Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis 95616; Department of Animal Sciences, University of Florida, Gainesville 32611.
Department of Animal Sciences, University of Florida, Gainesville 32611; Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista Júlio de Mesquita Filho, Botucatu, Brazil, 18618-681.
J Dairy Sci. 2022 Mar;105(3):2242-2255. doi: 10.3168/jds.2021-21025. Epub 2022 Jan 5.
The objective of this study was to evaluate ruminal microbiome changes associated with feeding Lactobacillus plantarum GB-LP1 as direct-fed microbials (DFM) in high-producing dairy cow diets. A dual-flow continuous culture system was used in a replicated 4 × 4 Latin square design. A basal diet was formulated to meet the requirements of a cow producing 45 kg of milk per day (16% crude protein and 28% starch). There were 4 experimental treatments: the basal diet without any DFM (CTRL); a mixture of Lactobacillus acidophilus, 1 × 10 cfu/g, and Propionibacterium freudenreichii, 2 × 10 cfu/g [MLP = 0.01% of diet dry matter (DM)]; and 2 different levels of L. plantarum, 1.35 × 10 cfu/g (L1 = 0.05% and L2 = 0.10% of diet DM). Bacterial samples were collected from the fluid and particulate effluents before feeding and at 2, 4, 6, and 8 h after feeding; a composite of all time points was made for each fermentor within their respective fractionations. Bacterial community composition was analyzed through sequencing the V4 region of the 16S rRNA gene using the Illumina MiSeq platform. Sequenced data were analyzed on DADA2, and statistical analyses were performed in R (RStudio 3.0.1, https://www.r-project.org/) and SAS 9.4 (SAS Institute Inc.); orthogonal contrasts were used to compare treatments. Different than in other fermentation scenarios (e.g., silage or beef cattle high-grain diets), treatments did not affect pH or lactic acid concentration. Effects were mainly from overall DFM inclusion, and they were mostly observed in the fluid phase. The relative abundance of the phylum Firmicutes, family Lachnospiraceae, and 6 genera decreased with DFM inclusion, with emphasis on Butyrivibrio_2, Saccharofermentans, and Ruminococcus_1 that are fibrolytic and may display peptidase activity during fermentation. Lachnospiraceae_AC2044_group and Lachnospiraceae_XPB1014_group also decreased in the fluid phase, and their relative abundances were positively correlated with NH-N daily outflow from the fermentors. Specific effects of MLP and L. plantarum were mostly in specific bacteria associated with proteolytic and fibrolytic functions in the rumen. These findings help to explain why, in the previous results from this study, DFM inclusion decreased NH-N concentration without altering pH and lactic acid concentration.
本研究旨在评估在高产奶牛日粮中作为直接添加微生物（DFM）添加植物乳杆菌 GB-LP1 后瘤胃微生物组的变化。采用重复 4×4 拉丁方设计的双流通连续培养系统。基础日粮的配方满足日产 45 公斤奶的奶牛的需求（粗蛋白 16%，淀粉 28%）。有 4 个实验处理：不添加任何 DFM 的基础日粮（CTRL）；嗜酸乳杆菌和丙酸纤维菌混合物，1×10cfu/g，2×10cfu/g[MLP=日粮干物质（DM）的 0.01%]；和 2 种不同水平的植物乳杆菌，1.35×10cfu/g（L1=日粮 DM 的 0.05%，L2=0.10%）。在进料前和进料后 2、4、6 和 8 小时从液体和颗粒流出物中采集细菌样品；为每个发酵罐在各自的馏分中制作所有时间点的组合。通过使用 Illumina MiSeq 平台对 16S rRNA 基因的 V4 区域进行测序来分析细菌群落组成。对测序数据进行 DADA2 分析，并在 R（RStudio 3.0.1，https://www.r-project.org/）和 SAS 9.4（SAS Institute Inc.）中进行统计分析；使用正交对比比较处理。与其他发酵情况（例如青贮或肉牛高谷物日粮）不同，处理方式并未影响 pH 值或乳酸浓度。影响主要来自于整体 DFM 的添加，主要发生在液体相中。厚壁菌门、lachnospiraceae 科和 6 个属的相对丰度随着 DFM 的添加而降低，其中重点是丁酸弧菌_2、Saccharofermentans 和 Ruminococcus_1，它们是纤维分解菌，在发酵过程中可能具有肽酶活性。lachnospiraceae_AC2044_group 和 Lachnospiraceae_XPB1014_group 在液体相中也减少，它们的相对丰度与从发酵罐中每天流出的 NH-N 呈正相关。MLP 和植物乳杆菌的特定影响主要在与瘤胃中蛋白水解和纤维分解功能相关的特定细菌中。这些发现有助于解释为什么在本研究的先前结果中，DFM 的添加降低了 NH-N 浓度，而没有改变 pH 值和乳酸浓度。
