Current approaches to the immunological control of enteric E. coli infections in pig herds concentrate on the provision of passive immunity for the neonate by multiple parenteral vaccination of the sow to stimulate colostral antibody production. Little account is taken of the kinetics of the animals' natural immune response. In particular the potential of the gut as a target organ for immunization has largely been ignored in practical disease control. A new approach to the problem, which combines oral with parenteral vaccination, stimulates a colostral antibody response closely mimicking a sow's natural response to infections and comparison between this and classical parenteral vaccination, using an acute E. coli infection model, demonstrated the greater protective efficacy conferred by the new protocol. The widespread use of this method of vaccination has been continuously monitored, using production parameters most relevant to the farming industry. From this evaluation of user experience and results of trials conducted in various locations, a new perspective is emerging which indicates the vaccine has a wider spectrum of biological activity than was expected. Production, health and environmental benefits are arising which could not have been predicted from a model merely concerned with the control of alimentary E. coli infection.