Effects of a short‐term supranutritional selenium supplementation on redox balance, physiology and insulin‐related metabolism in heat‐stressed pigs
Selenium is incorporated into glutathione peroxidase (GPX) which is an antioxidant enzyme. The current nutrient requirements of swine (National Research Council 2012) recommend 0.2 ppm Se for growing pigs under thermoneutral conditions. However, as a nutritional strategy to reduce HS, it is unknown whether a short‐term supplementation with supranutritional amounts of Se before and during a heat event can alleviate physiology and oxidative stress in heat‐stressed pigs, as it does in sheep (Chauhan, Celi, Leury, Clarke, & Dunshea, 2014; Chauhan, Celi, Leury, & Dunshea, 2015). However, pigs are more insulin sensitive than ruminants (Dunshea & D'Souza, 2003; Pethick, Harper, & Dunshea, 2005), and a cautionary note is that supranutritional Se supplementation (0.5–3.0 ppm) can adversely impact on insulin homoeostasis in pigs (Liu et al., 2012; Pinto et al., 2012) possibly by inhibiting the expression and function of the proteins participating in the insulin signalling. Therefore, the aims of the study were to investigate the effects of dietary Se supplementation as a means of mitigating the physiological responses and oxidative stress, and to explore its role in insulin‐related metabolism in pigs exposed to HS. Our primary hypothesis was that supplementation with 1.0 ppm Se for 2 weeks before and during HS can mitigate physiological responses and oxidative stress in the heat‐stressed pigs with a secondary hypothesis that an alleviation of oxidative stress may normalize insulin action and lipid mobilization.