Utility of the carbohydrate larval antigen (CarLA®) saliva test to lower the risk of gastrointestinal parasitism in Ontario sheep flocks

绵羊的胃肠道寄生虫病是牧场生产的一个重要制约因素，需要多方面的方法来长期可持续地控制；其中一种方法是选择能够更好地免疫地管理寄生虫感染(即遗传抗性)的绵羊。这种方法的一个潜在工具是使用Carla唾液测试(AgResearch，新西兰)，该测试测量绵羊对牧场寄生虫感染阶段产生的抗体。最近，圭尔夫大学的研究人员对安大略省南部的一个羊群进行了研究，结果发现，Carla水平处于中高水平的母羊(MH-Carla)的寄生虫粪便卵数(FEC)低于Carla水平较低的绵羊。该项目将通过评估Carla唾液检测在一些鸡群和品种中的实用性来扩大这项工作。通过在两个放牧季节跟踪替代母羊，它将确定MH-Carla母羊羔羊是否与CALA水平较低的羔羊相比，寄生虫水平较低，并且更有可能在第一个放牧季节产下CALA水平较高、生长特性较好和FEC较低的后代。该项目获得的数据将有助于评估Carla唾液测试在安大略省放牧条件下的表现。在其他工作中，将进行经济分析，以估计使用该测试来管理加拿大农场寄生虫的相关经济效益。总的来说，这些发现将有助于将测试从新西兰转移到安大略省的一个诊断实验室，这样它就有可能提供给加拿大各地的绵羊养殖者。该项目的协作者是加拿大绵羊饲养者协会、安大略省养羊人和安大略省农业、食品和农村事务部。

Gastrointestinal parasitism in sheep is a significant constraint to production on pasture and requires a multi-faceted approach for long-term sustainable control; one such approach is to select sheep that are better able to immunologically manage parasite infection (i.e. genetic resistance). One potential tool for this approach is to use The CarLA Saliva Test (AgResearch, New Zealand), which measures antibodies produced by sheep to the infective stage of parasites on pasture. In recent work carried out by researchers at the University of Guelph on one sheep flock in southern Ontario, ewe lambs with medium-to-high CarLA levels (MH-CarLA) had lower parasite fecal egg counts (FEC) than sheep with low CarLA levels. This project will expand this work by evaluating the utility of The CarLA Saliva Test in a number of flocks and breeds. By following replacement ewes over two grazing seasons, it will determine if MH-CarLA ewe lambs, by comparison to those with lower CarLA levels, have lower parasite levels, and are more likely to give birth to offspring with higher CarLA levels, better growth characteristics and lower FEC in their first grazing season. The data obtained by this project will help evaluate the performance of The CarLA Saliva Test under Ontario grazing conditions. In additional work, economic analyses will be carried out to estimate the economic benefit associated with using the test to manage parasites on Canadian farms. Collectively, the findings will facilitate transfer of the test from New Zealand to a diagnostic laboratory in Ontario so that it can potentially be offered to sheep producers across Canada. Collaborators on this project are the Canadian Sheep Breeders' Association, Ontario Sheep Farmers, and the Ontario Ministry of Agriculture, Food and Rural Affairs.