Attempted transmission of Sarcocystis bovicanis from cows to calves via colostrum.

Sixteen pregnant cows were divided into four equal groups. Groups 1 and 2 were uninoculated controls; Groups 3 and 4 received 60,000 and 120,000 S. bovicanis sporocysts per os, respectively, about 30 days before expected parturition. Stained smears of colostrum from each quarter of the udder of each cow were examined microscopically for zoites. As a bioassay for infectious zoites in colostrum of acutely infected cows, colostrum from infected Group 4 cows was fed to calves from control Group 1 cows. Calves in Groups 2 and 3 received colostrum from their dams. Calves in Group 1 received colostrum from uninoculated normal cows. All calves were killed at 61 to 68 days of age and their tissues examined microscopically for Sarcocystis cysts. Because zoites were not found in colostrum smears and cysts were not found in calf tissues, it was concluded that lactogenic transmission of S. bovicanis did not occur.