Escherichia coli-associated porcine neonatal diarrhea: antibacterial activities of colostrum from genetically susceptible and resistant sows.

Antibacterial properties of colostrum from genetically resistant and susceptible sows in a herd in which only the susceptible sows had acquired natural immunity to K88-positive Escherichia coli have been investigated. Significant differences in antiadhesive and opsonic activities occurred. Colostrum from susceptible sows inhibited the binding of 125I-labeled K88 antigen to brush borders significantly better than did the colostrum from resistant dams. Colostrum from susceptible dams effected more efficient in vitro opsonic phagocytosis and killing of K88 E. coli than did colostrum from resistant dams. Differences in bactericidal properties of colostrum between the two groups of pigs were not significant. Fractionation of colostrum from susceptible dams by gel filtration and ion-exchange chromatography revealed that the fractions rich in immunoglobulin M had the highest opsonic activity, whereas those containing predominantly immunoglobulins G and A were of lower activity.