Impact of subacute ruminal acidosis on health of dairy cows

亚急性瘤胃酸中毒对奶牛健康的影响

• 批准号: 238454-2011
• 负责人: Plaizier, Jan
• 金额: $ 2.26万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=506652
• 关键词: Impact; subacute; ruminal; acidosis; health

Subacute ruminal acidosis (SARA) is a common metabolic disease of dairy cows during which the rumen pH is depressed for several hours daily. The mechanisms responsible for the symptoms of this disease are not fully understood. This hinders the diagnosis, prevention, and treatment of SARA. Research conducted during my previous NSERC Discovery Grant provided new insights into the etiology of SARA, but also brought up new questions about this etiology. My research showed that SARA challenges conducted by feeding high-grain diets were associated with increased bacterial lipopolysaccharide endotoxins (LPS) in rumen fluid, in digesta in the large intestine, and in peripheral blood, and with inflammation. SARA challenges conducted by feeding diets containing pellets of ground alfalfa were also associated with increased LPS in the rumen, but were not associated with increased LPS in the large intestine and in peripheral blood, and with inflammation. I believe that the differences between these SARA challenges were due to the comparatively higher dietary starch content during grain-based SARA challenges. I hypothesize that, in contrast to alfalfa-pellet SARA challenges, grain-based SARA challenges increase the acidity and LPS content of digesta in the large intestine, and that this causes translocation of LPS and, subsequently, systemic inflammation. Using my new NSERC Discovery Grant, I will answer to following questions to test my hypotheses by conducting in vivo experiments with cattle: 1. Do SARA challenges affect the morphology of the epithelia of the digestive tract in a manner that enables translocation of LPS and causes systemic inflammation?; 2. Where do translocations during SARA challenges occur?; 3. Does the starch content of digesta in the large intestine affect LPS and barrier function in the large intestine?; 4. Is the inflammation observed during SARA challenges related to translocation of LPS? The grant will also be used to train at least 1 Ph.D, 1 M.Sc., and 5 undergraduate students. This research will provide critical insights in the etiology of SARA, but also on the effects of nutritional challenges on the barrier function of the digestive tract and on fermentation in the large intestine in cattle.

亚急性瘤胃酸中毒（SARA）是奶牛常见的代谢性疾病，发病期间瘤胃pH值每天下降数小时。造成这种疾病症状的机制尚不完全清楚。这阻碍了SARA的诊断、预防和治疗。在我之前的NSERC发现资助期间进行的研究为SARA的病因学提供了新的见解，但也提出了关于这一病因学的新问题。我的研究表明，饲喂高谷物日粮引发的SARA挑战与瘤胃液、大肠食糜和外周血中细菌脂多糖内毒素（LPS）的增加以及炎症有关。通过饲喂含有苜蓿粉颗粒的饲料进行SARA挑战也与瘤胃内LPS升高有关，但与大肠和外周血中LPS升高无关，也与炎症无关。我认为这些SARA挑战之间的差异是由于谷物为基础的SARA挑战中相对较高的膳食淀粉含量。我假设，与紫花苜蓿颗粒的SARA挑战相反，谷物为基础的SARA挑战增加了大肠食糜的酸度和LPS含量，这导致LPS易位，随后引起全身炎症。利用我新的国家科学研究委员会发现基金，我将回答以下问题，通过对牛进行体内实验来验证我的假设：SARA挑战是否会影响消化道上皮的形态，从而使LPS易位并引起全身性炎症？2. 在SARA挑战中易位发生在哪里？3. 大肠食糜淀粉含量是否影响LPS和大肠屏障功能？4. SARA挑战期间观察到的炎症是否与LPS易位有关？该基金还将用于培养至少1名博士、1名硕士和5名本科生。这项研究将为SARA的病因学提供重要的见解，也将为营养挑战对牛消化道屏障功能和大肠发酵的影响提供重要的见解。