Mechanism Of Oxidative Damage Induced By Stress In Broilers

Three experiments were conducted in this study to discuss mechanism of oxidative damage induced by stress in broilers by mensurating antioxidative enzyme activities, antioxidant capacity, and oxidative damage of protein, fattiness, and DNA. We begin this research from three levers: overall level (plasma), organizational level (skeletal muscle), and cellular level (mitochondria).In experiment 1, to probe into mechanism of oxidative damage induced by stress in broilers by injecting DSP, thirty-six 16-day-old male Arbor Acres chickens were assigned randomly to three groups and injected subcutaneously with DSP or physiological saline (2.6 mg/kg BW) for 3 days. Three treatments were DSP, sham control and Pair-fed control, respectively. Mitochondrion was isolated from skeletal muscle of broilers. Activities of mitochondrial respiratory chain complexes,antioxidative enzyme activities in mitochondria and skeletal muscle, and content of MDA and protein carbonyl was measured by UV spectrophotometry. Activities of respiratory chain complexes and antioxidative enzyme in mitochondria was lower in DSP treatment in comparison with the control, whereas activities of CAT and SOD in plasma and formation of protein carbonyl and MDA was higher in DSP treatment.In experiment 2, we worked over mechanism of oxidative damage resulting in DSP and different diet level disposal. 150 male broilers of 1d were assigned randomly into two groups. One group fed with high-energy feed, another group fed with basic ration. As broilers in 14-day-old, we chose twenty-four broilers from two groups, respectively. Two days later, half of each group was injected subcutaneously with DSP (2.6 mg/kg BW), the other were injected subcutaneously with physiological saline with the same cubage for 3 days. 8-OHdG was measured by microplate reader. Fatty acid composition was analyzed using gas chromatography. Allantoin was measured by liquid chromatography. Activities of mitochondrial respiratory chain complexes and antioxidative enzymes, and content of MDA and protein carbonyl were measured by UV spectrophotometry. Mitochondrion was isolated from skeletal muscle of broilers. The results showed that broilers which fed with basic ration and injected with DSP had higher levels of uric acid, allantoin, protein carbonyl, MDA and 8-OHdG, as well as lower levels of PUFA and PUFA/SFA in skeletal, and the ability to inhibit hydroxyl radicals in plasma and skeletal in comparison with high-energy feed broilers and control, respectively. DSP disposal make for dysfunction of respiratory chain complexes and antioxidative enzymes, while high-energy feed may put back this phenomenon into suspension.In experiment 3, broilers were exposed to heat stress (32°C) to determine the effect of heat stress on relationships between mitochondrial function and oxidative damage. Twenty-four 35-day-old Male Arbor Acres chickens were distributed randomly into two groups. One group exposed to 32°C for 7 days, another group exposed to 24°C for 7 days as control. Mitochondrion was isolated from skeletal muscle of broilers. The results showed that the broilers which were exposed to high ambient temperature bring on dysfunction of respiratory chain complexes and antioxidative enzymes in comparison with control. Exposure to high temperature induced a significant elevation of formation of uric acid, allantoin, protein carbonyl, MDA and 8-OHdG, as well as reduction of T-AOC in plasma and the ability to inhibit hydroxyl radicals in plasma and skeletal.Taken together, results of this study showed an imbalance between oxidation and antioxidant system, lower mitochondrial function,and higher oxidative damage in chickens after injected DSP or exposed to high temperature, high-energy feed may ameliorate above points which was induced by injecting DSP.