Enteric fermentation and amino acid economy in pigs

本研究的总体目的是为了更好地了解单胃动物和人类上肠的肠道发酵对饲料中氨基酸（AA）摄入量用于体内蛋白质沉积和身体维持功能的影响。据推测，肠道微生物(1)在单胃动物和人类的上肠中参与了日粮和内源性AA的分解代谢，(2)即使宿主被喂食低蛋白饮食，也优先利用预形成的AA合成微生物蛋白。这些假设表明，在单胃动物和人类中，上肠道的微生物发酵在很大程度上决定了饮食中AA的需求。将进行同位素示踪研究，以量化生长猪肠道组织和肠道微生物中AA代谢的关键方面，以及蛋白质消化。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谱的影响以及对粘膜蛋白合成的调节。拟议的研究将定量估计生长猪上肠微生物发酵对宿主动物AA分解代谢和AA净供应的贡献。这些估计将用于进一步发展我们基于生物学的数学模型，该模型代表猪生长中的营养利用，用于评估替代饲养策略对生长猪的经济和环境影响，在教育计划中教授营养利用原理，并探索需要进一步研究的领域。饲粮氮利用效率的提高将减少猪对环境退化的贡献，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%。本研究将为培养两名博士研究生和进一步培养一名博士后提供良好的机会。这一发现对所有单胃农场动物和人类的营养都有应用价值。

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.