All experimental procedures involving broiler chickens in this study were conducted at the Animal Nutrition Unit of the Universitat Autonoma de Barcelona, after approval by the Ethical Committee on Animal Experimentation.
All broiler chickens used were 1 d-old male Ross 308 chicks vaccinated for infectious bronchitis and infectious bursal disease.
Feed and water were provided ad libitum and temperature was controlled throughout the experiments following the Ross 308 broiler manual (/http://en.aviagen.com/ross-308S).