High dietary vitamin E and selenium improves feed intake and weight gain of finisher lambs and maintains redox homeostasis under hot conditions

• We elucidated role of dietary vitamin E and selenium in finisher lambs.
• Vitamin E and selenium supplementation improved average daily feed intake.
• Vitamin E and selenium supplementation increased average daily gain.
• Oxidative status of the lambs finished under heat stress normalized with antioxidants.

The present study was conducted to elucidate the role of dietary vitamin E (Vit E) and selenium (Se) on the oxidative status of lambs exposed to short term hot conditions during finishing. Forty-eight lambs (crossbred; 42 ± 2 kg body weight, 7 mo age) were allocated to one of three groups (16 per group) and fed 3 different doses of Vit E and Se. A standard finisher pellet ration (17% CP and 12.57 MJ ME/kg DM) was used as the basis of treatment diets. The doses of Vit E and Se for control (CON), moderate (MOD), and supranutritional (SUP) diets were 28, 130, 228 mg/kg DM as α- tocopherol acetate and 0.16, 0.66, 1.16 mg Se as SelPlex™ kg/DM, respectively. After 4 weeks feeding in individual pens, including 1 week of adaptation, lambs were moved to metabolism cages for 1 week and allocated to one of 2 heat regimes (8 per feeding group): thermoneutral (TN) (18–21 °C and 40–50% relative humidity) or heat stress (HS) (28–40 °C and 30–40% relative humidity) conditions. Dietary Vit E and Se supplementation increased average daily feed intake (P = 0.009) and average daily gain (P = 0.057) linearly (CON to SUP) during the 3 week finisher period before thermal treatments were applied. During thermal treatment, HS elevated (P < 0.001) both respiration rate (RR) and rectal temperature (RT). However, there were reductions in both RR (P = 0.05) and RT (P = 0.08) in lambs fed SUP levels of Vit E and Se. The concentration of plasma reactive oxygen metabolites (ROM) increased (P < 0.001) under HS, but were reduced by the SUP diet (117CARR U) as compared to CON (128CARR U). The concentration of plasma advanced oxidation protein products (AOPP) were increased (P < 0.001) during HS. Again, lambs fed the SUP diet had 35% lower (P = 0.005) AOPP levels than maximum levels in CON lambs when exposed to heat. Both RR and RT of lambs finished under HS were normalized after 14 h in lairage under TN conditions. Taken together, these data indicate that high levels (SUP) of dietary Vit E and Se improve average daily feed intake and average daily gain, and maintain oxidative balance in finisher lambs exposed to a heat stress challenge.