Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
J Appl Microbiol. 2010 Jun;108(6):1982-93. doi: 10.1111/j.1365-2672.2009.04602.x. Epub 2009 Oct 28.
Understanding factors that influence the composition of microbial populations of the digestive system of dairy cattle will be key in regulating these populations to improve animal performance. Although rumen microbes are well studied, little is known of the dynamics and role of microbial populations in the small intestine of cows. Comparisons of fingerprints of microbial populations were used to investigate the effects of gastrointestinal (GI) segment and animal on community structure.
Samples from four lactating dairy cows with ruminal, duodenal and ileal cannulae were collected. Terminal-restriction fragment length polymorphism (T-RFLP) comparisons of small subunit rRNA genes revealed differences in microbial populations between GI segments (P < 0.05). No significant differences in either methanogen populations or microbial community profiles between animals were observed. Quantitative PCR was used to assay relative changes in methanogen numbers compared to procaryote rRNA gene numbers, and direct microscopic counts were used to enumerate total procaryote numbers of the duodenal and ileal samples.
T-RFLP comparisons illustrate significant changes in microbial diversity as digesta passes from one segment to another. Direct counts indicate that microbial numbers are reduced by eight orders of magnitude from the rumen, through the abomasum, and into the duodenum (from c. 10(12) to c. 3.6 x 10(4) cells per ml). Quantitative PCR analyses of rRNA genes indicate that methanogens are present in the duodenum and ileum.
The contribution of microbial populations of the small intestine to the nutrition and health of cattle is seldom addressed but warrants further investigation.
了解影响奶牛消化系统微生物种群组成的因素对于调控这些种群以改善动物性能至关重要。虽然瘤胃微生物已得到广泛研究，但对于奶牛小肠中微生物种群的动态和作用知之甚少。本研究采用微生物种群指纹图谱比较，研究了胃肠道（GI）段和动物对群落结构的影响。
采集了 4 头泌乳奶牛的瘤胃、十二指肠和回肠插管样本。小亚基 rRNA 基因末端限制性片段长度多态性（T-RFLP）比较显示 GI 段之间微生物种群存在差异（P < 0.05）。未观察到动物之间甲烷菌种群或微生物群落特征存在显著差异。定量 PCR 用于检测甲烷菌数量与原核 rRNA 基因数量的相对变化，直接显微镜计数用于检测十二指肠和回肠样本中总原核数量。
T-RFLP 比较表明，随着食糜从一个段转移到另一个段，微生物多样性发生了显著变化。直接计数表明，微生物数量从瘤胃通过前胃到十二指肠减少了八个数量级（从约 10(12)到约 3.6 x 10(4)个细胞/ml）。rRNA 基因的定量 PCR 分析表明，甲烷菌存在于十二指肠和回肠中。
小肠微生物种群对牛的营养和健康的贡献很少被提及，但值得进一步研究。
