McLaughlin C L, Thompson A, Greenwood K, Sherington J, Bruce C
Pfizer Animal Health, 7000 Portage Road, Kalamazoo, MI 49001, USA.
J Dairy Sci. 2009 Jun;92(6):2758-66. doi: 10.3168/jds.2008-1602.
A challenge model was used to evaluate a new approach to controlling acute acidosis. Acute acidosis reduces performance in both dairy and beef cattle and most often occurs as a consequence of ingestion of large amounts of readily fermentable starch, resulting in increased production of volatile fatty acids (VFA) and lactic acid and a reduction in ruminal pH. Acarbose is an alpha-amylase and glucosidase inhibitor that slows the rate of degradation of starch to glucose, thereby reducing the rate of VFA production and maintaining rumen pH at a more stable level. It is commercially available (Glucobay, Bayer, Wuppertal, Germany) and indicated for the control of blood glucose in diabetic patients. The ability of acarbose to reduce the incidence of acidosis and the comparative efficacies of acarbose, sodium bicarbonate, and monensin were tested in 3 acute acidosis challenge experiments in cattle. Rumen-cannulated Holstein steers were challenged with a mixture of 48.4% cornstarch, 48.4% ground corn, 2.1% sodium caseinate, and 1.1% urea with or without test substance. The challenge was administered at a rate of 12.5 g/kg of body weight (BW) as a slurry through the cannula directly into the rumen. Ruminal pH was monitored at 10-min intervals throughout the study. Animals were removed from study and rumen contents replaced if they exhibited acute acidosis as defined as pH <4.5. If acidosis was not observed within 24 h, animals were subjected to a second challenge. Ruminal fluid samples were taken for measurement of VFA and lactate concentrations at various intervals after the challenge. In experiment 1, the carbohydrate challenge induced acidosis in 4 of 4 control animals and 0 of 4 animals treated with 2.14 or 21.4 mg of acarbose/kg of BW in the challenge based on the criterion of pH <4.5. In experiment 2, the carbohydrate challenge induced acidosis in 4 of 7 control animals and 1 of 7 animals when 1.07 mg of acarbose/kg of BW was included in the challenge. In experiment 3, acidosis was induced in 7 of 7 animals in the control, 1% sodium bicarbonate, and 12 mg of monensin/kg of dry matter intake groups and in 3 of 8 steers administered 1.07 mg of acarbose/kg of BW in the challenge. Increases in lactate concentrations and decreases in total VFA associated with acute acidosis were mitigated by acarbose. Thus, acarbose, an amylase and glucosidase inhibitor, prevented or reduced the incidence of acidosis in an acute challenge model in steers and was more effective than monensin or sodium bicarbonate.
采用一种挑战模型来评估控制急性酸中毒的新方法。急性酸中毒会降低奶牛和肉牛的生产性能，最常见的原因是摄入大量易于发酵的淀粉，导致挥发性脂肪酸（VFA）和乳酸产量增加，瘤胃pH值降低。阿卡波糖是一种α-淀粉酶和葡萄糖苷酶抑制剂，它能减缓淀粉降解为葡萄糖的速度，从而降低VFA的产生速度，并将瘤胃pH值维持在更稳定的水平。它已上市销售（拜糖平，德国伍珀塔尔市拜耳公司），用于控制糖尿病患者的血糖。在3项牛急性酸中毒挑战实验中，测试了阿卡波糖降低酸中毒发生率的能力以及阿卡波糖、碳酸氢钠和莫能菌素的相对疗效。给装有瘤胃瘘管的荷斯坦公牛投喂含有48.4%玉米淀粉、48.4%粉碎玉米、2.1%酪蛋白酸钠和1.1%尿素的混合物，其中添加或不添加受试物质。以12.5 g/kg体重（BW）的剂量将该混合物制成浆液，通过瘘管直接注入瘤胃进行挑战。在整个研究过程中，每隔10分钟监测一次瘤胃pH值。如果动物出现定义为pH<4.5的急性酸中毒，则将其从研究中剔除并更换瘤胃内容物。如果在24小时内未观察到酸中毒，则对动物进行第二次挑战。在挑战后的不同时间间隔采集瘤胃液样本，测量VFA和乳酸浓度。在实验1中，根据pH<4.5的标准，在挑战中，4只对照动物中有4只因碳水化合物挑战诱发了酸中毒，而4只接受2.14或21.4 mg阿卡波糖/kg BW治疗的动物中无一只发生酸中毒。在实验2中，当挑战中包含1.07 mg阿卡波糖/kg BW时，7只对照动物中有4只因碳水化合物挑战诱发了酸中毒，7只动物中有1只发生酸中毒。在实验3中，对照、1%碳酸氢钠和12 mg莫能菌素/kg干物质采食量组的7只动物均因挑战诱发了酸中毒，而在挑战中接受1.07 mg阿卡波糖/kg BW的8头公牛中有3只发生了酸中毒。阿卡波糖减轻了与急性酸中毒相关的乳酸浓度升高和总VFA降低。因此，阿卡波糖这种淀粉酶和葡萄糖苷酶抑制剂在公牛急性挑战模型中预防或降低了酸中毒的发生率，且比莫能菌素或碳酸氢钠更有效。
