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

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 alpha- tocopherol acetate and 0.16, 0.66, 1.16 mg Se as SelPlex (TM) 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 degrees C and 40-50% relative humidity) or heat stress (HS) (28-40 degrees 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 totheat. Both RR and RT of lambs finished under HS were normalized after 14h 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. Crown Copyright (C) 2016 Published by Elsevier B.V. All rights reserved.