Attempted Passive Immunization of Young Calves Against Eimeria bovis

SYNOPSIS. Two experiments attempted to produce passive immunity against Eimeria bovis coccidiosis in Holstein-Friesian calves. Immune serum concentrated by a freezing technique, or serum globulin obtained by a precipitating technique from immune calves, was injected intravenously or intraperitoneally into young calves. Four calves received concentrated immune serum injected intravenously on the day of oral inoculation with sporulated oocysts and again 7 and 14 days later. Four calves were given intravenous injections with some of the same serum on the 7th and 14th days after inoculation and 4 others were given a single similar injection with the same serum 14 days after inoculation.
Three calves in a second experiment received intraperitoneal injections of serum globulins in increasing amounts every 3 days for 2 weeks. The calves were then orally inoculated with sporulated oocysts one week after the last globulin injection. Some calves receiving immune serum had an anaphylactoid reaction characterized by increased respiration rate, dyspnea, coughing, and salivation; however, all affected calves recovered spontaneously within 2 hours. Calves receiving serum globulin had no reactions.
Coccidiosis developed in all of the calves in spite of the injection of immune serum or globulin presumed to carry the immune factor. There was no detectable difference in the rate of oocyst discharge or in clinical symptoms between treated and control calves; therefore, no evidence of passive immunity was observed.