Effect of heat stress and herbal products supplementation on the immune response related gene expression patterns in Kenguri ewes

Abstract

The study was conducted to establish the impact of heat stress as well as the herbal products supplementation on the expression patterns of immune response related genes in indigenous Kenguri ewes. A sixty days study was carried out in a climate-controlled environment by using 24 adult female Kenguri sheep. The study animals were randomly grouped into four with six animals each, viz., C (n = 6; Control; standard diet), HS (n = 6; Heat Stress; standard diet), CS (n = 6; Control Supplement; standard diet +herbal powder), and HSS (n = 6; Heat Stress Supplement; standard diet + herbal powder). The temperature humidity index (THI) recorded clearly indicated that the HS and HSS group ewes were exposed to severe heat stress while C and CS group ewes were exposed to thermoneutral condition. Further, heat stress increased plasma cortisol concentration while the herbal supplements reduced cortisol concentration (14.72 vs 11.16 ng/ml for HS and HSS, respectively, P < 0.01). Likewise, heat stress (P < 0.05) reduced the expression patterns of Interleukin-2 (IL-2), IL-18, Tumor necrosis factor alpha (TNF-α), Interferon beta (IFN-β), Interferon gamma (IFN-γ), superoxide dismutase (SOD) and glutathione peroxidase (GP_X). However, heat stress (P < 0.05) upregulated IL-6 expression. Therefore, all these cytokines can serve as biomarkers for quantifying heat stress on the immune response in Kenguri ewes. Further, the results also established that the herbal supplementation reduced the heat stress induced increased cortisol concentration and IL-6 levels (at day 60), in addition to recovering heat stress induced reduced levels of IL-2, TNF-α, IFN-γ and SOD to normal range. Thus, the herbal supplements used in this study brought beneficial effects in relieving the heat stress in Kenguri ewes.