We evaluated the effects of supplementing direct-fed microbials (DFM), containing Bacillus licheniformis and Bacillus subtilis, on performance, rumen morphometrics, intestinal gene expression, and blood and fecal parameters in finishing bulls. Nellore × Angus bulls (n = 144; initial BW = 401 ± 45.5 kg) were distributed at random in 36 pens (4 bulls/pen and 18 pens/treatment), following a completely randomized design. A ground corn-based finishing diet was offered for ad libitum intake twice a day for 84 d, containing the following treatments: 1) control (without DFM); 2) DFM (B. licheniformis and B. subtilis) at 6.4 × 109 CFU (2 g) per animal. The data were analyzed using the MIXED procedure of SAS, with a pen representing an experimental unit, the fixed effect of the treatment, and the random effect of pen nested within the treatment. For fecal parameters (two collections made), the collection effect and its interaction with the treatment were included in the model. Bulls that received the DFM had a decreased dry matter intake (P ≤ 0.01), did not differ in average daily gain (2.05 kg; P = 0.39), and had a 6% improvement in gain:feed (P = 0.05). The other performance variables, final BW, hot carcass weight, and hot carcass yield, did not differ (P > 0.10). Plasma urea-N concentration decreased by 6.2% (P = 0.02) in the bulls that received DFM. Glucose, haptoglobin, and lipopolysaccharides were not different between treatments (P > 0.10). Ruminal morphometrics were not affected by the treatment (P > 0.10). The use of DFM tended to reduce fecal starch (P = 0.10). At slaughter, bulls fed DFM had an increased duodenal gene expression of tryptophan hydroxylase-1 (P = 0.02) and of superoxide dismutase-1 (P = 0.03). Overall, supplementation with DFM based on B. licheniformis and B. subtilis to Nellore × Angus bulls in the finishing phase decreased dry matter intake, did not influence ADG, improved gain:feed, and increased the expression of genes important for duodenal function.

中文翻译：

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基于芽孢杆菌的直接饲喂微生物对育肥肉牛生产性能、血液参数、粪便特性、瘤胃形态学和肠道基因表达的影响


我们评估了补充含有地衣芽孢杆菌和枯草芽孢杆菌的直接饲养微生物 （DFM） 对育肥公牛生产性能、瘤胃形态学、肠道基因表达以及血液和粪便参数的影响。Nellore × 安格斯公牛 （n = 144;初始体重 = 401 ± 45.5 kg） 随机分布在 36 个围栏 （4 头公牛/围栏和 18 个围栏/处理） 中，遵循完全随机设计。提供以磨碎玉米为基础的育肥饲料，每天两次自由摄入，持续 84 天，包括以下处理：1） 对照（无 DFM）;2） 每只动物 6.4 × 109 CFU （2 g） 的 DFM（地衣芽孢杆菌和枯草芽孢杆菌）。使用 SAS 的 MIXED 程序分析数据，其中笔代表实验单位、治疗的固定效果以及嵌套在治疗中的笔的随机效果。对于粪便参数 （制作了两个集合），收集效应及其与治疗的相互作用包含在模型中。接受 DFM 的公牛干物质摄入量减少 （P ≤ 0.01），平均日增重没有差异 （2.05 kg;P = 0.39），并且增重：饲料提高了 6% （P = 0.05）。其他性能变量，最终体重、热胴体重量和热胴体产量没有差异 （P > 0.10）。接受 DFM 的公牛血浆尿素-N 浓度下降了 6.2% （P = 0.02）。葡萄糖、结合珠蛋白和脂多糖在处理间无差异 （P > 0.10）。瘤胃形态测量学不受处理的影响 （P > 0.10）。使用 DFM 倾向于减少粪便淀粉 （P = 0.10）。在屠宰时，饲喂 DFM 的公牛的色氨酸羟化酶-1 （P = 0.02） 和超氧化物歧化酶-1 （P = 0.03） 的十二指肠基因表达增加。总体而言，补充基于 B 的 DFM。 在育肥阶段，Nellore × Angus 公牛的 licheniformis 和 B. subtilis 减少了干物质摄入量，不影响 ADG，提高了增重：饲料，并增加了对十二指肠功能很重要的基因的表达。