Microbial ecology and nutrient fermentation in the upper gastrointestinal tract of poultry

动物的胃肠道是由一个丰富多样的正常非致病菌群落定植的，这些细菌对宿主既有有益的作用，也有有害的作用。对宿主有益的例子包括排除病原体和合成必需维生素。对宿主的有害影响包括微生物发酵或对某些选定营养物质的竞争，增加对某些营养物质的需求，降低消化和吸收能力。在家禽中，细菌数量最多的地方是在嗉囊、上消化道的食道外袋和靠近消化道末端的成对盲囊（称为盲肠）。本项目将侧重于利用基于基因组DNA核苷酸序列的分子技术确定家禽作物中细菌的数量和种类。我们将确定饲养策略和日粮组成的差异如何影响作物中细菌的组成、数量和发酵活性。大多数商业动物饲料都添加了一些相对昂贵的成分，如氨基酸，以满足它们的营养需求。由于作物的细菌有机会在宿主吸收它们自己使用之前通过发酵利用营养物质，我们将确定这种情况发生的程度以及改变喂养策略的影响。

The gastrointestinal tract of animals is colonized by an abundant and diverse community of normal non-pathogenic bacteria which have both beneficial and detrimental effects on their host. Examples of benefits to the host include exclusion of pathogens and synthesis of essential vitamins. Detrimental effects on the host include microbial fermentation or competition for certain selected nutrients, increasing the requirement for certain nutrients and reducing digestive and absorptive capacity. In poultry, the largest bacterial populations are found in the crop, an out pouching of the oesophagus in the upper tract and in paired blind sacs near the end of the tract termed ceca. This project will focus on determining the number and species of bacteria in the crop of poultry using molecular techniques based on nucleotide sequence of genomic DNA. We will determine how differences in feeding strategies and diet composition affect the composition, number and fermentation activity of bacteria in the crop. Most commercial animal diets are supplemented with a number of relatively expensive ingredients such as amino acids in order to meet their nutrient requirements. Since bacteria of the crop have opportunity to utilize the nutrients by fermentation before the host can absorb them for their own use, we will determine the extent to which this occurs and impact of changing feeding strategies.