Williams M, Shaffer S R, Garner G B, Yates S G, Tookey H L, Kintner L D, Nelson S L, McGinity J T
Am J Vet Res. 1975 Sep;36(9):1353-7.
Tall fescue (Festuca arundinacea Shreb) hay from a source known to cause "fescue foot" in grazing cattle was extracted with 80% ethanol. The ethanolic extract was further refined and fractionated into cation,nion, and neutral f fractions by ion-exchange chromatography. The cation fraction was partitioned with alkaline-chloroform to give chloroform-extractable cation and residual cation fractions. All fractions plus the crude ethanolic extract were assayed for toxic activity by intraperitoneal injection into 12 calves (weighting 152.4 to 241.3 kg each) over a 14-day period. Clinical signs of fescue foot were observed on the 5th day in calves given the anion and crude ethanolic extracts. Lameness, swelling, and reddening of the rear coronary bands, discoloration of the tip of the tail, and other signs of fescue foot were seen. Microscopically, coronary bands and tail tips of affected calves had blood vessels with thick walls and small lumens.
从已知会导致放牧牛出现“牛尾草中毒性蹄病”的来源获取的牛尾草（高羊茅）干草，用80%乙醇进行提取。乙醇提取物进一步精制，并通过离子交换色谱法分离成阳离子、阴离子和中性组分。阳离子组分用碱性氯仿进行分配，得到可氯仿萃取的阳离子组分和残留阳离子组分。在14天的时间里，通过腹腔注射将所有组分以及粗乙醇提取物对12头犊牛（每头体重152.4至241.3千克）进行毒性活性测定。在给予阴离子和粗乙醇提取物的犊牛中，于第5天观察到牛尾草中毒性蹄病的临床症状。出现了跛行、后冠状带肿胀和发红、尾尖变色以及牛尾草中毒性蹄病的其他症状。在显微镜下，受影响犊牛的冠状带和尾尖的血管壁增厚且管腔狭小。
