【作者】 白雪；

【导师】 李飞； 张兆才；

【作者基本信息】 兰州大学 ， 农业·畜牧（专业学位）， 2021， 硕士

【摘要】 硒是反刍动物的必需微量元素,在维持正常生理功能和生长发育过程中发挥重要作用。硒可通过谷胱甘肽过氧化物酶(Glutathione peroxidase,GSH-Px)调节机体抗氧化能力,还可通过合成多种硒蛋白或直接增强机体免疫细胞功能的方式提高机体的免疫能力。此外,缺硒时补充硒也可提高反刍动物的生产性能。动物生产上使用的常见硒源多为亚硒酸钠、酵母硒和纳米硒等,葡萄糖硒尚未广泛应用且鲜有研究报道,其在湖羊体内的吸收代谢和组织内沉积规律也尚不清楚。因此本研究旨在对比和评估不同硒源(酵母硒、葡萄糖硒和亚硒酸钠)的不同添加水平对育肥湖羊血清抗氧化性能、组织富硒规律、肉品质及生产性能的影响,为科学生产富硒动物性产品、开发葡萄糖硒的应用潜力奠定理论基础。试验一饲粮不同硒源对育肥湖羊组织富硒规律及肉品质的影响为评价葡萄糖硒在湖羊生产中的应用潜力,比较不同硒源对于育肥湖羊抗氧化性能、组织硒沉积、生产性能等多方面的作用差异,本试验挑选32只4月龄湖羊公羔(32.20±3.31 kg)作为试验对象,随机分为4组,每组8只羊,分别饲喂基础日粮(0.54 mg Se/kg DM,CON),基础日粮中添加酵母硒(0.8 mg Se/kg,0.8SY),基础日粮中添加葡萄糖硒(0.8 mg Se/kg,0.8SG),基础日粮中添加亚硒酸钠(0.8 mg Se/kg,0.8SS)。整个试验包括14 d预饲期和42 d正试期。结果表明:与CON组相比,添加不同硒源对湖羊生长性能无显著影响,但可提高血清抗氧化水平。添加SG和SS可分别延长肌肉货架期7.7 h和5.9 h,并显著上调GPX1的m RNA表达水平。添加有机硒(SG、SY)显著提高湖羊背最长肌、肾脏和毛发中的硒沉积量,上调GPX3和GPX4基因表达水平。由此可见,在湖羊生产中SG与SY作用相似,证明SG可作为新型硒源用于湖羊生产中。试验二饲粮葡萄糖硒添加水平对育肥湖羊组织富硒规律及肉品质的影响本试验通过设置三个葡萄糖硒添加剂量,研究育肥湖羊抗氧化、组织硒沉积量、肉品质及货架期等方面的变化情况,筛选葡萄糖硒的适宜添加剂量,为湖羊生产中合理应用葡萄糖硒奠定理论基础。挑选24只4月龄湖羊公羔(32.13±3.58kg)作为试验对象,随机分为3组,每组8只羊,分别饲喂基础日粮(0.54 mg Se/kg DM,CON),基础日粮中添加不同水平的葡萄糖硒(0.8 mg Se/kg,0.8SG;1.2mg Se/kg,1.2SG)。整个试验包括14 d预饲期和42 d正试期。研究发现:与CON相比,不同水平的SG均可显著提高1-21 d湖羊日增重、背最长肌硒含量、上调GPX1和GPX3基因m RNA的表达量,降低血清MDA含量。0.8 mg/kg水平的SG可延长肌肉货架期6.8 h并显著降低肌肉MDA含量。上述结果表明,SG的两种添加剂量均可发挥积极作用,但从成本与效果的双重考虑下0.8 mg/kg SG添加剂量更适宜在湖羊生产中应用。试验三低添加水平下亚硒酸钠和酵母硒对育肥湖羊组织富硒规律及肉品质的影响前期研究结果表明,添加0.8 mg/kg的酵母硒与亚硒酸钠均可使湖羊肌肉硒含量达到富硒标准以上,但亚硒酸钠有可能对动物产生毒性。为探索更节约成本及更为安全的富硒羊肉生产方式,本试验挑选24只4月龄湖羊公羔(31.99±3.60kg)作为试验对象,随机分为3组,每组8只羊,分别饲喂基础日粮(0.54 mg Se/kg DM,CON),基础日粮中添加低水平酵母硒和亚硒酸钠(0.4 mg Se/kg,0.4SY,0.4SS)。整个试验包括14 d预饲期和42 d正试期。结果显示:添加0.4 mg/kg SY和SS对育肥湖羊的生产性能无显著影响,但可显著提高血清T-AOC,降低血清中MDA含量,增加背最长肌和毛发中的硒沉积量。SY可显著提高肝脏、肾脏和心脏的硒沉积量,但抑制GPX2在肌肉中的表达;SS可显著上调GPX3的m RNA表达量,但有缩短肌肉货架期、增加肌肉中MDA含量的作用。由此可见,0.4 mg/kg的SY和SS均可用于富硒羊肉生产,但SY在湖羊产品保存与富硒效果方面作用更佳。综上所述,本研究结果表明:(1)0.8 mg/kg添加水平下,葡萄糖硒与酵母硒作用相似,可作为新型硒源用于湖羊生产。(2)在湖羊生产中葡萄糖硒0.8 mg/kg的添加水平较1.2 mg/kg效果更佳且节约成本。(3)0.4 mg/kg添加水平下,酵母硒与亚硒酸钠均可生产富硒羊肉,但酵母硒较亚硒酸钠更有利于富硒动物性产品的生产与保存。以上结论为不同硒源尤其是葡萄糖硒在湖羊生产中的应用及适宜添加剂量的选择提供了有力的数据支撑,并为下一步葡萄糖硒的深入研究奠定理论基础。更多还原

【Abstract】 Selenium is an essential trace element for ruminants that plays an important role in maintaining normal physiological functions and development.Selenium can regulate the antioxidant function of the body through GSH-Px.Selenium also could synthesize a variety of selenoproteins or directly enhance the immune cell function to improve the immune capacity of ruminants.Besides,supplementation of selenium during selenium deficiency can also improve the performance of ruminants.Currently,sodium selenite,selenium-enriched yeast and nano-selenium are the common Se source used as a supplement in ruminant feeds.Selenized glucose has not been widely used in animal production at present,and few correlation studies were reported.The regulation of absorption,metabolism and tissue selenium-enrich ability in ruminants is still unclear.Therefore,the purpose of the present investigation was to compare the effects of different selenium sources and levels on serum antioxidant performance,tissue selenium-enrich ability,meat quality and growth performance in fattening Hu sheep and further study on the application feasibility of using different selenium sources in the production of selenium-enriched animal products in the future.Experiment 1: Effects of dietary supplementation with different selenium sources on tissue selenium-enrich regularity and meat quality in fattening Hu sheep.Thirty-two male Hu lambs(32.13±3.58 kg)were random Ly assigned to four treatment groups with eight lambs.These four treatments received the same basal diet which was either Se unsupplemented(0.54 mg Se/kg DM,CON)or supplemented with selenium-enriched yeast(0.8 mg Se/kg DM,0.8SY)or selenized glucose(0.8mg Se/kg DM,0.8SG)or sodium selenite(0.8 mg Se/kg DM,0.8SS).After the adamption for 7 d,the formal period will last for 42 d continously.The results showed that compared with CON,performance and slaughter performance of Hu sheep were not affected by different selenium sources,but improves serum antioxidant status effectively.SG and SS can extend muscle shelf-life by 7.7 h and 5.9 h and enhance the GPX1 gene expression.Organic selenium(SG、SY)significantly raised the Se content in the longissimus dorsi,kidney and hair and enhance the GPX3 and GPX4 gene expression.It can be seen that SG and SY have similar effects in Hu sheep production,which proves that SG can be used as a new selenium source in Hu sheep production.Experiment 2: Effects of dietary supplementation with selenized glucose levels on tissue selenium-enrich regularity and meat quality in fattening Hu sheep.Twenty-four male Hu lambs(32.13±3.58 kg)were random Ly assigned to three treatment groups with eight lambs.These three treatments received the same basal diet which was either Se unsupplemented(0.54 mg Se/kg DM,CON)or supplemented with different levels selenized glucose(0.8 mg Se/kg DM,0.8SG;1.2 mg Se/kg DM,1.2SG).After the adamption for 7 d,the formal period will last for 42 d continously.The study found that compared with CON,different SG levels can significantly raise1-21 d ADG,reduce MDA content,increase the Se content in the longissimus dorsi and upregulate the GPX1 and GPX3 gene expression.However,0.8 mg/kg SG can extend muscle shelf-life by 6.8 h and significantly reduce MDA content in muscle.The above results show that the two dosages of SG can play a positive role,but from the dual consideration of cost and effects,the dosage of 0.8 mg/kg SG is more suitable for application in Hu sheep production.Experiment 3: Effects of dietary supplementation with selenium-enriched yeast and sodium selenite on tissue selenium-enrich regularity and meat quality in fattening Hu sheep.Twenty-four male Hu lambs(31.99±3.60 kg)were random Ly assigned to three treatment groups with eight lambs.These three treatments received the same basal diet which was either Se unsupplemented(0.54 mg Se/kg DM,CON)or supplemented with low level selenium-enriched yeast(0.4 mg Se/kg DM,0.4SY)or low level sodium selenite(0.4 mg Se/kg DM,0.4SS).After the adamption for 7 d,the formal period will last for 42 d continously.The results showed that growth performance of Hu sheep was not affected by SY and SS,but can improve serum T-AOC and MDA content effectively and raise the Se content in the longissimus dorsi and hair.SY can raise the Se concentrations in the liver,kidney and heart,but it suppressed the GPX2 gene expression in muscle.SS can enhance the GPX3 gene expression,but it has the effects of shortening the shelf-life of muscle and increasing the content of MDA in muscle.It can be seen that both SY and SS at 0.4 mg/kg can be used in the production of seleniumenriched mutton,but SY is more conducive to the production and preservation of selenium-enriched Hu sheep products.In summary,three conclusions can be drawn from this study:(1)At the level of 0.8mg/kg,SG has similar effects with SY,and can be used as a new selenium source for Hu sheep production.(2)The level of 0.8 mg/kg for SG is more appropriate than the level of 1.2 mg/kg in the production of Hu sheep.(3)At the level of 0.4 mg/kg,both SY and SS can produce selenium-enriched mutton,but SY is more conducive to the production and preservation of animal products than SS.The above conclusions provide strong data support for the application of different selenium sources in the production of Hu sheep and the selection of appropriate dosages,especially SG,and lay a theoretical foundation for the further research of SG.更多还原