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Impacts of Ruminal Acidosis on Animal Health and Performance


Subacute Ruminal Acidosis (SARA) resulting from a grain overload has been associated with increases of lipopolysaccharide (LPS) in digesta and blood,as well as signs of inflammation,such as an acute phase response.This response is part of the innate immune system and is characterized by elevated levels ofserum amyloid A (SAA),haptoglobin (Hp),and LPS binding protein (LBP)in the blood.Production of these acute phase proteins is driven by a variety of cytokines that include interleukin 6 (IL-6),tumor necrosis factor α (TNFαt).It is assumed that the production of these cytokines is activated when LPS-LBP complexes bind with toll-like receptors (TLR),such as TLR-4.Intravenous administration of LPS derived from E.colicause log-fold rises of SAA,HP,LBP,IL-6 and TNFαt in blood plasma,as well as fever and a leukocyte count response.It has become clear that LPS needs to translocate through the epithelium of the digestive tract in order to activate TLR.Detection of LPS in peripheral bloodand a reduction of the barrier function of the epithelia of the rumenand the large intestine,suggest that this translocation may occur during SARA.However,these studies have not been able to identify the sites through which LPS or other immunogenic compounds may betranslocated.Gross anatomical and histological differences in the epithelium of the rumen and the large intestine suggest that hindgut acidosis may create a greater risk for LPS translocation than rumen acidosis.Measurement of LPS in the blood of cows during SARA suggests that the amount of LPS that is translocated during SARA is similar to the doses that have been used during studies in which E.coli LPS was administered intravenously to cows.In contrast to intravenous injection of LPS,experimentally induced SARA is generally not associated with fever,changes in leucocyte count,or massive increases in acute phase proteins and cytokines.One reason for this discrepancy may be that the toxicity of enteric LPS from cattle may be lower than that from the E.coli that was administered intravenously.Another reason for this discrepancy may be an endotoxin tolerance that is developed by continuous exposure to LPS during SARA and that is not developed during a one-time intravenous administration of LPS.The mechanism behind tolerance to repeated exposure to LPS is not yet well understood.A better understanding of this mechanism will contribute to strategies that enhance health and welfare of ruminants on high grain diets.......

【作者名称】: J.C Plaizier, S.C.Li, G.N.Gozho, A.M.Danscher, E.Khafipour, G.Penner
【作者单位】: University of Manitoba, Canada, University of Manitoba, Canada, University of Manitoba, Canada, University of Copenhagen, Denmark, University of Manitoba, Canada, University of Saskatchewan, Canada
【关 键 词】: Impacts of Ruminal Acidosis on Animal Health and Performance
【会议名称】: 4th international symposium on dairy cow nutrition and milk quality proceedings
【期刊论文数据库】: [DBS_Articles_01]
【期刊论文编号】: 101,065,224
【摘要长度】: 2,487
【会议地点】: Beijing(CN)
【会议组织】: University of Manitoba, Canada;University of Manitoba, Canada;University of Manitoba, Canada;University of Copenhagen, Denmark;University of Manitoba, Canada;University of Saskatchewan, Canada;Swedish Agricultural University, Sweden;;
【会议时间】: 2015
【上篇论文】: 外文会议 - Supplying Energy Needs of the Dairy Cow through Fat Supplementation
【下篇论文】: 外文会议 - Effects of nitrogen addition and increased precipitation on soil hydrolytic enzyme activities in a temperate meadow steppe

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