The use of reduced protein diets in broiler chicken production provides potential benefits for performance and environmental footprint of production. The effectiveness of β-Mannanase supplementation in wheat and soy based standard protein (SP) and reduced protein (RP) diets was tested for growth performance, nutrient utilisation and selected intestinal gene expression of broiler chickens. In a 2 × 2 factorial arrangement of treatments, two main factors included dietary protein (standard and reduced protein) and β-Mannanase supplementation (with or without). All diets contained phytase and carbohydrases (xylanase and glucanase). A total of 480 Ross 308 male off-sex day-old chickens were assigned to the four experimental diets in a 35-d study. Each diet was replicated 12 times with 10 birds per replicate. Using an additional 160 birds, separate apparent metabolizable energy (AME) and nutrient digestibility assays were undertaken for the 4 experimental diets from d 21 to 24 of age. Selected genes involved in gut integrity, inflammation and immune response were quantified using quantitative PCR assays. There was no interaction between β-Mannanase and dietary protein for any of the studied parameters except ileal viscosity. Enzyme had no effect on feed intake but tended to increase body weight gain (BWG) from d 0 to 35 of age (P = 0.079). Birds fed RP diet consumed more feed when assessed from d 0 to 35 of age (P = 0.029). At the same time, β-Mannanase tended to reduce feed conversion ratio independent of dietary protein (P = 0.069). β-Mannanase reduced ileal viscosity of the birds fed RP diet (P < 0.001). Reducing dietary protein increased nitrogen retention, nitrogen digestibility coefficient and digestibility coefficients of 11 amino acids (P < 0.001). β-Mannanase significantly improved digestibility coefficients of nitrogen and Arg, Gly, Thr, Lys, and Ile (P < 0.05). Dietary treatments had no effect on AME or gene expression of selected tight junction proteins, interleukin-10, interleukin-1β, mucin-2 and nuclear factor-kappa B. In conclusion, supplementation of β-Mannanase tended to improve feed efficiency and increased nutrient digestibility of broilers fed wheat-based diets independent of a moderate reduction in dietary protein. Complementary mode of actions of β-Mannanase for intestinal health requires further investigation.

中文翻译：

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饲喂标准或中度降低膳食蛋白质日粮（添加和不补充 β-甘露聚糖酶）的肉鸡的营养利用和生长性能


在肉鸡生产中使用低蛋白日粮为生产性能和环境足迹提供了潜在的好处。测试了在小麦和大豆标准蛋白 （SP） 和低蛋白 （RP） 饮食中添加 β-甘露聚糖酶的有效性，以测试肉鸡的生长性能、营养利用和选定的肠道基因表达。在 2 × 2 因子的处理安排中，两个主要因素包括膳食蛋白质 （标准蛋白和还原蛋白） 和 β-甘露聚糖酶补充剂 （有或没有）。所有日粮都含有植酸酶和碳水化合物酶（木聚糖酶和葡聚糖酶）。在一项 480 天研究中，共有 308 只雄性非性日龄鸡被分配到四种实验饮食中。每种饮食重复 12 次，每次重复 10 只鸡。使用另外 160 只鸡，对 21 至 24 岁的 4 种实验日粮进行了单独的表观代谢能量 （AME） 和营养消化率测定。使用定量 PCR 测定对参与肠道完整性、炎症和免疫反应的选定基因进行定量。除回肠粘度外，β-甘露聚糖酶和膳食蛋白质之间的任何研究参数都没有相互作用。酶对采食量没有影响，但倾向于增加从 0 到 35 岁的体重增加 （BWG） （P = 0.079）。从 d 0 到 35 日评估时，喂食 RP 饮食的家禽消耗更多的饲料 （P = 0.029）。同时，β-甘露聚糖酶倾向于降低饲料转化率，而与日粮蛋白无关 （P = 0.069）。β-甘露聚糖酶降低了饲喂 RP 日粮的鸡的回肠粘度 （P < 0.001）。减少膳食蛋白质增加了 11 个氨基酸的氮保留率、氮消化系数和消化系数 （P < 0.001）。 β-甘露聚糖酶显著提高了氮和Arg、Gly、Thr、Lys和Ile的消化系数（P < 0.05）。饮食处理对 AME 或选定的紧密连接蛋白、白细胞介素-10、白细胞介素-1β、粘蛋白-2 和核因子-κ B 的基因表达没有影响。总之，补充 β-甘露聚糖酶往往会提高饲喂小麦饮食的肉鸡的饲料效率和营养消化率，而与日粮蛋白质的适度减少无关。β-甘露聚糖酶对肠道健康的互补作用方式需要进一步研究。