Genetic Resistance to Brucellosis in Swine

In the course of investigations on the epidemiology and course of contagious abortion in swine due to Brucella suis, two sows and a possibly related boar could not be infected—as determined by the agglutination test—by administering the organism by way of mouth. In addition, it was not found possible to infect the boar by subcutaneous inoculation with the strain of Brucella used to vaccinate cattle. Although these were grade stock and their pedigrees unknown, they were out of stock that originated in the University herd, and there was evidence that they were related to each other. Since the possibility of an hereditary resistance presented itself, a breeding program was initiated to determine if such resistance could be transmitted to their progeny. This paper is a progress report on these investigations. A preliminary report (Cameron, Hughes and Gregory, 1940) and a report on the bacteriology (Cameron, Gregory and Hughes, 1941) have been published, but are reviewed briefly in this paper.