The influence of colostral leukocytes on the course of an experimental Escherichia coli infection and serum antibodies in neonatal calves.

Three hours post natum, 20 calves were orally infected with 10(9) colony forming units of an enteropathogenic E. coli. Immediately after infection and on 2 days subsequent, ten of the calves (COL-) received cell-deprived pooled colostrum and the other ten (COL+) pooled colostrum supplemented with colostral cells. The COL+ calves excreted significantly less bacteria of the infectious strain with their faeces in the first week after infection and reached the lower limit of detectability earlier than the COL- calves. Colostral leukocytes obtained from cows which developed clinical mastitis (n = 2), showed a marked reduction in the number of shed bacteria. The concentration of IgA and IgM specific antibodies against E. coli in the serum of the COL+ calves was significantly higher in the early postnatal period than in the serum of the COL- calves and remained at a slightly higher level throughout the whole investigative period. In addition to humoral substances of the colostrum, colostral leukocytes obviously contribute to the passive immunity and resistance of the newborn calf. The quality and quantity of the leukocytes seem to be of crucial importance to their efficiency.