胃肠道线虫(GINs)是全球绵羊生产可持续性的重大威胁。围产期母羊在GIN流行病学中起着关键作用,这些母羊的GIN粪便卵数(FECs)增加,导致牧场严重污染,从而在放牧期间后期促进免疫幼稚羔羊的寄生性胃肠炎。传统上,覆盖驱虫药处理会抑制这些母羊的GIN卵产量和随后的牧场污染。然而,现在建议农民实施针对性选择性治疗(TST),以减少驱虫药的使用和随后的驱虫药耐药性的发展,然而,目前,确定母羊最佳TST策略的证据有限。在这项研究中,使用负二项混合模型分析,对7只威尔士农场的226只母羊进行了产仔后特征评估,以确定与其个体强性FECs相关的因素.使用牛津纳米孔MinIon平台对两个研究农场的34只母羊进行了Nemabiome分析,目的是确定与羊群中母羊Nemabiome组成变化相关的因素。母羊FEC的最佳拟合模型结合了母羊身体状况评分,dag得分,品种,母羊年龄和产仔数之间的相互作用效应是固定因素。在每个农场上添加特定产仔数的母羊的平均FEC值进一步提高了模型拟合度,并减少了模型中农场之间的方差。Nemabiome分析显示,单个农场的羊群线虫多样性存在显着差异,在各自农场的母羊和双胎母羊中记录到的线虫多样性显着降低,而T.circincta在萨福克母羊和双胎母羊中的线虫比例明显更高(P<0.05)。我们的数据表明,可以利用通常记录的母羊特征来预测个别的围产期母羊FEC,一旦确定了特定的TST阈值,就可以用作羊场TST策略的指南,以在最小的牧场污染和最大的GIN避难所之间实现最佳平衡。这项研究是第一个利用牛津纳米孔MinIon测序来评估绵羊的线虫组,并在分子上评估羊群/羊群中反刍动物个体的线虫组,结果表明,线虫组组成在群内存在显着差异,这可能对TST和群管理策略产生影响。
Gastrointestinal nematodes (GINs) are a significant threat to the sustainability of global sheep production. Periparturient ewes play a key role in GIN epidemiology, with increased GIN faecal egg counts (FECs) in these ewes resulting in heavy pasture contamination that facilitates parasitic gastroenteritis in immunologically naïve lambs later during the grazing period. Traditionally, blanket anthelmintic treatment would suppress GIN egg outputs in these ewes and subsequent pasture contamination. However, farmers are now advised to implement targeted selective treatment (TST) to reduce anthelmintic use and subsequent anthelmintic resistance development, yet, there is currently limited evidence to determine optimal TST strategies in ewes. In this study, the characteristics of 226 ewes on seven Welsh farms were assessed postlambing to identify factors associated with their individual strongyle FECs using negative binomial mixed model analysis. Nemabiome analysis was conducted on 34 ewes across two study farms using the Oxford Nanopore MinIon platform with an aim of identifying factors associated with variations in ewe nemabiome composition within flocks. The best-fitted model of ewe FEC incorporated ewe body condition score, dag score, breed, and an interaction effect between ewe age and litter size as fixed factors. The addition of a mean FEC value for ewes of a specific litter size on each farm further improved model fit and reduced between-farm variance in the model. Nemabiome analysis revealed significant variation in within flock nemabiome diversity on individual farms, with significantly reduced nemabiome diversity recorded in ewes exhibiting dags and in twin-bearing ewes on respective farms, whilst T. circumcincta was present as a significantly higher proportion of the nemabiome in Suffolk ewes and twin bearing ewes (P < 0.05) in respective flocks. Our data demonstrate that commonly recorded ewe characteristics can be exploited to predict individual periparturient ewe FEC and subsequently may be used as a guide for TST strategies on sheep farms once specific TST thresholds are identified to deliver the optimal balance between minimal pasture contamination and maximal GIN refugia. This study is the first to utilise Oxford Nanopore MinIon sequencing to evaluate the nemabiome of sheep, and to molecularly assess the nemabiome of individual ruminants within a flock/herd, with results indicating that significant within flock variations in nemabiome composition which may have implications for TST and flock management strategies.