Seasonal alterations in the expression of inflammatory cytokines and cortisol concentrations in periparturient Sahiwal cows. Issue 8 (14th September 2021) - Grewal, Sonika
ABSTRACT: Heat stress during the transition period of dairy cows disturbs the homeostasis of their physiology and ultimately their health and production. Our objective was to study the seasonal variations of plasma cortisol levels and the expression of inflammatory cytokines in the peripheral blood mononuclear cells (PBMC) of 12 periparturient Sahiwal cows. Blood samples were obtained at weekly intervals from three weeks prepartum to three weeks postpartum during the winter (Temperature–humidity index, THI = 59.7) and summer (THI = 81.5) seasons. Gene expression study of pro-inflammatory (IL-1β, IL-6, and TNF-α) and anti-inflammatory (IL-10) cytokines was done by RT-PCR and plasma cortisol by sandwich ELISA. The plasma concentration of cortisol and the relative mRNA expression of various inflammatory cytokines in PBMC were higher ( p < 0.01) in the summer compared to winter season irrespective of the days of the transition period. Highest levels of cortisol and greater expression of pro-inflammatory cytokines were recorded on the day of calving in both seasons. Our study showed a higher inflammatory response, immune disturbance and greater levels of the stress hormone (cortisol) during the summer season, particularly on the day of calving.