Effect of thermal stress in physiological, hormonal and haematological parameters of Tharparkar calves in comparison with that of Karan Fries

Abstract

The present investigation was undertaken to study the effect of thermal stress on physiological, haematological and hormonal parameters in Tharparkar and Karan Fries calves. The animals of both breeds were divided into two groups. Group I of each breed was kept in the natural climatic conditions; whereas group II of each breed was exposed to temperatures 10, 25 & 44⁰C in the climatic chamber for 4 hours.  Blood samples were collected before exposure and at the end of 4 h exposure. The physiological responses; respiration rate (RR), heart rate (HR), rectal temperature (RT), skin temperature (ST); haematological profile, hormone levels in the plasma were estimated. The physiological responses (RR, HR, RT, and ST) increased significantly in both breeds at 44⁰C compared to 10⁰C and 25⁰C. Significant increase was also recorded in RBC, haematocrit and haemoglobin, whereas no significant changes were observed in TLC and DLC (lymphocyte, monocyte, and granulocyte). At 44⁰C, prolactin and cortisol levels increased significantly in both breeds whereas no significant differences were observed in GH concentration. The increase in physiological responses, RBC, haematocrit, haemoglobin was higher in Karan Fries than Tharparkar. The breed differences in hormone levels also signified that Tharparkar was more thermotolerant than Karan Fries cattle. The significantly higher deviations in physiological, haematological, hormonal levels reported in Karan Fries than Tharparkar in the present study may serve as indicators of distress level in Karan Fries calves during thermal stress.