Effect of selenium yeast on diquat-induced oxidative damage in hens’ ovaries

<bold>Objective</bold> The residue of Dipyridinium pesticide（DQ）in plants or diet is easy to cause oxidative damage to animals.Based on the antioxidant function of selenium，the effects of dietary supplementation of selenium yeast（SeY）on DQ-induced oxidative damage in hens’ ovaries were investigated. <bold>Method</bold> In this experiment，sixty healthy 6-month-old Kangle yellow hens with similar body weight were randomly divided into control group（CON group），DQ-induced oxidative stress group（DQ group），SeY pre-treated DQ-induced oxidative stress group（SeY+DQ group）and SeY pre-treated group（SeY group）.The hens in control group and DQ group were fed a common commercial diet，and the hens in SeY+DQ group and SeY group were fed a common commercial diet supplemented with SeY（containing 0.5 milligram Se per kilogram diet）.After 14 days of per-feeding，hens in DQ group and SeY+DQ group were injected intraperitoneally at a dose of 15 mg/kg·BW DQ solution，and chickens in CON group and SeY group were injected intraperitoneally at an equal dose of 0.9% NaCl solution.After 4 days of feeding，ovarian tissue samples were collected.The changes of oxidative stress，apoptosis and reproductive performance in ovarian tissue of chickens in each group were detected by antioxidant function test Kit，HE staining，Western blot and qPCR experimental techniques. <bold>Result</bold> （1）Compared with CON group，the average daily gain，average daily laying rate and average daily feed intake of hens in DQ group were significantly decreased（<italic>P</italic>_DQ&lt;0.05）.The activities of antioxidant enzymes CAT and T-SOD and the expression levels of antioxidation-related genes <italic>Nrf2</italic>，<italic>HO-1</italic> and <italic>Gpx1</italic> in ovarian tissue of hens in DQ group were significantly decreased（<italic>P</italic>&lt;0.05），MDA concentration was significantly increased（<italic>P</italic>&lt;0.05），follicle development was inhibited，and apoptosis level was significantly increased（<italic>P</italic>&lt;0.05）.The expression of reproductive performance-related regulatory genes（<italic>ZP2</italic> and <italic>Wnt4</italic>）was inhibied（<italic>P</italic>&lt;0.05）.In SeY group，CAT activity was significantly increased（<italic>P</italic>&lt;0.05），MDA concentration was significantly decreased（<italic>P</italic>&lt;0.05），and the expression level of <italic>HO-1</italic> was significantly up-regulated（<italic>P</italic>&lt;0.05）.The development level of follicles was not significantly changed，but the number of follicles was increased.The expression levels of <italic>ZP2</italic> and <italic>Wnt4</italic> were significantly up-regulated（<italic>P</italic>&lt;0.05）.（2）Compared with DQ group，there was no significant change in hen production performance impairment caused by DQ in SeY+DQ group（P&gt;0.05），the activity of CAT and T-SOD were significantly increased（P&lt;0.05），and the expression levels of <italic>Nrf2</italic>，<italic>HO-1</italic> and <italic>Gpx1</italic> were all up-regulated（<italic>P</italic>&lt;0.05）.The concentration of MDA was significantly decreased（<italic>P</italic>&lt;0.05）.The development level of follicles was returned to normal.The expression levels of <italic>Bax</italic>，<italic>Caspase3</italic> and the ratio <italic>Bax</italic> to <italic>Bcl-2</italic> were all significantly down-regulated（<italic>P</italic>&lt;0.05）.The expression level of <italic>Bcl-2</italic> was significantly up-regulated（<italic>P</italic>&lt;0.05），and the expression levels of <italic>ZP2</italic> and <italic>Wnt4</italic> were also up-regulated（<italic>P</italic>&lt;0.05）. <bold>Conclusion</bold> DQ can induce oxidative stress in chicken ovarian tissue，increase the level of apoptosis，and then inhibit the expression of the regulatory genes related to follicle development and reproductive performance.Dietary SeY supplementation can effectively improve the antioxidant and anti-apoptotic ability of chicken ovarian tissue under DQ，and reduce the degree of oxidative damage of DQ to ovarian tissue.The results provide a theoretical basis for further exploring the method of SeY protecting the production and reproductive performance of female birds from oxidative damage.