Petri Renee M, Pourazad Poulad, Khiaosa-Ard Ratchaneewan, Klevenhusen Fenja, Metzler-Zebeli Barbara U, Zebeli Qendrim
Institute of Animal Nutrition and Functional Plant Compounds, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
PLoS One. 2017 Aug 1;12(8):e0182271. doi: 10.1371/journal.pone.0182271. eCollection 2017.
Subacute rumen acidotic (SARA) conditions are a consequence of high grain feeding. Recent work has shown that the pattern of grain feeding can significantly impact the rumen epimural microbiota. In a continuation of these works, the objective of this study was to determine the role of grain feeding patterns on the colonization and associated changes in predicted functional properties of the fiber-adherent microbial community over a 48 h period. Eight rumen-cannulated Holstein cows were randomly assigned to interrupted or continuous 60%-grain challenge model (n = 4 per model) to induce SARA conditions. Cows in the continuous model were challenged for 4 weeks, whereas cows of interrupted model had a 1-wk break in between challenges. To determine dynamics of rumen fiber-adherent microbial community we incubated the same hay from the diet samples for 24 and 48 h in situ during the baseline (no grain fed), week 1 and 4 of the continuous grain feeding model as well as during the week 1 following the break in the interrupted model. Microbial DNA was extracted and 16SrRNA amplicon (V3-V5 region) sequencing was done with the Illumina MiSeq platform. A significant decrease (P < 0.001) in fiber-adherent rumen bacterial species richness and diversity was observed at the end of a 4 week continuous SARA challenge in comparison to the baseline. A total of 159 operational taxonominc units (OTUs) were identified from the microbial population representing > 0.1% relative abundance in the rumen, 18 of which were significantly impacted by the feeding challenge model. Correlation analysis of the significant OTUs to rumen pH as an indicator of SARA showed genus Succiniclasticum had a positive correlation to SARA conditions regardless of treatment. Predictive analysis of functional microbial properties suggested that the glyoxylate/dicarboxylate pathway was increased in response to SARA conditions, decreased between 24h to 48h of incubation, negatively correlated with propanoate metabolism and positively correlated to members of the Veillonellaceae family including Succiniclasticum spp. This may indicate an adaptive response in bacterial metabolism under SARA conditions. This research clearly indicates that changes to the colonizing fiber-adherent rumen microbial population and their predicted functional genes occur in both the short (48 h) and long term (4 wk) under both continuous and interrupted SARA challenge models.
亚急性瘤胃酸中毒（SARA）状况是高谷物喂养的结果。最近的研究表明，谷物喂养模式会显著影响瘤胃壁微生物群。在这些研究的延续中，本研究的目的是确定谷物喂养模式在48小时内对纤维附着微生物群落的定殖及预测功能特性相关变化的作用。八头装有瘤胃瘘管的荷斯坦奶牛被随机分配到间断或持续60%谷物挑战模型（每个模型n = 4）以诱导SARA状况。持续模型中的奶牛接受4周的挑战，而间断模型中的奶牛在挑战之间有1周的休息期。为了确定瘤胃纤维附着微生物群落的动态变化，我们在基线期（不喂谷物）、持续谷物喂养模型的第1周和第4周以及间断模型休息后的第1周，将来自日粮样本的相同干草原位培养24小时和48小时。提取微生物DNA，并使用Illumina MiSeq平台进行16SrRNA扩增子（V3-V5区域）测序。与基线相比，在4周持续SARA挑战结束时，观察到纤维附着瘤胃细菌物种丰富度和多样性显著下降（P < 0.001）。从瘤胃中相对丰度大于0.1%的微生物群体中总共鉴定出159个可操作分类单元（OTU），其中18个受到喂养挑战模型的显著影响。将显著的OTU与作为SARA指标的瘤胃pH进行相关性分析，结果显示无论处理如何，琥珀酸分解菌属与SARA状况呈正相关。对功能性微生物特性的预测分析表明，乙醛酸/二羧酸途径在SARA状况下增加，在培养24小时至48小时之间减少，与丙酸代谢呈负相关，与包括琥珀酸分解菌属在内的韦荣球菌科成员呈正相关。这可能表明在SARA状况下细菌代谢的适应性反应。这项研究清楚地表明，在持续和间断SARA挑战模型下，定殖于纤维附着的瘤胃微生物群体及其预测的功能基因在短期（48小时）和长期（4周）都会发生变化。
