Liu Y L, Yan T, Li X Y, Duan Y L, Yang X, Yang X J
College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi712100, China.
Animal. 2020;14(8):1619-1628. doi: 10.1017/S1751731120000191. Epub 2020 Feb 28.
The development of digestive organs and the establishment of gut microbiota in pullets play an important role throughout life. This study was conducted to investigate the effects of Bacillus subtilis (BS) on growth performance, intestinal function and gut microbiota in pullets from 0 to 6 weeks of age. Hy-line Brown laying hens (1-day-old, n = 504) were randomly allotted into four diets with a 2 × 2 factorial design: (1) basal diet group (control); (2) antibiotics group (AGP), the basal diet supplemented with 20 mg/kg Bacitracin Zinc and 4 mg/kg Colistin Sulphate; (3) BS group, the basal diet supplemented with 500 mg/kg BS and (4) mixed group, the basal diet supplemented with both AGP and BS. As a result, when BS was considered the main effect, BS addition (1) reduced the feed conversion ratio at 4 to 6 weeks (P < 0.05); (2) decreased duodenal and jejunal crypt depth at 3 weeks; (3) increased the villus height : crypt depth (V : C) ratio in the duodenum at 3 weeks and jejunal villus height at 6 weeks and (4) increased sucrase mRNA expression in the duodenum at 3 weeks as well as the jejunum at 6 weeks, and jejunal maltase and aminopeptidase expression at 3 weeks. When AGP was considered the main effect, AGP supplementation (1) increased the V : C ratio in the ileum at 3 weeks of age; (2) increased sucrase mRNA expression in the duodenum at 3 weeks as well as the ileum at 6 weeks, and increased maltase expression in the ileum. The BS × AGP interaction was observed to affect average daily feed intake at 4 to 6 weeks, and duodenal sucrase and jejunal maltase expression at 3 weeks. Furthermore, dietary BS or AGP addition improved caecal microbial diversity at 3 weeks, and a BS × AGP interaction was observed (P < 0.05) for the Shannon and Simpson indexes. At the genus level, the relative abundance of Lactobacillus was found to be higher in the mixed group at 3 weeks and in the BS group at 6 weeks. Moreover, Anaerostipes, Dehalobacterium and Oscillospira were also found to be dominant genera in pullets with dietary BS addition. In conclusion, BS could improve intestinal morphology and change digestive enzyme relative expression and caecum microbiota, thereby increasing the efficiency of nutrient utilization. Our findings suggested that BS might have more beneficial effects than AGP in the study, which would provide theoretical evidence and new insight into BS application in layer pullets.
雏鸡消化器官的发育和肠道微生物群的建立在其整个生命过程中都起着重要作用。本研究旨在探讨枯草芽孢杆菌（BS）对0至6周龄雏鸡生长性能、肠道功能和肠道微生物群的影响。海兰褐蛋鸡（1日龄，n = 504）采用2×2析因设计随机分为四种日粮：（1）基础日粮组（对照组）；（2）抗生素组（AGP），基础日粮添加20 mg/kg硫酸黏杆菌素和4 mg/kg硫酸新霉素；（3）BS组，基础日粮添加500 mg/kg BS；（4）混合组，基础日粮同时添加AGP和BS。结果表明，以BS为主要效应时，添加BS（1）降低了4至6周龄时的饲料转化率（P < 0.05）；（2）降低了3周龄时十二指肠和空肠隐窝深度；（3）提高了3周龄时十二指肠绒毛高度与隐窝深度（V:C）比值以及6周龄时空肠绒毛高度；（4）提高了3周龄时十二指肠以及6周龄时空肠蔗糖酶mRNA表达，以及3周龄时空肠麦芽糖酶和氨肽酶表达。以AGP为主要效应时，添加AGP（1）提高了3周龄时回肠的V:C比值；（2）提高了3周龄时十二指肠以及6周龄时回肠蔗糖酶mRNA表达，以及回肠麦芽糖酶表达。观察到BS×AGP互作影响4至6周龄时的平均日采食量以及3周龄时十二指肠蔗糖酶和空肠麦芽糖酶表达。此外，日粮添加BS或AGP提高了3周龄时盲肠微生物多样性，并且观察到BS×AGP互作对香农指数和辛普森指数有影响（P < 0.05）。在属水平上发现，3周龄时混合组以及6周龄时BS组中乳酸杆菌的相对丰度较高。此外，厌氧棒菌属、脱卤杆菌属和颤螺菌属也是添加日粮BS的雏鸡中的优势属。总之，BS可改善肠道形态，改变消化酶相对表达和盲肠微生物群，从而提高养分利用效率。我们的研究结果表明，在本研究中BS可能比AGP具有更多有益作用，这将为BS在蛋雏鸡中的应用提供理论依据和新的见解。
