Effects Of Dietary Selenium On Reproductive Function And GPxs Expression In Testes Of Goats

The purposes of this study were to optimize the dietary selenium contents, and to investigate mechanisms of selenium on reproductive function in goat. Different doses of both sodium selenite and Se-enriched yeast were added into diet of ducks and does to study the effect of Se on reproductive hormones, thyroid hormone, immune function, antioxidase activities in serum and seminal plasma, the sperm ultrastructure, Semen quality, conception rate. The effects of maternal Se contents the expressions of GPxs and cell cycle key genes in offspring lambs testes were investigated. The results were shown as followings:1. Selenium could stimulate FT3secretion, increase body’s metabolism. At the day30th, serum FT3concentration in the group of2.0mg/kg Se-enriched yeast was significantly higher than that in control group (P<0.05); At the day60th, serum FT3concentration in Se-enriched yeast group was significantly higher than that in control group (P<0.05). This showed the efficiency of accelerating FT3secretion was greater in Se-enriched yeast group than that in sodium selenite group.2. Selenium was supplemented in diet, buck serum IgA, IgM, IgG, IL-2, IL-6and IL-10content was increased, respectively, and the body immune function was improved. IgA, IL-2and IL-6content in the groups of2.0mg/kg Se-enriched yeast and sodium selenite, IgA, IgM, IL-6and IL-10content in the group of1.0mg/kg sodium selenite, IL-6and IL-10content in the group of1.0mg/kg Se-enriched yeast, and IgM and IL-6content in the group of0.5mg/kg sodium selenite were all higher than that in control group (P<0.05); while the content of WBC, LYM, MON and ratio of LYM and MON in buck blood in the group of2.0mg/kg sodium selenite was respectively lower than that in control group (P<0.05), and the ratio of LYM and MON in buck blood in the group of1.0mg/kg sodium selenite was respectively lower than that in control group (P<0.05).3. Selenium was supplemented in diet, serum GPxs activity, serum and seminal T-AOC content in bucks were increased dramatically (P<0.01), meanwhile, serum and seminal SOD content and seminal GPxs activities were also increased significantly (P<0.05); while serum OH-content was decreased remarkably (P<0.01), and Seminal OH-content was decreased significantly (P<0.05), thereby the body’s antioxidant capacity was improved. There were dose-effect relationships between selenium concentrations and serum/seminal enzymatic activities (SOD content and GPxs activities), and between selenium concentrations and T-AOC and OH-content. Compared with the groups of1.0mg/kg and0.5mg/kg selenium (Se-enriched yeast or sodium selenite), the content of OH-in serum and seminal plasma in group2.0mg/kg selenium (Se-enriched yeast or sodium selenite) was increased, but GPxs activity in serum, and SOD activity and T-AOC content in seminal plasma were all decreased.4. When adding selenium concentration in diet ranged from0.5mg/kg to1.0mg/kg originated from different selenium sources, there was no significant difference in spermatozoon mitochondrial structure; when there appeared dietary selenium deficiency (Control) in diet, there occurred abnormal sperm mitochondrial structure, incomplete plasma membrane, reduced chromatin condensation degree, even cavitation phenomenon. Spermatozoon mitochondria also occurred abnormal in the group of2.0mg/kg sodium selenite. Added0.5mg/kg and1.0mg/kg of Se-enriched yeast or sodium selenite in diet, the sperm motility, spermatozoon acrosome integrity and does conception rate were increased highly (P<0.05), but the spermatozoon deformity rate was decreased significantly (P<0.05). The efficiency of Se-enriched yeast was better than that of sodium selenite. When supplemented Se-enriched yeast or sodium selenite up to2.0mg/kg in diet, the spermatozoon motility, acrosome integrity and does conception rate became significantly lower (P<0.05), therefore the spermatozoon abnormality was significantly higher (P<0.05).5. The effects of selenium on serum reproductive hormone concentrations and thyroid hormone concentration in pregnant dose were related to different kinds of hormones, pregnant stage, selenium source and additive amount. When the additive amount of selenium was0.5mg/kg-1.0mg/kg in diet, E2secretion in early pregnant period and FSH and P secretion in late pregnant period could be promoted; and serum FT3concentration during pregnancy was elevated, but the concentrations of serum T4and FT4was reduced during late pregnancy, the reproductive functions and metabolic status in doess were improved. The efficiency of0.5mg/kg-1.0mg/kg selenium additive was the best. When the additive amount of selenium was more than1.0mg/kg, the hormonal secretion concentrations became declined. Within the appropriate additive concentration (0.5mg/kg-1.0mg/kg), the efficiency of Se-enriched yeast on acceleration of hormonal secretion was better than that of sodium selenite.6. The maternal selenium could significantly improve the expression levels of GPx1, GPx3and GPx4mRNA, thereby GPxs activities were accelerated, and the antioxidant capacity of testicles of offspring lambs was improved. The expression abundances of GPxl, GPx3and GPx4mRNA were the biggest in the group of1.0mg/kg Se-enriched yeast. High selenium or selenium deficiency down-regulated the expression of the key genes, Cyclin B1and P34cdc2gene in cell cycle signal transduction, therefore the testicular spermatogenesis cycle was influenced.In summary, the optimal selenium concentration in diets was0.5mg/kg-1.0mg/kg selenium (Se-enriched yeast or0.5mg/kg sodium selenite) for bucks, the optimal selenium concentration in diets was0.5mg/kg～1.0mg/kg selenium (Se-enriched yeast) for pregnant does.