Heterophil/lymphocyte response of local Spanish breeds of laying hens to cold stress, heat stress, and water restriction.

Environmental challenges may adversely affect poultry production. Autochthonous breeds are particularly valuable in a climate change context because of adaptation to the local environment. The objective of the present study was to determine the impact of cold stress, water restriction, and heat stress on the stress response quantified by the heterophil to lymphocyte ratio (H/L) of ten local Spanish breeds of laying hens. Hens of these local breeds were consecutively subjected to three treatments: natural cold stress (2, 4, 6, 7, 9, and 13 °C), water restriction (with a duration of 2.5, 4.5, 7, 10, and 12 h, respectively), and natural heat stress (23, 26, 28, 30, 34, 38, 40, and 42 °C). During cold stress, H/L was higher at 9 and 13 °C than at 2, 4, and 6 °C, and higher at 9 °C than at 7 °C (P < 0.05). H/L values were similar during all water restriction levels. During heat stress, H/L was particularly elevated at temperatures higher than 40 °C (P < 0.05). Overall, Andaluza Azul, Andaluza Perdiz and Prat Codorniz showed lowest resilience to stress based on their H/L response, whereas Pardo de Leon, Villafranquina Roja, and Prat Leonada showed highest resilience.