Fescue toxicosis poses a significant challenge to the United States beef industry, resulting in considerable economic losses. This syndrome arises from the consumption of tall fescue (Schedonorus arundinaceous) infected with the wild-type endophyte (WE; Epichloe coenophiala), which produces toxic alkaloids. The most effective solution for mitigating fescue toxicosis is renovating WE tall fescue pastures to novel endophyte-infected (NE) tall fescue. However, pasture renovation is costly and may not be feasible under certain conditions, with the economic profitability taking up to 3 yr. While the potential of condensed tannins (CTs) in specific leguminous forages to reduce the absorption of toxic alkaloids is recognized, their use as supplements remains underexplored. This study aims were to investigate the potential of CT-containing feed supplements, specifically sericea lespedeza (Lespedeza cuneata) pellets, in reducing the post-ingestive effects of fescue toxicosis in steers. Over two summers,12 steers were assigned to either Schedonorus arundinaceous (LES) or LES mixed with polyethylene glycol (LES + PEG) as a positive control for 12 wk. Body weight, hair retention score, rectal and extremities temperatures, cortisol concentrations, and lumen area of caudal arteries were collected at 4-wk intervals. Data were analyzed using a mixed-effect ANOVA test in SAS Studio 3.5. Steers on the LES diet exhibited significantly less (P < 0.05) hair retention scores compared with those on the LES + PEG diet. In 2021, steers on the LES diet showed greater (P = 0.0101) ADG, while in 2022, there was no difference (P = 0.9916) in ADG between the treatments. Steers on the LES diet displayed greater (P = 0.0332) tail skin temperatures and decreased (P < 0.0001) rectal temperatures compared with those on the LES + PEG diet. Hair cortisol concentrations were greater (P < 0.05) in steers on the LES + PEG diet than in those on the LES diet. Additionally, steers supplemented with the LES + PEG diet showed a 21.2% smaller caudal artery lumen area compared with those on the LES diet (P < 0.01). These findings underscore the potential of CTs in reducing the post-ingestive effects of fescue toxicosis. However, further research is needed to explore the complex mechanisms underlying these effects, establish the long-term efficacy of such interventions, and extend the investigation to include a broader range of physiological parameters affecting livestock health and performance.

中文翻译：

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161 胡枝子补充剂对放牧野生型内生菌感染高羊茅的小牛的影响

羊茅中毒给美国牛肉产业带来了重大挑战，造成了相当大的经济损失。这种综合症是由于食用了感染野生型内生菌（WE；Epichloe coenophiala）的高羊茅（Schedonorus arundinaceous）而引起的，这种内生菌会产生有毒的生物碱。减轻羊茅中毒的最有效解决方案是将 WE 高羊茅牧场改造为新型内生菌感染 (NE) 高羊茅。然而，牧场改造成本高昂，在某些条件下可能不可行，经济盈利需要长达3年的时间。虽然人们认识到特定豆科牧草中的缩合单宁 (CT) 具有减少有毒生物碱吸收的潜力，但它们作为补充剂的用途仍未得到充分探索。本研究的目的是调查含 CT 的饲料补充剂，特别是绢毛胡枝子 (Lespedeza cuneata) 颗粒，在减少阉牛羊茅中毒摄入后影响方面的潜力。在两个夏天，12 头公牛被分配到 Schedonorus arundinaceous (LES) 或 LES 与聚乙二醇混合 (LES + PEG) 作为阳性对照，为期 12 周。每 4 周收集一次体重、毛发保留评分、直肠和四肢温度、皮质醇浓度和尾动脉管腔面积。使用 SAS Studio 3.5 中的混合效应 ANOVA 测试对数据进行分析。与食用 LES + PEG 饮食的公牛相比，使用 LES 饮食的公牛表现出显着较低（P < 0.05）的毛发保留分数。2021 年，采用 LES 饮食的公牛显示出更高的平均日增重 (P = 0.0101)，而在 2022 年，各处理之间的平均日增重没有差异 (P = 0.9916)。与吃 LES + PEG 饮食的牛相比，吃 LES 饮食的牛表现出更高的尾部皮肤温度 (P = 0.0332) 和更低的直肠温度 (P < 0.0001)。吃LES+PEG饮食的小公牛的毛皮质醇浓度比吃LES饮食的小公牛的毛皮质醇浓度更高(P＜0.05)。此外，补充 LES + PEG 饮食的公牛的尾动脉管腔面积比 LES 饮食的公牛小 21.2%（P < 0.01）。这些发现强调了 CT 在减少羊茅中毒摄入后影响方面的潜力。然而，还需要进一步研究来探索这些影响背后的复杂机制，确定此类干预措施的长期功效，并将研究范围扩大到影响牲畜健康和生产性能的更广泛的生理参数。