Proanthocyanidin (PAC, condensed tannin) containing forages have well-documented anti-parasitic effects against gastrointestinal nematodes (GIN) of small ruminants. Although extensive research has been conducted on the inhibition of exsheathment of the L₃ stage of Haemonchus contortus by in vitro exposure to the extracts of PAC containing plants, only one study has previously attempted to replicate this process in vivo and it was found that consumption of fresh sainfoin slowed the exsheathment rate. No similar studies have explored the effect of feeding condensed tannin forages in the form of hay on in vivo exsheathment of GIN. Another PAC containing forage, birdsfoot trefoil (Lotus corniculatus, BFT), has a large area of adaptation globally and feeding BFT has been shown to reduce fecal egg counts and total worm burdens. However, its effect on the in vivo exsheathment of H. contortus in the rumen is unknown. Recent work from this laboratory showed that BFT populations differ in the ability of aqueous extracts of freeze-dried plants to reduce exsheathment of H. contortus in vitro, and that the reduced exsheathment caused by BFT populations did not directly correlate with PAC content. Therefore, the objective of this study was twofold: 1) to evaluate the ability of birdsfoot trefoil hay to impair ruminal exsheathment of H. contortus in vivo and 2) to measure the difference in exsheathment between three commercially available cultivars of birdsfoot trefoil representing a broad range of in vitro efficacy against H. contortus. Four rumen fistulated ewes were fed three cultivars of birdsfoot trefoil (cv. Bruce, Empire, and Pardee) hay or a control hay (alfalfa/grass hay) in a Latin 4 × 4 design. The effect of consumption of birdsfoot trefoil on the exsheathment of H. contortus larvae in vivo was evaluated. For each exsheathment test, two capsules with 2000 ensheathed third-stage larvae per capsule were placed in the rumen of each ewe for eight hours. Larval containment capsules were made by capping each end of a short piece of Tygon® tubing (ID 9.5 mm, OD 14.3 mm) with an 8 μm Nunc^TM Cell Culture Insert. Larval exsheathment and motility were examined pre and post rumen exposure. Three exsheathment tests were run per diet cycle. Consumption of BFT hay did not significantly alter larval exsheathment. These results highlight the importance of further in vivo testing on the role of condensed tannins and other plant secondary compounds on larval exsheathment in the rumen.

含有原花青素（PAC，缩合单宁）的饲料对小反刍动物胃肠道线虫（GIN）具有明显的抗寄生虫作用。尽管通过体外暴露于含有 PAC 的植物提取物来抑制捻转血矛线虫L ₃阶段的外鞘已经进行了广泛的研究，但之前只有一项研究尝试在体内复制这一过程，并且发现食用新鲜的红枫可减慢出鞘速度。没有类似的研究探讨以干草形式饲喂缩合单宁草料对 GIN体内脱皮的影响。另一种含有草料的 PAC，即百脉根（ Lotus corniculatus ，BFT），在全球范围内具有很大的适应性，饲喂 BFT 已被证明可以减少粪便中的虫卵数量和总蠕虫负担。然而，其对H. contortus在瘤胃中体内脱鞘的影响尚不清楚。该实验室最近的工作表明，BFT 群体在冻干植物水提取物减少H. contortus 体外鞘的能力方面存在差异，并且 BFT 群体引起的外鞘减少与 PAC 含量没有直接关系。因此，本研究的目的是双重的：1) 评估三叶草干草在体内损害 H. contortus瘤胃外鞘的能力，2) 测量代表广泛的三叶草市售品种之间的外鞘差异。针对H. contortus 的体外功效范围。 四只瘤胃瘘管母羊按照拉丁 4 × 4 设计饲喂三种鸟足三叶草（布鲁斯、帝国和帕迪）干草品种或对照干草（苜蓿/草干草）。评估了食用三叶草对捻转蝽幼虫体内脱鞘的影响。对于每次出鞘测试，将两个胶囊放入每只母羊的瘤胃中八小时，每个胶囊中含有2000个出鞘的第三阶段幼虫。通过用 8 μm Nunc ^TM细胞培养插管盖住一小段 Tygon® 管（内径 9.5 毫米，外径 14.3 毫米）的两端，制成幼虫遏制胶囊。在瘤胃暴露之前和之后检查幼虫的脱鞘和运动性。每个饮食周期进行三次拔鞘测试。食用 BFT 干草并没有显着改变幼虫的脱鞘。这些结果强调了进一步体内测试缩合单宁和其他植物次生化合物对瘤胃幼虫脱鞘作用的重要性。