The targeted use of multispecies swards to manage parasites and promote livestock health and welfare

Chemical anthelmintics are not as effective as they once were due to the development of anthelmintic resistance (AR) which is becoming a widespread issue in the UK and Ireland. Multispecies swards (MSS), which contain plant secondary metabolites (PSMs), have been reported to reduce parasite burdens in sheep and cattle, hence protecting bodyweight, compared to grazing on perennial ryegrass (PRG) dominated swards. <br><br>This thesis investigates the practical implementation of MSS and targeted selective treatment (TST) to mitigate parasite burdens in sheep and cattle and reduce anthelmintic usage, prolonging anthelmintic efficacy.

Chapter one reviews the benefits, limitations, and strategic timing of alternative strategies to optimise impacts on parasites and animal performance. The progressing AR situation in the UK was assessed in chapter two, investigating changes on sheep farms over five years. Results showed increased multidrug and multi-species resistance, highlighting the need for effective alternative control strategies.