Compositions are provided that contain sporulated coccidial oocysts, wherein the compositions are free of antibiotics and comprise formalin at a concentration sufficient to inhibit microbial growth for at least 12 months while maintaining oocyst viability. Methods of preparing such compositions are also provided.本發明提供含有孢子化球蟲卵囊之組合物,其中該等組合物不含抗生素且包含福馬林(formalin),該福馬林之濃度足以抑制微生物生長達至少12個月,同時維持卵囊活力。本發明亦提供製備該等組合物之方法。