Impact of temperature humidity index (THI) on blood gas and electrolytes of dairy cows in late gestation

The study was carried out to assess the impact of heat stress on dairy cows in late gestation and their newborn calves. Study was conducted in two phases in crossbred cattle during last trimester of pregnancy, maintained in University Livestock Farm and Fodder Research Development Scheme, Mannuthy, KVASU. December to February with minimum THI was taken as season 1 and March to May with maximum THI as season 2 of the study. Microclimatic data in the animal shed was recorded three times at three days intervals. The ambient temperature, relative humidity and THI obtained during season 2 was significantly (p<0.01) higher than season 1 in both macro and microclimatic data. Partial pressure of carbon dioxide (pCO2 ) was low in season 2 but there was no significant difference in potassium (K+), sodium (Na+), bicarbonate (HCO3 - ) and partial pressure of oxygen (pO2 ) between the seasons. Keywords: Heat stress in cattle, THI, blood gases, electrolytes, late gestation