Genetic differences in susceptibility to ulcerative enteritis in Japanese quail

Six lines of Japanese quail were derived from a single foundation population. Four of the lines were selected on the basis of family mean three week body weight, two were unselected and all lines were randomly mated. Quail were housed in wire batteries during the brooding, rearing and laying periods. During the brooding period, hover temperature and floor space per chick were similar from line to line. For the rearing and laying periods, floor space per chick was approximately the same from line to line. During an outbreak of ulcerative enteritis (diagnosed on the basis of gross and histopathology) in generation 31 and again in generation 34, mortality ranged from zero for males of one control line to approximately 50 percent for females of one selected line. Analysis of variance showed that incidence of mortality differed significantly among lines and between sexes. Mortality was generally higher in selected than in control lines and in females than in males. It is suggested that susceptibility to ulcerative enteritis in quail may be a polygenically inherited trait and that the breeding which accompanied selection for body size may have made some loci homozygous for susceptibility alleles.