FIELD TESTING OF PROPHYLACTIC MEASURES AGAINST CRYPTOSPORIDIUM-PARVUMINFECTION IN CARVES IN A CALIFORNIA DAIRY-HERD

Objective-To test the ability of oral vaccination or probiotic treatme nt with lactic acid-producing bacteria to protect carves from Cryptosp oridium parvum infection under field conditions. Animals-134 Holstein calves born on a dairy farm where cryptosporidiosis was endemic. Proce dure-Calves were randomly assigned to 1 of 3 treatment groups at birth . Calves in the vaccine group received an oral dose of C parvum vaccin e within several hours of birth. Calves in the bacteria group received an oral dose of lactic acid-producing bacteria daily for the first 10 days after birth. Control calves were not treated. Air calves were mo nitored for diarrhea and fecal shedding of C parvum oocysts for 3 week s. Results-There were no significant differences in the incidence of d iarrhea and oocyst shedding among the 3 groups. Conclusions-Neither va ccination nor probiotic treatment was effective in preventing C parvum infection in calves under-field conditions. High numbers of C parvum in the environment may have overwhelmed any potential benefits oi thes e regimens. Further work is necessary to develop effective prophylaxis against C parvum under field conditions.