Abstract
The study was carried out to investigate the effect of dietary selenium (Se) and vitamin E (VE) supplementation on mRNA level of heat shock proteins, selenoproteins, and antioxidant enzyme activities in the breast meat of broilers under summer heat stress conditions. A total of 200 male broilers (Ross 308) of 1 day age were randomly separated into 4 groups in a complete randomized design and were given a basal diet (Control, 0.08 mg Se/kg diet) or basal diet supplemented with VE (250 mg/kg VE), sodium selenite (0.2 mg/kg Se), or Se + VE (0.2 mg/kg Se + 250 mg/kg VE) to investigate the expression of key antioxidant and heat shock protein (HSP) genes under high temperature stress. Dietary Se, VE and Se + VE significantly enhanced the activities and mRNA levels of catalase as well as superoxide dismutase (SOD) but decreased the mRNA levels of HSP70 and HSP90. Se alone or combined with VE increased the concentration of selenoprotein P and selenoproteins mRNA level and decreased the expression of HSP60. In addition, Se and Se + VE significantly enhanced the glutathione peroxidase (GPx) activity and the expression of GPx1 and GPx4 in breast muscle tissues. It is noteworthy that all the treatments significantly decreased malondialdehyde (MDA) level in the breast meat. Overall results showed that Se in combination with VE has maximal effects to mitigate heat stress. Based on given results it can be recommended that Se + VE are a suitable dietary supplement for broilers to ameliorate the negative effects of summer heat stress conditions.
Highlights
Heat stress affects the performance of the birds (Gregory 2010)
Stress inducible proteins like HSP70 work as molecular chaperons that safe guard cells and organisms as they keep cellular proteins in a competent folding condition to prevent the aggregation of irreversible proteins and help in the refolding of proteins damaged by the stress (Gabriel et al 2001)
No any significant difference was observed between the groups Se and vitamin E (VE)
Summary
Previous studies showed that meat productivity decreased in chronic heat stress conditions (Hashizawa et al 2013). The heat stress increases mortality, decreases feed intake and feed conversion efficiency, reduces body weight gain low carcass weight, and decreases meat. Hyperthermia produces oxidative stress and increases the production of ROS (Robert et al 2017) which results in the induction of the expression of HSP70 (Zhang et al 2006). The major role of antioxidants is to reduce the free radicals and prevent the lipid peroxidation that protects cells from ROS (Nanari et al 2004; Grashorn, 2007). Low plasma concentration of antioxidant vitamins (C and E, and folic acid) and minerals (Se and Zn) are negatively correlated with high damage caused by oxidation in poultry reared under stress conditions (Sahin et al 2002)
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