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肠道的肠道发酵对人体蛋白质沉积和身体维护功能利用膳食氨基酸(AA)的影响。假设肠道微生物(1)促进单胃动物和人类上肠道内食物和内源性AA的分解代谢，(2)优先使用预制的AA合成微生物蛋白质，即使宿主饲喂低蛋白饲料。这些假设表明，在单胃动物和人类中，上肠道的微生物发酵对膳食AA的需求有很大贡献。将进行同位素示踪研究，以量化肠道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。这些研究将与蛋白质组学和转录组学相辅相成，以确定和表征饮食对粘膜蛋白质谱的影响和对粘膜蛋白质合成的调节。这项拟议的研究将对生长猪上肠道微生物发酵对AA分解代谢和宿主动物AA净供应的贡献进行定量估计。这些估计将被用来进一步开发我们的基于生物学的数学模型，该模型代表了猪生长所需的营养利用，用于评估替代饲养策略对经济和环境的影响，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。饲料氮利用效率的提高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。反过来，饲料至少占猪肉生产成本的50%。拟议的研究将为培训两名博士生和进一步培训一名博士后提供一个极好的机会。这一发现适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.