Differences in adaptation to tropical weather between buffaloes and cattle

Twenty buffaloes and twenty Vietnamese yellow cattle from peri-urban Hue city were kept indoor and used for measurement of effect of environmental temperature (T o ) and humidity (H%). The T o and H% were recorded by thermo-hygrometers for temperature and humidity index (THI) measurement. Breathing rate was observed by moving rate of diaphragm, heart beat rhythms was calculated by stethoscope around 3 to 4 ribs and body T o tested by 42 o C thermo-meters in animal rectums. The results showed that the T o in the area studied varied widely during the day and when T o increased H% often decreased. During the study period the average T o changed from 24 o C in February to 39 o C in May. The H% varied from 57 to 86. The environmental T o and H% had very little effect on body T o for both types of animals (37 o C to 39 o C) but there were changes in heart beat from 42 to 45 in cattle but from 44 to 57 in buffaloes. In warmest period with high H% (THI 83) breathing rates in cattle varied from 18 to 21 while in buffaloes from 20 to 35 and in May it increased to 50. At the warmest time of the day the heart beat in cattle were 42 while in buffaloes 57. The breathing rate in cattle only increased when ambient T o was above 39 degrees. The results clearly showed that buffaloes were easily stressed when T o and H% increased. Buffaloes need water and swamps to help to avoid heat stress while indigenous cattle are much better adapted to high environmental T o and H%.