The impact of the chromium supplementation on insulin signalling pathway in different tissues and milk yield in dairy cows

Thirty days before expected time of parturition, 20 Holstein cows were divided into ?Cr and +Cr groups. From day 25 before parturition (BP ) up to day 30 after parturition (AP ), +Cr cows received 10 mg of Cr (chromium‐enriched yeast) daily. Muscle and adipose tissue samples were taken at days ?30, ?10, +7 and +10 related to parturition, when body condition score (BCS ) was also determined. Hepatic tissue samples were taken at days ?10 and +7. Tissue samples were used for determination of the insulin signalling pathway protein expressions. Intravenous glucose tolerance test (IVGTT ) was performed at days ?28, ?7, +10 and +30. Milk yield was recorded during first 14 weeks AP . Milk composition was obtained at days 7 and 28 AP . At day 10 BP , protein content of β ‐subunit of insulin receptor (IR β ) was significantly higher (p ? 0.05) in muscle, and phosphorylation of insulin receptor substrate 1 at serine 307 (pIRS ‐1 Ser³⁰⁷) was significantly lower (p ? 0.05) in hepatic tissue of +Cr group. After parturition, pIRS ‐1 Ser³⁰⁷ was significantly lower in muscle tissue at days 7 and 28 (p ? 0.05 and p ? 0.001, respectively), while phosphorylation of Akt at serine 473 (pA kt Ser⁴⁷³) was significantly higher (p ? 0.01) in hepatic tissue at day 7 AP in +Cr group. Chromium had opposite effect on insulin kinetics during IVGTT s obtained BP and AP . Insulin secretion was significantly reduced at day 7 BP and significantly enhanced at day 10 AP , when NEFA concentration was also significantly increased. Milk yield and ECM value were depressed in +Cr group. DMI and BCS were significantly enhanced in +Cr group at day 7 BP . In conclusion, chromium modulates insulin signalling pathway in dairy cows, but targeted signalling molecules are different in antepartal then post‐partal period, probably due to duration of exposure to chromium and different energy status between those periods.     

The Effect of Chromium Propionate on Growth Performance and Carcass Traits in Broilers

Chromium has been considered by many nutritionists as an essential nutrient for animals and humans. Research on the use of Cr from organic sources in poultry is limited. Two experiments were conducted to determine the effects of dietary addition of 0, 200, 400, or 800 ppb Cr as chromium propionate on growth performance and carcass traits in 0- to 42- or 0- to 49-d-old broilers. The results of these experiments indicate that Cr as chromium propionate improved feed efficiency in the later phases of growth and decreased mortality in one experiment but not another. Also, chromium propionate supplementation had no effect on carcass traits.     

有机铬的研究进展

铬是动物体必需的微量元素.Cr3+作为葡萄糖耐量因子(GTF)的活性成分强化胰岛素的生理功能,调节三大营养物质的代谢.与无机铬相比,有机铬易被动物体吸收,生物利用率高.大量研究结果表明有机铬在减少动物应激、改善胴体品质、提高母猪繁殖性能等方面有明显作用.     

铬在养鸡业中的运用进展

铬参与动物机体的糖类、脂类、蛋白质和核酸代谢，是动物生长发育过程中必不可少的一种微量元素。铬对鸡的生产性能、应激和免疫功能都有一定的影响。本文综述了铬对鸡营养的作用效果及机理，为铬在鸡营养中进一步运用奠定理论基础。     

浅谈测定水中六价铬分析方法的改进

针对六价铬分析实验中显色剂保存较易变色和操作不够简便的问题，提出了在显色剂配制时，用95％乙醇作为溶剂加入少量酸配制二苯碳酰二肼溶液。实验过程加酸的步骤中，使用（1＋1）硫酸和（1＋1）磷酸等体积混合酸。通过实验对比发现：改进的方法能延长的显色剂的保存时间，简化实验操作步骤，并且保证了实验分析的精密度和准确度。     

有机铬在养牛生产中的研究与应用

铬在调节动物血糖平衡和免疫反应等方面发挥着重要作用,并且具有促进动物生长、繁殖以及抗应激和改善畜产品品质等功能。本文从铬的营养特点、生物学功能以及安全性评价等方面对有机铬在养牛生产中的合理应用进行了综述。     

三价铬对葡萄糖摄取的调节作用

铬是动物和人体的一种必需微量元素,作为胰岛素的协助因子,它能改善胰岛素的敏感性、提高其活性,促进组织摄取循环中的葡萄糖,维持血糖稳定。胰岛素刺激引起的葡萄糖转运主要由葡萄糖转运体4(glucose transporter 4,GLUT-4)介导,GLUT-4在促进葡萄糖的摄取中起了关键作用。作者综述了铬的需要量、吸收机理及其通过胰岛素刺激GLUT-4来调节机体摄取葡萄糖的作用。     

高氯酸盐与铬复合污染对水稻幼苗生长的影响

通过营养液沙培盆栽试验,研究了水稻幼苗的根长、株高和鲜重对高氯酸盐（ClO4^-）、六价铬（Cr^6＋）及其复合污染（ClO4^-＋Cr^6＋）胁迫的响应。结果表明,随着污染物处理浓度的提高,ClO4^-、Cr^6＋和ClO4^-＋Cr^6＋对水稻幼苗主要生长指标根长、株高和鲜重的抑制作用越明显,呈现出明显的浓度-效应关系;在同一浓度下,ClO4^-、Cr^6＋和ClO4^-＋Cr^6＋对水稻幼苗根长、株高和鲜重的抑制率呈明显的时间-效应关系,处理时间越长,抑制率越高;复合污染对水稻生长的抑制效应大于其中任一污染物在同浓度条件下的单一污染的影响,且随着浓度和时间的增加,抑制作用也越明显;复合污染对水稻幼苗生长的交互作用类型因处理时间和浓度组合的不同而更趋复杂。     

关于分光光度法测定水质中总铬的研究

对分光光度法监测水体中总铬的关键步骤和重要指标、相关方法进行总结和分析,并做相关监测方法的比较和验证实验。