Effects of Long-term Heat Exposure on Adaptive Mechanism of Blood Acid-base in Buffalo Calves

Abstract

In order to investigate the mechanism of adaptation to long-term heat stress, six female buffalo calves of about 7 to 8 months age, were exposed to the cool-comfort environment (THI 65) for 21 days to obtain normal values of blood acid-base. An adaptive response of acid-base regulation was determined to long term (21 days) exposure of buffalo calves to hot-dry (THI 80) and hothumid (THI 84) conditions. Higher rectal temperature and respiratory rate was recorded under hot-humid exposure compared to hot-dry. Significant reduction in the rectal temperature and respiratory rate on day 21 of hot-dry exposure indicated early thermal adaptation compared to hot-humid. Decreasing rectal temperature and respiratory rate from day 1 to 21 was associated with concurrent decrease in blood pH and pCO 2 . Increased plasma chloride concentration with low base excess in blood and in extracellular fluid suggested compensatory response to respiratory alkalosis. Reduced fractional excretion of sodium with increased fractional excretion of potassium and urine flow rate indicated renal adaptive response to heat stress.

Thermoregulatory and adaptive responses of adult buffaloes (Bubalus bubalis) during hyperthermia: Physiological, behavioral, and metabolic approach

“…The significant rise in RT during HS (37.54°C vs. 38.01, 38.77°C) indicate increasing heat load on the buffaloes and inability to normally dissipate the accumulating heat, consequently raising the body temperature. Significant increase in RT (p<0.001) was also seen in heat-exposed buffalo calves as compared to cool comfortable conditions [11]. Similarly, higher RTs (°C) were also seen in heat-exposed Tharparkar (38.74±0.11 vs. 38.96±0.05) and Karan Fries heifers (38.84±0.06 vs. 39.19±0.24) than at thermoneutral treatments validating our findings [12].…”

Adaptive capability as indicated by endocrine and biochemical responses of Malpura ewes subjected to combined stresses (thermal and nutritional) in a semi-arid tropical environment

“…A negative correlation between plasma protein and elevated environmental temperature has been reported in some studies (Habeeb 1987;Sejian et al 2008a). The biological significance of thermal-stress reducing proteins is to support hepatic gluconeogenesis by glucocorticoids to increase glucose levels to allow the animal to cope with thermal stress (Kamiya et al 2006;Korde et al 2007). The decrease in plasma protein may be due to dilution of plasma proteins and the decrease in protein synthesis as a result of depression of anabolic hormone secretion (El-Masry and Habeeb 1989).…”

Impact of heat stress and hypercapnia on physiological, hematological, and behavioral profile of Tharparkar and Karan Fries heifers

“…The probable reason of reduction in BE might be due to low oxygen tension (PO 2 ) which might have increased anaerobic glycolysis to cause excess production of lactic acid. Korde et al [39] also reported low BE in buffalo calves in heat stress condition and suggested that it might be a compensatory response to respiratory alkalosis. West et al [40] also observed low BE in heat-stressed dairy cows and suggested that the reduction in BE might be due to either increased respiratory rate/panting under heat stress, which eliminated CO 2 in excess and caused decreased PCO 2 as well as carbonic acid, or it might be due to decrease in the non-bicarbonate buffer system, particularly Hb which resulted in decreased levels of buffer in blood.…”