Nutrient availability is critical for the development of poultry digestive function and immune responses. Carbohydrase formulations, containing α-galactosidase (CAG) enzyme with specificity for galacto-oligosaccharides from soybean meal (SBM), have been shown to increase dietary ME in monogastric diets. This exploratory study aimed at evaluating the effect of CAG on the growth performance and humoral immunity of broilers fed corn–SBM diets with varying energy density. A total of 640 male 1-day-old chicks were allocated at random to one of 64 floor pens, with 10 birds each. Replicates were assigned to a 4 × 2 factorial experimental design. Four dietary energy density levels were formulated, namely control and with a −70, −100, and −120 kcal/kg of feed ME downspecification to the control. Each of these diets was treated with 2 levels of CAG supplementation, either none (−) or at a dose of 200 g/tonne (+). Growth performance was determined over a 35-D period. At the end of the study, carcass processing parameters, organ weight, and dimensions of the intestine were determined in 1 randomly selected bird per replicate. Humoral immunity was measured by quantification of antibody titers to Newcastle disease vaccination, in 1 bird per replicate, at 21 and 35 d of age. Dietary ME had a significant effect on BW and feed conversion ratio (FCR) (P < 0.05). Regression analysis confirmed differences in the linear response of CAG groups (− or +) in terms of elevation (P < 0.05) for BW gain and FCR. Significant interaction of the main effects confirmed that CAG maintained carcass dressing percentage equivalent to the control diet (P < 0.05). CAG increased antibody titers of broilers at 35 d, irrespective of the dietary energy density (P < 0.001). In conclusion, the impact on broiler growth performance from feeding low-energy-density diets can be ameliorated with a CAG enzyme.

营养物质的供应对于家禽消化功能和免疫反应的发展至关重要。含α-半乳糖苷酶（CAG）酶对豆粕（SBM）中的半乳寡糖具有特异性的糖酶制剂已显示可增加单胃饮食中的饮食代谢。这项探索性研究旨在评估CAG对以不同能量密度饲喂玉米-SBM日粮的肉鸡的生长性能和体液免疫的影响。将总共​​640只1天大的雄性小鸡随机分配到64只落地笔中的一只，每只10只。将副本分配给4×2阶乘实验设计。制定了四个饮食能量密度水平，即对照和饲料ME的下限-70，-100和-120 kcal / kg。这些饮食中的每一种都用2种水平的CAG补充剂进行了处理，无添加（-）或剂量为200克/吨（+）。在35天内确定生长性能。在研究结束时，每重复1只随机选择的家禽，确定car体加工参数，器官重量和肠道尺寸。通过定量针对新城疫疫苗接种的抗体效价来测量体液免疫力，每只禽类在21和35 d时重复一次。日粮ME对BW和饲料转化率（FCR）有显着影响（通过定量针对新城疫疫苗接种的抗体效价来测量体液免疫力，每只禽类在21和35 d时重复一次。日粮ME对BW和饲料转化率（FCR）有显着影响（通过定量针对新城疫疫苗接种的抗体效价来测量体液免疫力，每只禽类在21和35 d时重复一次。日粮ME对BW和饲料转化率（FCR）有显着影响（P <0.05）。回归分析证实了BW增益和FCR的CAG组（-或+）线性响应的差异（P <0.05）。主要作用的显着相互作用证实，CAG维持car体敷料的百分率与对照饮食相当（P <0.05）。与日粮能量密度无关，CAG在35 d时可提高肉鸡的抗体滴度（P <0.001）。总之，饲喂低能量密度日粮对肉鸡生长性能的影响可以用CAG酶改善。