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In order to
monitor the changes in heat dissipation through sweating and
panting, oxygen consumption, heat production, heat storage,
physiological responses (RR, RT and ST) and antioxidant
enzymes status, five heifers of Murrah buffaloes were
selected from herd and maintained under normal feeding and
management followed at the farm. The animals were exposed to
four exposure temperatures viz. 32, 35, 40°C with a constant
relative humidity of 50% and sham control at 8.00am in a
climatic chamber for three hours continuously. The pre
exposure heat loss through skin ranged from 5433.49 ± 371.18
to 5749.63 ± 327.53 KJ/ hr. The heat loss through skin
increased with the increase in climatic temperature (40°C).
The maximum heat loss (8584.11 ± 262.48 KJ/ hr) was observed
at III exposure conditions. The mean values of pre exposure
pulmonary heat loss ranged from 528.26 ± 35.56 to 542.79 ±
14.6KJ/ hr. The percent increase in pulmonary heat loss over
pre exposure values were greater at all the exposures
compared to heat loss through sweating. The pre exposure
oxygen consumption of heifers ranged from 1.38 ± 0.02 to
1.59 ± 0.01 lit/ min. The pre exposure values of oxygen
consumption increased after three hours of exposure at all
the exposure conditions. The levels of antioxidant enzymes
(super oxide dismutase and catalase) showed a linear
increasing trend with the increase in the temperature from
32 to 40°C in the climatic chamber. The sweating, panting,
oxygen consumption, physiological responses and antioxidant
enzymes levels increased significantly (P<0.01) during
different exposures, intervals of exposures and their
interactions. All the parameters also showed a significant
(P<0.01) positive relationship with the temperature humidity
index. The results of the study indicated that the heat
stress had an adverse impact on physiological status of
buffalo heifers. Therefore, buffalo heifers require a
protection from heat stress at higher temperature (40°C)
exposure for maintaining body temperature.
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