Maintenance energy of buffaloes in different environmental temperatures.

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Three buffalo-cows and three Holstein cows were maintained in a climatized laboratory(Zootron, NIAI) for 7days at constant temperature of 30ﾟC(60%RH,12L12D) and fed every 3hours(constant condition). Then, they were fasted for 5days in the room where13EA\ : the air temperature fluctuated diurnally between 25 and 35ﾟC(average 30ﾟC, 60%RH, 12L12D, fluctuating condition). Under the fluctuating condition, heat productions in buffaloes were significantly lower than those in Holsteins. On the contraly, no s13EA\ : ignificant difference was observed between the two species in the constant temperature. when air temperature increased from 25ﾟC(0 : 00) to 35ﾟC(12 : 00), the respiration rate, respiratory volume and heat production in Holsteins increased almost sim13EA\ : ultaneously, while the rectal temperature in this species was almost constant. In the other hand, respiration rate, respiratory volume and heat production in buffaloes did not increased first 6hours, duing which rectal temperature increased associat13EA\ : ed with the increase of air temperature. These results indicate that buffaloes maintain their respiration at a fairly low level by storing heat within their body mass when the air temperature increases in the morning. This thermolability in buffaloe13EA\ : s may contribute to the energy saving characteristics of this animal by refraining the respiratory exercise in the course of diurnal changes of air temperature.