【作者】 范淳；

【导师】 陈代文； 余冰；

【作者基本信息】 四川农业大学 ， 动物营养与饲料科学， 2009， 硕士

【摘要】 本研究考察了日粮不同水平的无机硒(亚硒酸钠)和有机硒(酵母硒),对正常和应激状态下艾维茵肉仔鸡生产性能、甲状腺激素、抗氧化能力、组织硒含量等的影响,以揭示不同硒源对不同状态下肉仔鸡的添加效应;同时以亚硒酸钠为参比,在正常和应激状态下评定酵母硒的相对生物学效价,为不同硒源在肉鸡不同生产环境中的合理选择提供科学依据,也为有机硒产品的研发与应用提供理论依据。本研究包括两个试验:试验一不同来源和水平的硒对肉仔鸡生产性能、抗氧化能力及组织硒含量的影响采用2×5因子设计,在基础日粮中分别添加0、0.1、0.2、0.3和0.4 mg/kg的亚硒酸钠和酵母硒(以硒含量计)以考察对肉仔鸡生产性能、抗氧化能力、甲状腺激素和组织硒含量的影响。将216只14日龄健康的艾维茵肉仔鸡(预先经过2周的缺硒日粮饲喂),随机分配到9个处理中(0水平为共用),每处理3个重复,每重复8只鸡。正式试验为期4周,从15至42日龄。结果显示:(1)硒的添加有提高肉仔鸡日增重的趋势,显著改善了饲料转化效率,总体来看,适宜添加水平为0.1～0.2 mg/kg;(2)随着硒水平的提高,血清T3含量显著增加,T3/T4也有提高的趋势;(3)随着硒水平的提高,肉鸡的抗氧化能力明显增强,表现为GSH-Px、SOD、T-AOC的升高和MDA的下降,以0.3～0.4 mg/kg水平添加效果较好;(4)随着硒水平的提高,肉鸡血清及组织硒含量显著增加,以0.4mg/kg水平添加沉积量最大;(5)酵母硒在组织的硒沉积量上显著高于亚硒酸钠,而在其他指标上硒源间无显著差异。试验二不同硒源对应激肉仔鸡生产性能、抗氧化能力、组织硒含量的影响及酵母硒的生物学效价本试验旨在考察不同硒源对皮质酮诱导的应激肉仔鸡的添加效应,并评定正常和应激状态下酵母硒的相对生物学效价。选用240只艾维茵肉仔鸡,按2×3×2因子设计,包括2种硒源(亚硒酸钠或酵母硒),3个水平(0、0.1或0.4 mg/kg),2种状态(正常或应激),共10个处理(0水平为共用),每处理3个重复,每重复8只鸡。通过在日粮中添加20 mg/kg皮质酮以诱导应激,试验为期2周,从15至28日龄。结果表明:(1)皮质酮的添加,诱导了肉仔鸡的应激,引起氧化损伤,表现为丙二醛的显著增加;(2)随着硒水平的提高,应激肉鸡的饲料转化效率有所改善,添加0.4 mg/kg酵母硒效果较好;(3)随着硒水平的提高,应激肉鸡的血清皮质酮、尿酸浓度和肌酸激酶活性均降低,而T3、T3/T4及肝脏细胞色素C氧化酶有提高的趋势,表现出硒的抗应激效应;(4)随着硒水平的提高,应激肉鸡的抗氧化能力明显增强,血清和组织硒含量也显著增加;酵母硒的组织硒沉积量显著更高,而亚硒酸钠的血清GSH-Px活性明显高于酵母硒组,特别是在应激初期;(5)以亚硒酸钠为参比,若以组织硒含量为判定指标,正常状态下,酵母硒的平均生物学效价为132.1%,应激时则为141.6%;若以机体GSH-Px活性为判定指标,则平均生物学效价在正常和应激状态下分别为89.6%和95.7%。以上结果表明:(1)正常和应激状态下,随着硒添加水平的提高,肉仔鸡的生产性能均有所改善,抗氧化能力和组织硒含量也显著提高;硒源显著影响了组织硒含量,酵母硒有更多的硒沉积,但在机体的抗氧化方面硒源间无显著差异;(2)酵母硒在组织硒含量上的相对生物学效价高于亚硒酸钠,而在机体GSH-Px活性上不及亚硒酸钠;同时,应激状态下,酵母硒的生物学效价明显比正常时要高。更多还原

【Abstract】 The study was conducted to evaluate the effects of different levels of sodium selenite and yeast selenium on growth performance,thyroid hormone,antioxidant capacity and selenium content in tissues of Avian broiler chickens under normal and stress conditions in order to reveal the effectiveness and bioavailability of Yeast-Se relative to Na₂SeO₃ for broilers.The results will provide the scientific basis for a reasonable choice between different selenium sources at the different production environment,as well as for development and application of organic selenium product. This study included two trials:Trial 1 the effects of different sources and levels of selenium on performance, antioxidant ability and tissue selenium content of broiler chickens.A total of 216 Avian broiler chickens were used to investigate effects of sodium selenite or yeast selenium on performance,antioxidant ability,thyroid hormones and tissue selenium content.The broilers,which were fed the diet deficient in selenium for two weeks,were allocated to 9 treatments,each of which had 3 pens of 8 chickens per pen.The 9 dietary treatments were basal diet only and basal diet adding 0.1,0.2, 0.3 and 0.4 mg/kg selenium as Na₂SeO₃ or Yeast-Se,respectively.The trial lasted 4 weeks,from D15 to D42.The results showed that（1） supplementation with Se tended to increase ADG and significantly improved feed/gain ratio and optimal Se level for performance was 0.1-0.2 mg/kg.（2） As the Se level elevated,serum T3 concentration increased significantly and T3/T4 tended to increase.（3） As the Se level elevated, antioxidant ability of broilers enhanced significantly,reflected as increase of GSH-Px, SOD,T-AOC and decline in MDA.Optimal Se level for antioxidant capacity was 0.3-0.4 mg/kg.（4） As the Se level elevated,selenium content in serum and tissues of broilers increased significantly and Se deposition was highest at 0.4 mg/kg.（5） The broilers consuming Yeast-Se diets had higher Se deposition in tissue than Na₂SeO₃. But,there was no significant difference between selenium sources in other parameters.Trial 2 the effects of different sources of selenium on performance,antioxidant ability and tissue selenium content of broiler chickens under stress condition and bioavailability of Yeast-SeThis trial was conducted to investigate the effects of adding selenium on stressd broiler chickens and assess the relative bioavailability values of Yeast-Se for normal and stressed chickens.A total of 240 Avian broiler chickens,14 d of age,were allocated to 10 treatments by 2×3×2 factorial design,including two Se sources （sodium selenite or yeast selenium）,three levels（0,0.1,0.4 mg/kg,0 level shared by two sources） and two conditions（normal or stress induced by adding 20 mg/kg corticosterone in basal diet）,each of which had 3 pens of 8 chickens per pen.The trial lasted 2 weeks to 28 d of age.The results showed that（1） supplementation of corticosterone in diet induced physiological stress successfully,and then caused oxidative injury in chickens,reflected as the significant increase in malondialdehyde. （2） As the Se level elevated,feed conversion of stressed broilers was improved and the best effect was gained at 0.4 mg/kg Yeast-Se.（3） As the Se level elevated,the concentration of corticosterone and uric acid and creatine kinase activity decreased in serum,while T3,T3/T4 and cytochrome C oxidase of stressed broilers tended to be improved,indicating the anti-stress effects of selenium.（4） As the Se level elevated,the antioxidant ability and selenium content in serum and tissues of stressed broilers increased significantly.Yeast-Se had higher selenium deposition, but Na₂SeO₃ had higher GSH-Px activity in serum,especially in early phase of stress.（5） According to slope ratio assay,when sodium selenite was used as reference material,selenium content of serum,kidney,liver and breast muscle as assessment indexes,the average relative bioavailability of Yeast-Se was 132.1% under normal condition,and 141.6%under stress condition.However,when activity of GSH-Px in serum and liver were taken as assessment indexes,the average relative bioavailability of Yeast-Se was 89.6%and 95.7%,respectively.Above results indicated that（1） under normal or stress conditions,the high level of selenium improved performance,significantly increased antioxidant ability and selenium content in tissues of broiler chickens.Selenium sources significantly affected selenium content in tissue and Yeast-Se had more selenium deposition,but there was no difference in antioxidant ability in the body.（2） Yeast-Se had higher relative bioavailability value for tissue selenium content,but lower for GSH-Px activity than Na₂SeO₃.However,under stress condition,the bioavalability of Yeast-Se was higher than normal condition.更多还原