Heat stress, a common stressor in commercial poultry production, negatively affects growth and intestinal function of broiler chickens. Two experiments were conducted to evaluate the effects of a Saccharomyces cerevisiae-derived yeast fermentation product on cecal microbiome and indicators of intestinal barrier function in stressed broiler chickens. Yeast fermentate (YF) was added to the feed (1.25 kg/t) or drinking water (1.60 mL/L) for the duration of each experiment. In Exp. 1, 1-D-old male broiler chickens (N = 300 birds/treatment) were assigned to 1 of 3 treatments: stressed control (CS), stressed + YF in the feed (XS), and stressed + YF in the drinking water (AS). All birds were reared on re-used litter (d 0 to 42) and spray-vaccinated for coccidiosis (d 0). On d 18, all birds were spray-vaccinated for Newcastle/Bronchitis, then exposed to a 12 h concurrent heat stress and feed and water withdrawal. Cecal microbiome did not differ in composition or diversity between or within treatments on d 42. In Exp. 2, 1-D-old male broiler chickens (N = 40 birds/treatment) were reared to 43 d of age. Treatments included CS, XS, AS, non-stressed control (CN), non-stressed + YF in the feed (XN), and non-stressed + YF in the drinking water (AN). Stressed treatments were exposed to cyclic heat stress d 28 to 43 for 12 h/d. Blood samples collected on d 42 were used to analyze plasma chemistry, interleukin(IL)-1α, IL-8, and alpha-1-acid glycoprotein (α₁-AGP); ileum samples collected on d 43 were used to assess histomorphology. Heat stress increased plasma creatine kinase (P < 0.001), uric acid (p < 0.001), sodium/potassium ratio (P < 0.001), and IL-1α (P < 0.001), but decreased alkaline phosphatase (P = 0.04), potassium (P < 0.001), IL-8 (P < 0.001), and α₁-AGP (P = 0.048). Plasma glutamate dehydrogenase was higher in birds fed the control diet or YF in the feed (P < 0.001) compared to birds supplemented with YF in the drinking water. Heat stress decreased villus height (P < 0.001) and crypt depth (P < 0.001), and increased villus/crypt ratio (P < 0.001) and goblet cell density (P < 0.001). Supplementing YF in the drinking water increased villus height (P < 0.001) and crypt depth (P = 0.036) compared to supplementing YF in the feed. Adding YF to the drinking water may be an effective method to mitigate heat-stress induced changes in villus height and crypt depth during cyclic heat stress.

热应激是商业家禽生产中常见的应激源，会对肉鸡的生长和肠道功能产生负面影响。进行了两个实验，以评估酿酒酵母衍生的酵母发酵产物对盲肠微生物组的影响以及应激肉鸡肠道屏障功能的指标。在每个实验期间，将酵母发酵液（YF）添加到饲料（1.25 kg / t）或饮用水（1.60 mL / L）中。在实验中 1，1- D型雄性肉鸡（N = 300羽鸡/处理）被分配给3种处理之一：压力控制（CS），饲料中的压力+ YF（XS）和饮用水中的压力+ YF（AS）。将所有家禽饲养在重复使用的垫料上（d 0至42），并喷雾接种球虫病（d 0）。在第18天，对所有鸡进行纽卡斯尔/支气管炎的疫苗接种，然后同时经受12小时的热应激以及饲喂和取水。盲肠微生物组在第42天的治疗之间或之内的组成或多样性没有差异。2，1- d -old雄性肉仔鸡（Ñ = 40只鸟/处理）被饲养到43天。处理包括CS，XS，AS，非压力对照（CN），饲料中的非压力+ YF（XN）和饮用水中的非压力+ YF（AN）。应力处理暴露于d 28至43的循环热应力下12 h / d。收集在d 42的血液样品用于分析等离子体化学，白细胞介素（IL）-1α，IL-8，和α-1-酸性糖蛋白（α ₁ -AGP）; 在第43天收集回肠样品用于评估组织形态。热应激会增加血浆肌酸激酶（P <0.001），尿酸（p <0.001），钠/钾比（P <0.001）和IL-1α（P <0.001），但碱性磷酸酶减少（P  = 0.04），钾（P <0.001），IL-8（P <0.001），和α ₁ -AGP（P  = 0.048）。与在饮用水中添加了YF的家禽相比，饲喂对照饮食或YF的家禽中的血浆谷氨酸脱氢酶更高（P <0.001）。热应激降低了绒毛高度（P <0.001）和隐窝深度（P <0.001），并增加了绒毛/隐窝比率（P <0.001）和杯状细胞密度（P <0.001）。在饮用水中补充YF会增加绒毛高度（P <0.001）和隐窝深度（P = 0.036），而在饲料中添加YF。在饮用水中添加YF可能是减轻热应激在周期性热应激过程中引起绒毛高度和隐窝深度变化的有效方法。