Detection of moderate anthelmintic resistance in Clostantel and Macrocyclic lactone in organized central sheep breeding farm of Haryana, India

: This study was performed to evaluate the efficacy of currently used anthelmintics in organized central breeding sheep farm (CSBF) in Hisar, Haryana using faecal egg count reduction test (FECRT). A total of 60 sheep were chosen for this study and divided equally into four groups. Sheep were tested with closantel (@10mg/kg body weight) and two derivatives of macrocyclic lactone, moxidectin and doramectin (@0.2mg/kg body weight) while the control group did not receive any treatment. Sheep were naturally infected with gastro-intestinal nematodes and having EPG of faeces more than 150 counts before treatment were selected. Rectal faecal samples were collected on zero (pre-treatment) and 14th day (post-treatment) from animals of all groups and EPG of faeces were carried out by modified McMaster technique. In FECRT, reduction of faecal egg count (FEC) of less than 95%, indicate anthelmintic resistance (AR) in one or more nematode genera for the given anthelmintic. Per cent of FEC on 14 th day revealed that closantel, moxidectin and doramectin had 64%, 69% and 76% efficacy, respectively. Coprocultures from pre- and post-treated sheep revealed predominance Haemonchus contortus larvae. The result indicated development of moderate anthelmintic resistance against three anthelmintics, leading to change of anthelminthic drugs and regular monitoring for possible anthelmintic resistance in the