Enteric fermentation and amino acid economy in pigs

拟议研究的总体目标是更好地了解单胃动物和人类上消化道肠内发酵对膳食氨基酸（AA）摄入量用于身体蛋白质沉积和身体维持功能的影响。据推测，肠道微生物（1）有助于单胃动物和人类上消化道中饮食和内源性AA的分解，（2）优先使用预先形成的AA合成微生物蛋白，即使宿主喂食低蛋白饮食。 这些假设意味着上消化道的微生物发酵对单胃动物和人类的膳食AA需求量有很大贡献。 将进行同位素示踪研究，以量化肠组织和肠道微生物中AA代谢的关键方面，以及生长猪的蛋白质消化。这些研究将补充蛋白质组学和转录组学，以确定和表征饮食对粘膜蛋白质谱和粘膜蛋白质合成调控的影响。拟议的研究将产生定量估计的微生物发酵的贡献，在上消化道的生长猪AA catalysts和净AA供应的宿主动物。 这些估计将用于进一步开发我们的基于生物学的数学模型，该模型代表猪生长的营养利用率，并用于评估替代饲养策略对养猪的经济和环境影响，在教育计划中教授营养利用的原则，并探索需要进一步研究的领域。 提高日粮氮利用率将减少猪对环境退化的贡献，并降低与蛋白质相关的饲养成本。而饲料至少占猪肉生产成本的50%。该研究为培养两名博士生提供了极好的机会。学生和博士后研究员的进一步培训。这些发现可应用于所有单胃农场动物和人类的营养。

The overall aim of the proposed research is to better understand the impact of enteric fermentation in the upper gut of mono-gastric animals and humans, on utilization of dietary amino acid (AA) intake for body protein deposition and body maintenance functions. It is hypothesized that enteric microbes (1) contribute to the catabolism of dietary and endogenous AA in the upper gut of mono-gastric animals and humans, and (2) preferentially use preformed AA for the synthesis of microbial protein, even when the host is fed a low protein diet. These hypotheses imply that microbial fermentation in the upper gut contributes substantially to dietary AA requirements in mono-gastric animals and humans. Isotope tracer studies will be conducted to quantify key aspects of AA metabolism in intestinal tissue and enteric microbes, as well as protein digestion in growing pigs. These studies will be complemented with proteomics and transcriptomics to identify and characterize diet effects on mucosal protein profiles and regulation of synthesis of mucosal proteins. The proposed research will yield quantitative estimates of the contribution of microbial fermentation in the upper gut of growing pigs to AA catabolism and net AA supply to the host animal. These estimates will be used to further develop our biology-based, mathematical model that represents nutrient utilization for growth in the pig and that is used to assess the economic and environmental impacts of alternative feeding strategies growing pigs, teach principles of nutrient utilization in education programs, and to explore areas where further research is needed. Improvements in the efficiency of dietary N utilization will reduce the contribution of pigs to environmental degradation and reduce feeding costs associated with protein. Feed, in turn, represents at least 50% of the cost of pork production. The proposed research will provide an excellent opportunity for training two Ph. D. students and further training of a post-doctoral fellow. The findings have applications for the nutrition of all mono-gastric farm animals and humans.