Viquez-Umana F L, Erickson M G, Young J D, Zanton G I, Wattiaux M A, Suen G, Mantovani H C
Department of Animal and Dairy Science, University of Wisconsin - Madison, Madison, WI, United States.
USDA-ARS, U. S. Dairy Forage Research Center, Madison, WI, United States.
Front Microbiol. 2025 Jun 10;16:1568112. doi: 10.3389/fmicb.2025.1568112. eCollection 2025.
Understanding how the rumen microbiota responds to varying protein levels and feeding patterns is critical for optimizing dairy cattle nutrition. This study investigated the influence of dietary crude protein (CP) levels (13.8% or 15.5% CP of ration dry matter) and CP feeding patterns (constant over time (static) or oscillating by 1.8 percentage units above and below the mean every 48 h) on the composition, diversity, and function of the rumen microbiome.
Using a replicated Latin Square design, eight rumen-cannulated Holstein cows were assigned each of the four dietary treatments (structured as a 2 × 2 factorial) in four consecutive 28-day periods (with 24 days of adaptation and 4 days of sampling). Rumen samples were collected 4 h post-feeding, and amplicon libraries of the V4 region of the 16S rRNA gene were sequenced and analyzed to assess changes in microbiome composition. Additionally, volatile fatty acids (VFAs) were measured to evaluate rumen microbial function.
Results indicated that dietary CP level did not alter microbial diversity ( = 0.30), but oscillating diets increased rumen microbial diversity (Shannon index, = 0.04). The rumen microbiome richness was also affected by CP feeding pattern ( = 0.05), but not dietary CP level ( = 0.27). Furthermore, differential abundance analysis using ANCOM-BC identified CAG- 352 ( = 0.0001) and an unclassified member of the family Acholeplasmataceae ( = 0.0002) as taxa significantly impacted by protein level and feeding pattern, even though their relative abundance was low (below 0.02%). The functional profile of the rumen bacterial communities was not affected by CP level or feeding pattern, and VFA profiles also remained consistent across treatments, with no observable changes in concentration.
These findings support the hypothesis that the rumen microbiome remains stable despite variations in the ruminal supply of dietary CP, suggesting that compensatory mechanisms may be involved. Although oscillating dietary CP concentration might alter the rumen microbiome, further research into rumen metabolic processes and host-microbiome interactions is needed to evaluate if the changes observed in our study are biologically relevant for developing new opportunities to enhance protein nutrition in dairy cattle.
了解瘤胃微生物群如何应对不同的蛋白质水平和饲养模式对于优化奶牛营养至关重要。本研究调查了日粮粗蛋白（CP）水平（日粮干物质的13.8%或15.5% CP）和CP饲养模式（随时间恒定（静态）或每48小时在平均值上下波动1.8个百分点）对瘤胃微生物组的组成、多样性和功能的影响。
采用重复拉丁方设计，在四个连续的28天周期（24天适应期和4天采样期）内，将八头装有瘤胃瘘管的荷斯坦奶牛分配到四种日粮处理中的每一种（构建为2×2析因设计）。在喂食后4小时采集瘤胃样本，并对16S rRNA基因V4区域的扩增子文库进行测序和分析，以评估微生物组组成的变化。此外，测量挥发性脂肪酸（VFA）以评估瘤胃微生物功能。
结果表明，日粮CP水平未改变微生物多样性（=0.30），但波动日粮增加了瘤胃微生物多样性（香农指数，=0.04）。瘤胃微生物组丰富度也受CP饲养模式影响（=0.05），但不受日粮CP水平影响（=0.27）。此外，使用ANCOM-BC进行的差异丰度分析确定，CAG-352（=0.0001）和无胆甾原体科的一个未分类成员（=0.0002）是受蛋白质水平和饲养模式显著影响的分类群，尽管它们的相对丰度较低（低于0.02%）。瘤胃细菌群落的功能概况不受CP水平或饲养模式的影响，VFA概况在各处理之间也保持一致，浓度没有明显变化。
这些发现支持了这样一种假设，即尽管日粮CP在瘤胃中的供应存在变化，但瘤胃微生物组仍保持稳定，这表明可能涉及补偿机制。虽然波动的日粮CP浓度可能会改变瘤胃微生物组，但需要进一步研究瘤胃代谢过程和宿主-微生物组相互作用，以评估我们研究中观察到的变化是否与开发提高奶牛蛋白质营养的新机会具有生物学相关性。
