We evaluated the hematologic responses of 20 female buffaloes raised under full sun (group NS) and shade (group SG) at Belem, Para , Brazil. The animals in the SG group (n = 10) were maintained in paddocks under a silvopastoral system with Racosperma mangium, and the ones in the NS (n = 10), in paddocks with Brachiaria humidicola, with drinking water and mineral salt, but without access to shade. Air temperature (AT), relative air humidity (RH) and black global temperature (BGT) were measured for each treatment. Blood sampling for erythrogram and leukocyte count were undertaken at intervals of 14 days, and carried out at 1:00 p.m., during 2009. AT and black global temperature and humidity index (BGHI) were different (P < 0.05) throughout the year, and their highest values were observed in the NS group. During the rainier period, the SG group presented the highest values of leukocytes (P < 0.05), although in the transition and low rainy periods, the highest values were observed in the NS group. In the low rainy period, the erythrocytes count showed the highest values in the NS group. The highest levels of hemoglobin (P < 0.05) were observed during the transition and low rainy periods. Only hemoglobin presented a significant and negative (P < 0.05) correlation with RH. We concluded that the female Murrah buffaloes are subject to a hostile environment, and that the low rainy period is the most favorable for causing heat stress.
hematology; buffaloes; bioclimatology
