Rhodes M T, Paterson J A, Kerley M S, Garner H E, Laughlin M H
Dept. of Anim. Sci., University of Missouri, Columbia 65211.
J Anim Sci. 1991 May;69(5):2033-43. doi: 10.2527/1991.6952033x.
Four wethers and 14 steers (environmentally heat stressed, 32 degrees C, 60% relative humidity) were evaluated for changes in blood flow induced by endophyte-infected tall fescue. Concentration of the ergopeptide ergovaline was used as an indicator of diet toxicity due to the endophytic fungus Acremonium coenophialum. Blood flow to specific tissues was measured using radiolabeled microspheres. Wethers received one of two dietary treatments for 30 d before determination of tissue blood flow: 1) a low-endophyte diet (less than .05 ppm ergovaline) or 2) a high-endophyte (1.18 ppm ergovaline) diet. Blood flows to the adrenal glands and skin covering the inner hind leg were less (P less than .10) in wethers consuming the high-endophyte diet than in those consuming the low-endophyte diet. Tissue blood flows in steers were determined on two occasions: 1) after steers had received a low- (less than .01 ppm ergovaline) or high-endophyte (.52 ppm ergovaline) fescue diet for 14 d and 2) 8 d after steers had been switched to a common, fescue-free diet. Blood flows to skin covering the ribs, cerebellum of the brain, duodenum, and colon were less (P less than .10) in steers consuming the high-endophyte diet. However, 8 d after consuming fescue-free diets, steers that had previously consumed the high-endophyte diet had greater (P = .08) blood flow to the coronary bands of the front hooves than steers that had consumed the low-endophyte diet. Blood flows to all other tissues were similar between treatments. We inferred from these experiments that the toxin(s) associated with endophyte-infected tall fescue caused decreased blood flow to peripheral and core body tissues and that this effect was abated within 8 d of removing the toxin(s).
对4只阉羊和14头公牛（处于环境热应激状态，温度32摄氏度，相对湿度60%）进行评估，以研究内生真菌感染的高羊茅引起的血流变化。麦角肽麦角新碱的浓度被用作内生真菌禾本科内生真菌引起的日粮毒性指标。使用放射性标记微球测量特定组织的血流。在测定组织血流前30天，阉羊接受两种日粮处理之一：1）低内生真菌日粮（麦角新碱含量低于0.05 ppm）或2）高内生真菌（麦角新碱含量1.18 ppm）日粮。采食高内生真菌日粮的阉羊，其肾上腺和后肢内侧皮肤的血流比采食低内生真菌日粮的阉羊少（P<0.10）。在两个时间点测定公牛的组织血流：1）公牛接受低（麦角新碱含量低于0.01 ppm）或高内生真菌（麦角新碱含量0.52 ppm）高羊茅日粮14天后；2）公牛转为普通无高羊茅日粮8天后。采食高内生真菌日粮的公牛，其肋骨皮肤、脑小脑、十二指肠和结肠的血流较少（P<0.10）。然而，采食无高羊茅日粮8天后，之前采食高内生真菌日粮的公牛前蹄冠状带的血流比采食低内生真菌日粮的公牛多（P = 0.08）。各处理间所有其他组织的血流相似。我们从这些实验推断，与内生真菌感染的高羊茅相关的毒素导致外周和核心身体组织的血流减少，并且在去除毒素8天内这种影响减弱。
