Rodríguez-Lecompte J C, Kroeker A D, Ceballos-Márquez A, Li S, Plaizier J C, Gomez D E
Department of Animal Science, University of Manitoba, Winnipeg, MB, Canada R3T 2N2.
J Dairy Sci. 2014 Dec;97(12):7777-87. doi: 10.3168/jds.2014-8319. Epub 2014 Oct 18.
Subacute ruminal acidosis (SARA) increases lipopolysaccharide endotoxin in the rumen, which might translocate into the systemic circulation, triggering a cascade of clinical and immunological alterations. The objective of this study was to characterize the clinical immune and metabolic responses to ruminal-derived lipopolysaccharide in nonlactating cows induced with SARA using 2 challenges, a grain-based SARA challenge (GBSC) or an alfalfa-pellet SARA challenge (APSC). Six dry, nonlactating Holstein cows were used in a 3 × 3 Latin square arrangement of treatments with 4-wk experimental cycles. All cows received the control diet containing 70% forage and 30% mixed concentrates (dry matter basis) for 3 wk. In wk 4, cows received a control diet, GBSC (38% wheat-barley pellets, 32% other mixed concentrate, and 30% forages), or APSC (45% mixed concentrate, 32% alfalfa pellets, and 23% other forages). Total plasma proteins and immunology-related proteins, acute phase proteins, blood cells, serum chemistry, mRNA gene expression of peripheral blood cell surface markers, and selected proinflammatory cytokines were evaluated. Ruminal pH was lower in both groups with induced SARA compared with a control group. Ruminal endotoxins were higher in GBSC; however, plasma endotoxin was not detected in any study group. No significant differences in feed intake, rectal temperature, white blood cell counts, or differentials were found between control and SARA challenge groups; changes in glucose, urea, Ca, and Mg were observed in SARA groups. Total plasma proteins were lower in both SARA groups, and acute phase proteins were higher in GBSC. The expression of CD14, MD2, and TLR4 mRNA in peripheral blood leukocytes was not affected by SARA induction. The induction of SARA as a result of GBSC or APSC challenge was successful; however, LPS was not detected in plasma. Changes in clinical, metabolic, and inflammatory responses were not observed in the SARA-challenged cows, suggesting that, in this study, SARA was not associated with a systemic response to inflammation.
亚急性瘤胃酸中毒（SARA）会增加瘤胃中的脂多糖内毒素，这些内毒素可能会转移至体循环，引发一系列临床和免疫改变。本研究的目的是利用两种挑战，即谷物型SARA挑战（GBSC）或苜蓿颗粒型SARA挑战（APSC），来描述非泌乳奶牛对瘤胃源性脂多糖的临床免疫和代谢反应。选用6头干奶期的非泌乳荷斯坦奶牛，采用3×3拉丁方设计，每个试验周期为4周。所有奶牛在3周内均采食含70%粗饲料和30%混合精料（干物质基础）的对照日粮。在第4周，奶牛分别采食对照日粮、GBSC（38%小麦-大麦颗粒、32%其他混合精料和30%粗饲料）或APSC（45%混合精料、32%苜蓿颗粒和23%其他粗饲料）。评估了总血浆蛋白、免疫相关蛋白、急性期蛋白、血细胞、血清生化指标、外周血细胞表面标志物的mRNA基因表达以及选定的促炎细胞因子。与对照组相比，两组诱导SARA的奶牛瘤胃pH均较低。GBSC组瘤胃内毒素含量较高；然而，在任何研究组中均未检测到血浆内毒素。对照和SARA挑战组之间在采食量、直肠温度、白细胞计数或分类方面未发现显著差异；SARA组观察到葡萄糖、尿素、钙和镁的变化。两组SARA组的总血浆蛋白均较低，GBSC组的急性期蛋白较高。外周血白细胞中CD14、MD2和TLR4 mRNA的表达不受SARA诱导的影响。GBSC或APSC挑战导致的SARA诱导成功；然而，血浆中未检测到LPS。在SARA挑战的奶牛中未观察到临床、代谢和炎症反应的变化，表明在本研究中，SARA与炎症的全身反应无关。
