Effects of Dietary Selenium, Vitamin E, and Their Combination on Growth, Serum Metabolites, and Antioxidant Defense System in Skeletal Muscle of Broilers Under Heat Stress

Abstract

This experiment was conducted to evaluate the effects of dietary vitamin E, selenium (Se), and a combination of the two, on the performance, serum metabolites and oxidative stability of skeletal muscle of broilers during heat stress. The broilers raised in either a thermoneutral (23.9°C constant) or heat stress (23.9°C to 37°C cycling) environment were assigned to 6 dietary treatments (0, 0.5, or 1 mg/kg Se; 125 and 250 mg/kg vitamin E; or 0.5 mg/kg Se plus 125 mg/kg vitamin E) from 1 to 49 days of age. At the end of the experiment, blood samples were collected from chicks, the chicks sacrificed, and pectoralis superficialis muscle was used for measurement of malondialdehyde (MDA) concentration and enzyme activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD). The heat-stressed chicks consumed less feed, gained less weight, and had higher feed conversion ratio when compared to thermoneutral chicks (P<0.05). Serum concentrations of iron (Fe) and zinc (Zn) were decreased by heat stress (P<0.05), whereas the serum concentrations of copper (Cu), glucose, and uric acid were significantly increased under heat stress (P<0.05). The chicks that received supplemental of vitamin E exhibited significantly higher serum concentrations of Zn (P<0.05) and significantly lower concentrations of Cu, glucose, and uric acid (P<0.05) when exposed to heat stress. Dietary Se also caused a significant decrease in serum glucose, uric acid, and Cu concentrations of heat-stressed broilers (P<0.05), but had no significant effect on Zn concentration (P>0.05). The GPx activity remained relatively constant (P>0.05), though SOD activity and MDA levels in skeletal muscle were enhanced on exposure to heat stress (P<0.05). The heat-stressed chicks that received the combined supplementary level of vitamin E and Se had the lowest concentration of MDA and the highest activity of SOD in the skeletal muscle (P<0.05). Dietary Se also caused a significant increase in enzyme activity of GPx in the skeletal muscle (P<0.05). These results indicate that the derangement of blood parameters and oxidative stability in broilers under heat stress are improved by supplemental vitamin E and Se.

Antioxidant Systems in Poultry Biology: Superoxide Dismutase

“…On exposure to chronic heat stress, GSH-Px activity remained relatively constant, though a temperaturedependent elevation in Cu,Zn-SOD activity was observed in skeletal muscle of broiler chickens [118]. Chicken exposure to heat stress increased SOD activity and MDA levels in skeletal muscle and vitamin E or vitamin E+Se dietary supplementation further enhanced SOD activity in muscles in heat-stressed birds [119]. In broiler chickens, plasma activity of SOD was increased, whereas GSH-Px was suppressed by heat stress (32 ± 1°C).…”

Selenium – a fascinating antioxidant of protective properties

“…21 The research more and more often includes selenoorganic compounds -either naturally occurring forms or newly synthesized substances, e.g., selenomethionine, naphthalimide-based selenocyanates, 2-(5-selenocyanatopentyl)-benzo[de]isoquinoline-1,3-dione, diphenyl diselenide, selenofuranoside, p-methoxyldiphenyl diselenide, selenocyanates, and diphenylmethyl selenocyanate. [4][5][6]9,16,17,19,20,[22][23][24][25][26] The results regarding the comparison of inorganic and organic compounds are not fully consistent, although the newest studies usually reveal plasma urea and plasma creatinine ↑; kidney vitamin C, GSH, GST, GPx, GR, CAT, δ-ALA-D ↓ p-methoxyl-diphenyl diselenide 50 mg/kg or 100 mg/kg, orally 6 days lower dose: plasma urea (±); plasma creatinine (0); kidney GSH, GST, GPx, GR, δ-ALA-D (±); kidney vitamin C, CAT (+) higher dose: plasma urea and plasma creatinine (±), kidney GSH, GST, GPx, GR, vitamin C, CAT (+) kidney δ-ALA-D (±) none ↓ -decrease; ↑ -increase; (+) -full protection; (±) -partial protection; (0) -lack of protection; GST -glutathione S-transferase; GPx -glutathione peroxidase; CAT -catalase; SOD -superoxide dismutase; GSH -reduced glutathione; TBARS -thiobarbituric acid-reactive substances; GR -glutathione reductase; δ-ALA-D -δ-aminolevulinic dehydratase..…”

“…2 The most important of them are the antioxidant enzymes -glutathione peroxidase and thioredoxin reductase, as well as selenoprotein P, responsible for the storage and transport of selenium. [3][4][5][6] Selenium supplementation has been proved to be protective against a very wide range of harmful factors, both chemical, such as drugs exerting severe side effects, heavy metals, carcinogens, mycotoxins, or pesticides, and physical, such as heat stress or magnetic fields. However, the narrow range between therapeutic and toxic doses of selenium, as well as the dependence of its effect on the applied form, dose and method of treatment, make the choice of the most effective supplement a very complex issue.…”

Selenium in poultry nutrition: a review

“…Se shows a clearly positive effect on the quality or stability of poultry meat. Oxidative stability in broilers under heat stress is improved by supplemental vitamin E and Se (Harsini et al 2012).…”