Evaluation of efficacy of toltrazuril and diclazuril in the control of subclinical eimeriosis in weaned lambs

A field study was conducted to compare the effect of toltrazuril and diclazuril treatment against Eimeria infection in 142 naturally infected, weaned lambs aged 45-60 days. Lambs were divided into three groups of 48, 48 and 46 animals and treated with toltrazuril (20 mg/kg b.w.) and diclazuril (1 mg/kg b.w.). The last group of 46 lambs was left untreated as control. Oocyst faecal counts (OPG), Eimeria species and faeces consistency where assessed weekly from day 7 to day 63. In comparison with the control group, the OPG reduction on day 7 and 14 in toltrazuril-treated lambs was 99.1% and 97.4%, respectively, and 67% and 58% in lambs treated with diclazuril (p < 0.005). On day 21, the percent of OPG reduction was still significant in toltrazuril-treated lambs (76.3%, p < 0.05). Treatment with toltrazuril showed a decrease of Eimeria ahsata and E. crandallis oocysts at the time of maximum efficacy. The same effect was found in the diclazuril-treated group for E. ahsata only. No difference was found between the three groups regarding the consistency of the faeces (p > 0.05). Body weight gains were determined at the start and the end of the study and showed a significant increase in the toltrazuril-treated lambs (p < 0.001). These results suggested a greater efficacy of toltrazuril against subclinical eimeriosis in weaned lambs.