Antioxidant status, cytokine level, immunocompetence, Hsp70 mRNA expression, and selenium metabolism of goats fed higher selenium under heat stress conditions

Heat stress (HS) induces oxidative damage that imparts deleterious effects on production performance of livestock. Selenium (Se) is an essential ultra-trace mineral and a cofactor for selenoproteins (SeP) crucial for regulating antioxidant status of livestock. Therefore, a study was conducted to determine the dietary Se requirement under heat stress (HS) using twenty-eight non-producing female goats (around 1.5 years of age, with an average weight of 21.9 ± 1.32 kg). The goats were randomly divided into four groups (CON, CON_HS, T1_HS, and T2_HS), with seven animals per group. The CON group was fed basal diet with 351 ppb Se and maintained under thermo-neutral (TN) condition throughout the experimental period of 60 days, whereas goats in CON_HS, T1_HS, and T2_HS were fed on diet with 351, 1156, and 2018 ppb Se respectively under TN condition for initial 39 days and then exposed to HS during the last 21 days of the experimental period. Goats in the HS groups experienced moderate to severe HS. In CON_HS, blood hemoglobin was lower (p = 0.019), while serum alanine aminotransferase (p = 0.046) and aspartate aminotransferase (p = 0.03), creatinine (p = 0.004), cholesterol (p = 0.006), cortisol, malondialdehyde, pro-inflammatory cytokine (interlekin-1; p ≤ 0.001), were higher compared to T1_HS and T2_HS. The T1_HS and T2_HS groups had increased activities of serum antioxidant enzymes (glutathione peroxidase, catalase, and superoxide dismutase; p < 0.002), their component minerals (selenium, iron, and manganese and copper; p < 0.025), and levels of insulin (p ≤ 0.001), tri-iodothyronine (p = 0.040), and tetra-iodothyronine (p ≤ 0.001). Additionally, cell mediated- and humoral- immune response, and heat shock protein 70 expression were higher (p < 0.05) in T1_HS and T2_HS. Thus, it is concluded that 2018 ppb dietary Se is beneficial for ameliorating HS-induced negative effects on oxidative status, hormonal balance, cytokines profile, immunity, and Se metabolism in goats.