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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=631007
• 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）是奶牛常见的一种代谢性疾病，在此期间，瘤胃pH值每天被抑制数小时。引起这种疾病症状的机制尚未完全了解。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，但也提出了关于这种病因学的新问题。我的研究表明，通过饲喂高谷物饮食进行的SARA挑战与瘤胃液中细菌脂多糖内毒素（LPS）的增加有关，大肠中的细菌脂多糖内毒素（LPS），外周血中的细菌脂多糖内毒素（LPS），以及炎症。SARA的挑战进行喂养饲料含有颗粒的苜蓿也与增加的LPS在瘤胃，但没有相关的LPS在大肠和外周血中，并与炎症。我认为这些SARA挑战之间的差异是由于在基于谷物的SARA挑战期间膳食淀粉含量相对较高。我推测，与苜蓿颗粒SARA挑战相反，基于谷物的SARA挑战增加大肠中的大肠杆菌的酸度和LPS含量，这会导致LPS移位，随后导致全身炎症。利用我新的NSERC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：1。SARA挑战是否会影响消化道上皮细胞的形态，从而使LPS移位并引起全身炎症？2.在SARA挑战期间易位发生在哪里？3.大肠杆菌中淀粉含量是否影响大肠内脂多糖和屏障功能？4.在SARA激发期间观察到的炎症是否与LPS易位有关？该补助金还将用于培训至少1名博士、1名理学硕士，5名本科生。这项研究将为SARA的病因学提供重要见解，同时也将研究营养挑战对消化道屏障功能和牛大肠发酵的影响。