Feed Additives for Coccidiosis Prevention: Comparative Evaluation of the Efficacy of Diclazuril, Robenidine and Oregano Oil in Growing Rabbits Experimentally Infected With <i>Eimeria</i> spp.

The present study aimed to compare the efficacy of diclazuril and robenidine, used for decades to prevent rabbit coccidiosis, with oregano oil as a potential phytogenic alternative. Four compound feed variants were tested: one variant without additive for the control group (CG), a second supplemented with diclazuril (1 mg/kg; DG), a third with robenidine hydrochloride (66 mg/kg; RG) and a fourth added with oregano oil (75 mg/kg; OG). A total of 48 SPF rabbits aged 5 weeks were kept in groups of three animals. Four groups (12 rabbits) were assigned to each of the 4 dietary variants. At Day 10 after arrival, each animal was experimentally infected with 1300 sporulated oocysts (Eimeria media, Eimeria magna, Eimeria perforans, Eimeria flavescens and Eimeria coecicola) originating from German rabbit stocks. Absolute excreted oocyst numbers were determined, Eimeria species identified, and reproduction rates calculated. Feed and water intake, body weight gain and feed conversion were assessed in addition to excreted faecal weights and their dry matter content. In all groups, the experimental infection resulted in markedly reduced performance parameters, changed faecal consistencies and reduced faecal weights. None of the three feed additives significantly reduced Eimeria reproduction or improved zootechnical parameters and faecal quality compared to the control animals. The present study confirms for the first time the complete and simultaneous ineffectiveness of diclazuril and robenidine due to multiple resistance in rabbit Eimeria species. Oregano as a herbal alternative for the prevention of coccidiosis in rabbits is not scientifically justified.