Comparative Effects of Different Forms of Dietary Supplemental Selenium in Hot Environment-induced Endoplasmic Reticulum Stress in Pigs.

Background: Dietary selenium (Se) supplementation shows protective effects against heat stress in animals, though further research is needed to fully understand its underlying processes.

Objective: This study aimed to compare the effects of three forms of dietary supplemental Se on biochemical, physiological, and production responses in heat-stressed pigs.

Methods: Forty pigs [(Large White × Landrace) ×Duroc], female, 2.5-month old, 35 ± 1.0 kg body weight)were divided into 4 groups (n = 10), and fed an Se-deficient basal diet (BD, Se˂ 0.05 mg/kg) or the BD + sodium selenite (SeNa), seleno-yeasts (SeY), or 2-hydroxy-4-methylselenobutanoic acid (SeO) at 0.3 mg Se/kg, respectively, for 3 months in the hot and humid summer of Wuhan, China. Growth performance, plasma and tissue Se content, selenoprotein expression, ER stress markers, and muscle quality were analyzed.

Results: Compared to BD, all Se-supplemented diets improved feed utilization efficiency, with SeY and SeO exhibiting greater effects (7.89% and 11.28%, respectively) than SeNa (5.12%; P < 0.05). Additionally, SeY and SeO supplementation significantly reduced drip loss in longissimus dorsi (LD) muscle by 25.94% and 27.19%, respectively, relative to BD (P < 0.05). All three Se-supplemented diets enhanced plasma antioxidative capacity and the conversion of tetraiodothyronine (T4) into triiodothyronine (T3). Compared with BD, the protein levels of ER stress markers ATF4, ATF6, CHOP, GRP78, and P-eIF2α/eIF2α in SeY and SeO diets were reduced by 49.44% and 42.18% (P<0.05), 54.73% and 25.85% (P<0.05), 4.37% and 29.06% (P<0.05), 64.43% and 65.20% (P<0.01), and 19.27% and 44.18% (P<0.05), respectively.

Conclusions: Dietary supplemental Se protected growing pigs against ER stress induced by environmental heat and humid. All three Se -supplemented diets improved the heat stress response, with organic forms (SeO and SeY) demonstrating relative advantages over SeNa in terms of feed utilization efficiency, pork quality, muscle fiber type composition, and glycolytic metabolism.