal (12 h on day 18). Plasma corticosterone and heterophil/lymphocyte (H/L) ratio were determined from 60 birds/T on day 19, and 24 birds/T on day 41. Physical asymmetry was determined using bilateral bone measurements from 60 birds/T on day 41. Birds provided XPC or AVI had lower corticosterone and H/L ratios than CS (p < 0.05) on day 19 and lower corticosterone, H/L ratios, and asymmetry scores than both CNS and CS on day 41 (p < 0.05) in all three trials. Supplementing XPC or AVI improved broiler welfare measured by reduced stress indicators after acute heat stress or normal rearing stress in all trials.