本试验旨在探讨和揭示甘露聚糖酶对豆粕日粮引发的肉鸡肠道炎症的影响及作用机制。在这个实验中,将384只1d龄的Arbor英亩肉鸡随机分为3个处理组。饲喂玉米豆粕基础日粮的肉鸡,低能量饮食(代谢能减少50千卡/公斤),和补充100mg/kg甘露聚糖酶的低能量日粮42d。低能量日粮使饲料转化率从0增加到42d,回肠绒毛高度和绒毛高度与隐窝深度之比降低,并上调回肠核因子κB(NF-κB)的表达(P<0.05)。它还减少盲肠短链脂肪酸(SCFA),如乙酸(P<0.05)。与低能量饮食相比,添加甘露聚糖酶在42d时增加了体重,促进了营养物质的消化率,保持了肉仔鸡肠上皮的形态和完整性(P<0.05)。此外,甘露聚糖酶在21d时上调空肠claudin-1(CLDN1)和小带闭塞1(ZO-1)的表达,下调回肠NF-κB的表达,提高了肉鸡盲肠中异丁酸的含量(P<0.05)。回肠微生物群的结果表明,低能量饮食导致肉鸡回肠中罗伊氏乳杆菌的相对丰度降低。甘露聚糖酶的添加增加了肉鸡中KC45b乳杆菌和约氏乳杆菌的相对丰度。此外,低能量日粮会降低肉鸡肠道中丁霉素的相对丰度,并抑制氧化磷酸化和磷酸肌醇代谢。甘露聚糖酶增加了Odoribacter的相对丰度,促进能量代谢和N-聚糖生物合成,并增加了GH3和GH18的活动。结论甘露聚糖酶可以通过降低回肠NF-κB的表达来提高肉鸡的生长性能,增加盲肠中SCFA的产量,抑制肠道炎症,平衡肠道微生物群,减少对肠道屏障的损害,提高营养利用效率,减轻膳食能量水平下降带来的不利影响。
This experiment aimed to discuss and reveal the effect and mechanism of
mannanase on intestinal inflammation in broilers triggered by a soybean meal diet. In this experiment, 384 Arbor Acres broilers at 1 d old were randomly divided into 3 treatment groups. The broilers were fed a corn-soybean meal basal diet, a low-energy diet (metabolizable energy reduced by 50 kcal/kg), and a low-energy diet supplemented with 100 mg/kg
mannanase for 42 d. The low-energy diet increased feed conversion ratio from 0 to 42 d, reduced ileal villus height and villus height-to-crypt depth ratio and upregulated the expression of nuclear factor kappa B (NF-κB) in the ileum (P < 0.05). It also reduced cecal short-chain fatty acids (SCFA), such as acetic acid (P < 0.05). Compared with low-energy diets, the addition of
mannanase increased body weight at 42 d, promoted the digestibility of nutrients, and maintained the morphology and integrity of the intestinal epithelium of broilers (P < 0.05). In addition,
mannanase upregulated the expression of claudin-1 (CLDN1) and zonula occludens-1 (ZO-1) in the jejunum at 21 d, downregulated the expression of ileal NF-κB, and increased the content of isobutyric acid in the cecum of broilers (P < 0.05). The results for the ileal microbiota showed that a low-energy diet led to a decrease in the relative abundance of Lactobacillus reuteri in the ileum of broilers. The addition of mannanase increased the relative abundance of Lactobacillus-KC45b and Lactobacillus johnsonii in broilers. Furthermore, a low-energy diet reduced the relative abundance of Butyricicoccus in the intestine of broilers and inhibited oxidative phosphorylation and phosphoinositol metabolism. Mannanase increased the relative abundance of Odoribacter, promoted energy metabolism and N-glycan biosynthesis, and increased the activities of GH3 and GH18. It is concluded that
mannanase could improve the growth performance of broilers by reducing the expression of NF-κB in the ileum, increasing the production of SCFA in the cecum, suppressing intestinal inflammation, balancing the intestinal microbiota, reducing damage to the intestinal barrier, and improving the efficiency of nutrient utilization to alleviate the adverse effects caused by the decrease in dietary energy level.