OBJECTIVE: To test the ability of oral vaccination or probiotic treatment with lactic acid-producing bacteria to protect calves from Cryptosporidium parvum infection under field conditions. ANIMALS: 134 Holstein calves born on a dairy farm where cryptosporidiosis was endemic. PROCEDURE: Calves were randomly assigned to 1 of 3 treatment groups at birth. Calves in the vaccine group received an oral dose of C parvum vaccine 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. All calves were monitored for diarrhea and fecal shedding of C parvum oocysts for 3 weeks. RESULTS: There were no significant differences in the incidence of diarrhea and oocyst shedding among the 3 groups. CONCLUSIONS: Neither vaccination 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 of these regimens. Further work is necessary to develop effective prophylaxis against C parvum under field conditions.
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Harp et al. (1996) studied this question.