【作者】 罗绪刚； 李素芬； 刘彬； 卜友泉； 邝霞； 余顺祥；

【Author】 Luo Xugang,Li Sufen,Liu Bin,Bu Youquan,et al. Institute of Animal Sciences,Chinese Acalemy of Agricultural Sciences,Beijing 100094,China

【机构】 中国农业科学院畜牧研究所； 河北科技师范学院；

【摘要】 目的通过两个试验研究确定心肌细胞线粒体中MnSOD的基因表达指标是否能更快、更敏感、更恒定地监测出肉仔鸡对不同形态锰源间生物学利用性的差异。方法试验(一)将546只商品代1日龄AA肉公鸡按4×4两因子安排的完全随机设计分为13个处理组,每组6个重复笼,分别饲喂不添加锰的食用玉米-豆粕型基础饲粮(对照组)或以无机硫酸锰、弱络合强度的蛋氨酸锰E、中等络合强度的复合氨基酸锰B及强络合强度的复合氨基酸锰C形式添加0、60、120、180mg/kg锰的试验饲粮,试验期21天。21日龄每个重复笼选取3只与平均体重相近的鸡屠宰,立即取出心脏、左侧腿跖骨,分析组织锰浓度、心肌细胞线粒体中MnSOD活性及其基因表达。试验(二)将270只商品代1日龄AA肉公鸡随机分为5个处理组,每组6个重复笼,分别饲喂不添加锰的食用玉米-豆粕型基础饲粮(对照组)及分别在对照组饲粮中添加120mg/kg锰的4种锰源试验饲粮。分别于第7、14、21日龄用与试验一目同的方法进行屠宰、组织样品的采集与制备及分析。结果试验(一)中21日龄肉鸡的跖骨灰锰含量、心肌锰含量和心肌细胞线粒体中MnSOD活性均受到饲粮添加锰水平的显著影响(P=0.0001),根据这三项指标与饲粮添加锰进食量的多元线性回归斜率比法进行计算,不同络合强度有机锰源间及有机锰源与无机锰源间均无显著差异,而21日龄肉鸡心肌细胞线粒体中MnSODmRNA水平受到添加锰源(P<0.10)和锰水平(P=0.0001)的显著影响,以心肌细胞线粒体中MnSODmRNA水平为评价指标,弱、中等和强络合强度有机锰源相对于硫酸锰(如设为100%)的生物学利用率分别为99%、133%和113%。其中中等络合强度Mn+AA B的相对生物学利用率明显高于硫酸锰和弱、强络合强度有机锰源(P<0.05)。试验(二)中饲粮添加中等络合强度Mn-AA B组鸡7日龄时心肌细胞线粒体中MnSOD mRNA水平就明显高于添加硫酸锰组和弱络合强度的Mn-Met E组(P<0.02),且在14日及21日龄恒定高于其它添加锰源组(P<0.05),而跖骨灰锰含量和心肌细胞线粒体中MnSOD活性等指标则明显不如MnSOD基因表达指标敏感。结论饲粮锰在转录水平上显著影响心肌细胞线粒体中MnSOD的基因表达;心肌细胞线粒体中MnSODmRNA水平早在雏鸡出壳后7天即可比其酶活性等所有其它指标更快、更敏感、更恒定地监测出肉鸡对不同形态锰源间生物学利用性的差异;有机锰源的络合强度与其对肉鸡的生物学利用率间有密切相关,中等络合强度有机锰源的相对生物学利用率明显最高;采用基因表达这一功能性指标,可以大大缩短试验期,减少试验动物数量,因而是未来研究锰源对鸡生物学活性的新方法 。更多还原

【Abstract】 Objective Two experiments were conducted to determine whether heart manganese containing superoxide dismutase(MnSOD) gene expression could detect the differences in bioavailabilities of Mn sources more quickly, sensitively and constantly than other indices.Methods In experiment 1,a total of 546 day-old commercial male Arbor Acres(AA) broilers were randomly assign to each of thirteen treatments with six cage replicates according to a completely randomized design involving a 4×4 factorial arrangement.Each group of binds was fed Mn-unsupplemented corn-soybean meal basal diets(Control) or basal diets supplemented with 60,120 or 180 mg/kg Mn as either Mn sulfate,Mn-Met E, Mn-AA B or Mn-AA C for 21days.At 21 day of age,three birds from each cage were selected according to average bodyweight of the cage and killed.Heart and left leg were excised immediately.Mn concentratfans in tissues,MnSOD activity and gene expression of MnSOD in heart were analyzed.In experiment 2,two hundreds and seventy day-old AA commercial male broilers were randomly allotted to one of five treatments with six cage replicates in a completely randomized design,and fed a Mn-unsupplenented com-soybean meal basal diet(Control) or the basal diet supplemented with 120mg/ kg Mn as each of the four Mn sources in experiment 1 for 21 days.The methods in experiment 1 were used to select and slaughter birds from each cage on the 7th,14th or 21th day.The tissues were collected and analyzed as well. Results(1) In experiment 1,ash Mn content,heart Mn content,and MnSOD activity in heart mitochondria on the 21th day were affected(P = 0.0001) by dietary added Mn level.Based on slope ratios from multiple linear regressions of these three indices on dietary aided Mn intake,the relative bioavailabilities of organic Mn sources did not differ from that of MnS04(P>0.14).Heart MoSOD mRNA level on the 21th day was affected by both Mn source(P<0.10) and Mn level(P= 0.0001).Based on slope ratios from the multiple linear regression of heart MnSOD mRNA level on dietary aided Mn intake,if 100%was set for Mn sulfate,the relative bioavailabilities of organic Mn sources with weak, moderate,and strong chelation strengths were 99 0%,132 3%and 112.7%,respectively.The organic Mn source with the moderate chelation strength was more available(P<0.05) than Mn sulfate and organic Mn sources with the weak or strong chelation strengths;(2) In experiment 2,the seven day- old chicks fed on the diet supplemented with the organic Mn source with the moderate chelation strength showed a higher(P<0.02) MnSOD mRNA level than those fed on the diets supplemented with Mn sulfate and the organic Mn source with the weak chelation strength,and the same tendency was observed on the 14 day or 21 day(P<0.05).Ash Mn content and heart MnSOD activity were less sensitive in detecting the differences among Mn sources in bioavailability than MnSOD mRNA level.Conclusion The results indicate that dietary Mn significantly affected heart MnSOD gene express fan pretranslationally,and heart MnSOD mRNA level as early as on the 7th day could detect differences in bioavailabilities of Mn sources more quickly,sensitively and constantly than all other indices.There was a close correlativity between chelatfan strengths of these organic Mn sources and their relative bioavailabilities for broilers,in which the organic Mn source with the moderate chelation strength was the most available. The estimation of relative bioavailabilities of Mn sources based on heart MnSOD mRNA level could request a shorter time of experimental period and smaller number of animals,and thus could be a new method for a quick and effective assessment in bioassays of Mn sources for broilers.更多还原