Directional selection for growth at two ambient temperatures in Coturnix coturnix japonica

Four lines of quail; random-selected, male-selected, female-selected and male- and female-selected lines, were subjected to 37 plus or minus 1-6 degrees C from 3 to 5 weeks of age while another four lines, similarly selected, were reared at room temperature (15 to 27 degrees C). Selection for increased growth was practised for two generations using ten females and five males as parents in each line. A significant interaction between time and temperature was observed in the third generation progeny; when exposed to heat stress, the stress-adapted lines showing a superior growth rate. A sex X temperature interaction was also observed and was due largely to the control females being more sensitive to stress than the males. A cumulative realised heritability estimate of 0-47 plus or minus 0-15 for 5-week body weight was obtained.