A comparative study on effect of heat stress on physiological and cellular responses of crossbred cattle and riverine buffalo in subtropical region of India.

Abstract

The study was carried out to compare the in vitro and in vivo heat shock responses of cattle and buffaloes. The expression of heat responsive genes (HSP70 and HSF family) were studied in vitro in peripheral blood mononuclear cells (PBMCs) of cattle and buffalo. In vivo observations on animals were carried out to investigate the physiological responses of cattle and buffalo at different THI over a period of 14months. The study indicated that onset and severity of heat stress at different THI varied significantly between cattle and buffalo. Rectal temperature (RT) showed a significant (p < 0.05) increase at THI 67 in buffaloes and at THI 68 in cattle. Significant (p < 0.01) differences in RT between the species were observed at THI 71, 72, and 73. Respiration rate (RR) significantly (p < 0.05) increased at THI 70 in both the species and significant (p < 0.05) differences in RR were observed between the species at THI 65, 68, 69, and 74. THI had significant (p < 0.05) effect on blood glucose and blood electrolytes of the species with increased levels at higher THI. Serum AST and ALT levels showed less pronounced changes over increasing THI. Heat stress-associated expressions of HSP 70 genes followed temporal changes with incremental THI. The expression of HSPA8 was consistent at lower THI whereas upregulation of HSPA1A and HSPA1L was evident at higher THI. The study concludes that changes in physiological parameters such as RT and RR occur in a phasic pattern in both species and onset of heat stress was early in buffalo as compared to cattle.