Efficacy of oral immunization with Cryptosporidium parvum in a colostrum-deprived neonatal calf challenge model

A major cause of reduced performance and death in neonatal dairy calves is diarrhea, regardless of cause. Cryptosporidium parvum is a protozoal pathogen that is frequently associated with diarrhea in neonatal dairy calves. Virtually all dairy calves that are raised on commercial operations are infected with C. parvum by 3 weeks of age. Conventional colostrum does not contain protective levels of antibodies against C. parvum, and therapeutic agents with efficacy for prevention of C. parvum oocyst excretion or reduction of clinical severity of diarrhea are lacking. The objective of this study was to determine the efficacy of an inactivated C. parvum preparation as an oral immunogen in a colostrum-deprived calf challenge model.