Polyether ionophoric antibiotic having a unique tricyclic spiroketal ring system and an unsaturated 6-membered ring in the molecule. Produced by a strain of Streptomyces albus (FERM-P No. 419 and ATCC 21838). Production: Y. Miyazaki et al., JP Kokai 72 25392 (1972 to Kaken Chem.), C.A. 78, 41561 (1973). Structure: H. Kinashi et al., Tetrahedron Lett. 1973, 4955. Taxonomy, production, isolation and physicochemical and biological properties: Y. Miyazaki et al., J. Antibiot. 27, 814 (1974). Use as a coccidiostat: Y. Tanaka et al., DE 2253031; eidem, US 3857948 (1973, 1974 to Kaken Chem.). Anticoccidial efficacy: T. T. Migaki et al., Poult. Sci. 58, 1192 (1979). Total synthesis: Y. Kishi et al., Front. Chem., Plenary Keynote Lect. IUPAC Congr., 28th 1981, K. J. Laidler, Ed. (Pergamon, Oxford, 1982) pp 287-304; R. C. D. Brown, P. J. Kocienski, Synlett 1994, 415, 417. HPLC determn in animal feeds: M. R. LaPointe, H. Cohen, J. Assoc. Off. Anal. Chem. 71, 480 (1988).