摘要
Feed efficiency affects profitability and sustainability in beef production systems. Since ruminal microbes play essential roles in feed digestion and conversion, the overall objective of this project was to investigate the association between ruminal bacteria and feed efficiency of beef cattle. PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) was applied to investigate ruminal microbial communities. A statistical model was developed to link the PCR-DGGE band patterns to host phenotypic measurements such as feed efficiency and rumen fermentation variables. Therefore, we determined how the numbers and species of ruminal bacteria present varied dependently as well as independently from diet and their associations with feed efficiency. Likewise, the impact of these interactions on the metabolic capacity and feed efficiency of the host was assessed. Study 1 demonstrated that particular bacteria in the rumen contributed to differences in feed efficiency when host was fed low energy diet. Study 2 evaluated whether structure of bacterial populations remained stable in spite of the dietary changes; we also determined how specific bacterial groups could impact the feed efficiency under low and high energy density diets. Populations of three bacterial species ( Succinivibrio sp., Eubacterium sp., and Robinsoniella sp.) were identified to be correlated with feed efficiency measurements; their predicted metabolic mechanisms influencing feed efficiency were proposed (propionate synthesis, formate production and cross-feeding interaction with methanogens). Furthermore, host factors were elucidated in Study 3. Frequency analysis of bacterial PCR-DGGE bands showed that Prevotella sp. was abundant in Angus rumen liquid and contents while Clostridium sp. was present in contents and tissue from Charolais steers. Rumen tissue from Hybrid animals presented high frequency of Prevotella sp. but no species were particularly abundant in liquid, suggesting a strong association between host and the colonization of rumen bacteria. This is the first study linking rumen microbial diversity and microbial metabolites to host feed efficiency traits and their implications on individual variations in Residual Feed Intake of beef cattle.
摘要译文
饲料效率影响盈利能力和可持续发展的牛肉生产体系。由于瘤胃微生物饲料的消化和转化发挥重要作用，该项目的总体目标是研究瘤胃细菌和肉牛的饲料效率之间的关系。PCR的变性梯度凝胶电泳（PCR-DGGE）施加到调查瘤胃微生物群落。统计模型来链接PCR-DGGE带图案的表型主机测量，如饲料效率和瘤胃发酵的变量。因此，我们确定如何瘤胃细菌的数量和种类，从目前的饮食和它们与饲料效率变化依赖性以及独立。同样地，对宿主的代谢能力和饲料效率这些相互作用的影响进行了评估。研究1证明了在瘤胃特定细菌造成饲料效率差异，当主机饲喂低能量的饮食。2研究评估，尽管在饮食结构的改变细菌种群的结构是否保持稳定;我们还确定特异性细菌群体如何影响下低和高能量密度日粮饲料效率。被鉴定为与饲料效率的测量相关联3种细菌的种群（Succinivibrio属，真杆菌属，和Robinsoniella藻。）;其影响饲料利用率预测的代谢机制，提出了（丙酸合成，甲酸生产和交叉喂养甲烷交互）。此外，宿主因素分别鉴定在研究3.频率细菌的PCR-DGGE条带的分析表明，普雷沃菌。是丰富的安格斯瘤胃液体和梭状芽孢杆菌，而SP的内容。是目前在内容和组织从夏洛来公牛。从混合动物瘤胃组织提出普雷沃菌的高频率。但没有种为液体特别丰富，这表明主机和瘤胃细菌的定植之间有很强的相关性。这是第一次研究连接瘤胃微生物多样性和微生物的代谢产物主办饲料效率性状和肉牛剩余采食量个体差异的影响。
Hernandez Sanabria, Emma. Associations between Rumen Bacteria and Feed Efficiency in Beef Cattle[D]. CA: University of Alberta (Canada), 2011