The Effect of Social Stress on Resistance to Infection with Escherichia coli or Mycoplasma gallisepticum

FOR many years the results of our experimental work with Escherichia coli seemed to lack the consistency that we desired. At times the same inoculum given to different groups of birds resulted in varying numbers of birds with pericarditis. Healthy uninoculated birds were raised in many batteries in an isolated building. When needed, birds were placed in the experimental cages from one or more batteries. Frequently birds from several battery sources remained in small experimental cages for from 1–7 days before being exposed to E. coli. Davis and Reed (1958) infected two groups of mice with Trickinella spiralis. The individuals in one group were isolated in individual cages while the others were allowed to fight in small groups for 4 hrs. daily. Isolated mice had fewer mature trichina than those which were allowed to fight. Newcomer (1958) found that chickens which were stressed by shaking or restraint had an…