Blood profile of japanese quail (Coturnix japonica) under thermal stress

In quail raising the limits of climatic variables such as temperature and relative humidity, affect the performance and welfare of these birds. The thermal comfort temperature for quails is between 18 and 22 degrees C and the discomfort can cause stress by changing circulating heterophils and lymphocytes and heterophil/lymphocyte ratio. The objective of this study was to establish the stress levels in quails during the production cycles with different temperatures through changes in WBC and the heterophil/lymphocyte ratio. This study was conducted in four production cycles of 200 Japanese quails (Coturnix japonica), during 22 days each one (referred as C1, C2, C3 and C4). Average temperatures were: 22.4 degrees C (C1), 25.5 degrees C (C2), 23.3 degrees C (C3) and 21.5 degrees C (C4). We collected blood samples from 80 quails in each cycle for determination of haematological parameters and values of the heterophil-lymphocyte ratio (H/L). The heterophil / lymphocyte ratio average was 1.695 for C1, 2.424 for C2, 1.8 for C3 and 1.29 for C4. Comparing this average among the four cycles is noted that the p value was less than 0.0001, except between the first and third periods, in which the p value was not significant. The heterophilia and lymphopenia verified and the increase in the heterophil/lymphocyte ratio in the cycle, coinciding with rising temperatures, beyond the limit of thermal comfort for these birds mainly in C2, is evidence that these birds were in heat stress and that the quails are highly susceptible birds to climate variations.