Assessing periparturient ewe characteristics and nemabiome composition to guide targeted selective treatment for sustainable gastrointestinal nematodes control in sheep.

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.

Farmer decision-making and risk perceptions towards outwintering cattle.

Increasing financial pressures has led farmers to manage cattle outside for the winter months. In temperate areas the environmental risks of outwintering cattle are exacerbated by cooler and wetter weather and identifying how farmers perceive these risks is essential to understanding how potential hazards could be mitigated. A series of workshops were conducted with cattle producers in England and Wales to understand their perceptions of the risks, their decision-making with respect to outwintering and their options for mitigating these risks. A range of risks were identified, but emphasis was placed on environmentally-related risks, such as soil damage, and on social risks, such as public perception of their treatment of the animals. The uncertainties due to the weather were highlighted as the most unmanageable risk. Another significant barrier to mitigating environmental impacts emerged from the lack of options towards choosing appropriate fields in which to conduct outwintering. We argue that the farmer-led nature of outwintering and the development of a wide range of systems is evidence of outwintering being a systems-innovation. We conclude that there is a role for Government intervention through the provision of information which clarifies cross-compliance breaches, but also encourages farmer-led innovation to develop more responsive outwintering systems.