Kruger, LeonVan der Merwe, C.2022-07-252022-07-252021-11http://hdl.handle.net/11660/11780This paper reveals the efficacy of five anthelmintic products containing different active ingredients used to treat Haemonchus contortus infestation in 25 Dohne merino lambs in total divided into 5 groups. Faecal worm egg count test (FEC) data was used to determine the percentage efficiency of each anthelmintic. The efficacy of each anthelmintic product result from the level of resistance displayed by the H. contortus population on the Paradys experimental farm against the product, meaning the higher the level of resistance the lower the efficacy of the anthelmintic. Startect (derquantel + abamectin) proved to be the most effective with an efficacy of 99.35 % followed by Uni-Dose (trichlorfon) with an efficacy of 89.23 %. Ivomec (ivermectin) resulted in showing the highest level resistance and a negative efficacy of -131.83 % followed by Tramisol (levamizole) having an efficacy of 3.56 %. Prodose Orange (closantel + albendazole) had an efficacy of 30.94 %.enDepartment of Animal Sciences--University of the Free State, 2021OtherUniversity of the Free State