Abstract
An attempt was made to see if it was possible to produce antimicrobial activity in colostrum after killed Escherichia coli O111 vaccine had been given orally to expectant mothers. The colostral samples were used in vitro for the inhibition test immediately after the start of lactation. The colostrum from 7 of the 47 vaccine-treated mothers inhibited the growth of E. coli O111 compared with only one colostrum from 101 controls. No complication has occurred either in the vaccine-treated mothers or their suckling babies. The association between the presence of antimicrobial activity in the colostrum and the time of vaccine application was insignificant.