Within the commercial hatchery 10 chickens were culled for blood sampling directly out of the incubators, 10 were culled after the hatchery process was complete and a further 10 individuals were culled upon arrival to the animal housing facility in Linköping. 30 control birds were also killed for blood samples, to compare baseline CORT levels with the hatchery samples. 10 were culled after incubation, 10 after 15 minutes in home pen and the remaining 10 were culled when the hatchery birds arrived at the animal housing facility. Blood was collected from each chick by decapitation.

Blood samples were also take from 10 males and 10 females from each pen for sex hormone analysis at age 15 and 19 weeks.

All blood samples were collected using a microvette heparin coated tube which holds 200 µl of blood. The blood samples were stored on ice or in a refrigerator until ready for centrifugation in the lab. The plasma was separated from the blood samples and frozen in storage at -40C until the time of analysis using a corresponding ELISA test.