外源硅钝化稻田土壤重金属Cd有效性及降低稻谷Cd含量研究

【目的】利用两种外源硅肥材料开展试验,研究外源硅对土壤重金属Cd有效性以及稻谷Cd含量的影响。【方法】以硅胶（分子式mSiO2.nH2O,含量98%以上）、液体硅肥（SiO2浓度≥23%）作为外源硅肥材料,通过在重金属镉Cd超标稻田土壤施用硅胶,在水稻分蘖期、孕穗期喷施液体硅肥,研究硅钝化稻田土壤重金属Cd有效性及降低稻谷Cd含量。【结果】施用硅胶达到100kg/667m2对降低土壤有效Cd含量有极显著效果,表明稻田施用硅胶可以钝化土壤重金属Cd有效性;施用硅胶达到100kg/667m2对降低稻谷Cd含量有显著效果,施用硅胶再配合喷施液体硅肥时,对降低稻谷Cd含量有极显著效果;施用硅胶、液体硅肥对提高稻谷产量有显著作用。【结论】基施硅胶配合喷施液体硅肥,对钝化土壤重金属Cd有效性,降低稻谷Cd含量,提高稻谷产量具有显著效果。     

重庆上市公司互保圈现象的会计思考

在市场经济环境下，贷款担保作为上市公司融通资金的一种方式，是企业的一种正常的经营行为。它可以减少交易风险、促进资本市场发展。然而，目前由于种种原因，上市公司互保不仅没有起到化解市场风险的作用，反而加大了证券市场和金融市场的风险，严重扰乱了资本市场的正常运行。因此，本文拟通过思考重庆“互保圈”现象，分析“互保圈”形成的原因及危害，并由此提出相应的对策与建议。     

Grassland research priorities: Ideas for the future

Abstract

Four levels of available dry matter (DM) were maintained on a continuously grazed irrigated Midmar Italian ryegrass (Lolium multiflorum Lam.) pasture by means of a “put‐and‐take” grazing procedure. The pasture was stocked with three successive sets of weaned lambs in winter, spring and early summer respectively. The relation between average daily gains (ADG) and available DM was positively linear At equivalent levels of available DM, gains were greater in spring than in either the winter and summer periods (P ≤0,01), but there were no differences in gains between winter and summer. There was a negative linear relation between average stocking rate (the rate required to achieve a given level of herbage availability) and available DM. Stocking rates in spring and summer were not significantly different, but both were higher (P≤0,01) than those in winter. Within the range of the differential treatments applied, relations between stocking rate and ADG were negatively linear, and there was an interactive effect (P≤0,01) between stocking rate and grazing period. Changes in ADG with a unit change in stocking rate were greatest in winter, intermediate in summer and least in spring. Gains/ha were curvilinearly related to available DM. The curves indicate that the amounts of available DM required for maximum gains/ha were least in spring, intermediate in summer and greatest in winter.

From a serial cutting trial conducted concurrently with the grazing, a growth rate curve was developed for Midmar ryegrass. This curve had two maxima, with the maximum growth rate in spring being more than double that in autumn. The in vitro digestible organic matter content and crude protein content decreased from 80,6% and 24,1% in autumn to 63,1% and 10,6%, respectively, in summer. Crude fibre content increased from 10,1 % in autumn to 30,1 % in summer.     

环境温度、饲料、性别对肉鸡氨基酸表观消化率和氮、能代谢的影响

利用72只32日龄京白904肉仔鸡公母各半研究环境温度简称温度、饲料种类和鸡的性别对氨基酸表观消化率AAAA、氮能代谢的影响。试验采用3×2×2析因设计。试验鸡在8℃、24℃、30～32℃下处理14天,43日龄时,采用改进的真代谢能TME法测定3种温度下肉用公母鸡对玉米和豆粕的AAAA、代谢能及与氮代谢有关的指标。试验结果如下:饲料种类极显著地影响AAAAP<0.01。温度和性别对AAAA测值无显著影响P>0.05。内源干物质EDM排量不受温度的影响P>0.05。高温组表观代谢能AME显著高于低温组P<0.05,而常温组与高温组及低温组间差异不显著P>0.05。性别间AME无显著差异P>0.05。温度及性别对氮校正表观代谢能AMEn无显著影响P>0.05。尿酸FUA受温度影响极显著P<0.01。氮沉积率NR不受温度的影响P>0.05。氮平衡值NB受温度影响极显著P<0.01。     

不同肉鸡用植物性饲料总磷真利用率的测定

本试验利用无磷原料配制无磷饲粮,选择低磷原料配制基础饲粮,用一定比例待测植物性饲料替代基础饲粮配制待测饲粮,通过平衡试验法测定了35日龄艾维茵肉仔鸡对玉米、豆粕、麦麸3种饲料原料的总磷真利用率。结果表明:在控制饲粮含磷量低于肉仔鸡的磷需要量,研究饲料磷的最大利用率时,肉仔鸡的内源磷排出量为(44.84±3.14)mg/d。玉米、豆粕和麦麸的总磷真利用率分别为(16.42±3.36)%、(28.34±4.90)%和(46.48±4.29)%。利用总磷含量的1/3和非植酸磷含量估计肉鸡饲料有效磷并不准确。因麦麸本身含有高活性的植酸酶,肉仔鸡可部分利用其植酸磷。     

我国货币资金体外循环的原因及对策研究

在当前的宏观经济态势下，由于实际负利率的存在，部分货币资金通过不合法的途径和方式游离出银行体系独立运行。从而形成了货币资金体外循环的态势。这是一种不确定的经济因素，反映了我国经济中的一些深层次的体制性问题。本文试图对我国货币资金体外循环产生的原因进行深入分析。以找出实际可行的对策来解决货币资金体外循环的问题。从而促进经济持续健康发展。     

不同家蝇幼虫制品对黄羽肉仔鸡营养物质可利用率、肠道菌群和血清生化指标的影响

本研究旨在探讨不同家蝇幼虫制品对黄羽肉仔鸡营养物质可利用率、肠道菌群和血清生化指标的影响。选取 １日龄的黄羽肉仔鸡 ２５２只,随机分成 ７组,每组 ３个重复,每个重复 １２只鸡。对照组饲喂基础饲粮,其余 ６组饲喂分别用 ０．２％、０．５％的家蝇幼虫肽,０．２％、０．５％的家蝇幼虫酶解物,０．２％、０．５％的脱脂家蝇幼虫粉等量替代基础饲粮中鱼粉的试验饲粮。结果表明：１）添加家蝇幼虫肽有提高干物质、粗蛋白质和能量的可利用率的趋势（Ｐ＞０．０５）,且随着添加剂量的增加而提高;添加 ０．５％的家蝇幼虫肽可显著提高粗脂肪、钙、磷和粗灰分的可利用率（Ｐ＜０．０５）。２）添加家蝇幼虫肽可显著提高试验第２周和第４周肠道乳酸杆菌和双歧杆菌的数量（Ｐ＜０．０５）,显著降低大肠杆菌和沙门氏菌的数量（Ｐ＜０．０５）。３）添加家蝇幼虫肽可显著降低试验第 ２周血清谷丙转氨酶活性（Ｐ＜０．０５）和显著提高血清总蛋白含量（Ｐ＜０．０５）,且以０．５％的家蝇幼虫肽组效果最优。在饲粮中添加不同家蝇幼虫制品均能显著降低黄羽肉仔鸡血清尿素氮含量（Ｐ＜０．０５）。由此得出,家蝇幼虫肽具有改善黄羽肉仔鸡肠道菌群、提高营养物质可利用率的作用,且以 ０．５％的添加量效果较好。     

异针茅在不同生境下补偿生长特性及其影响因素的研究

植物的补偿生长受放牧扰动和生境资源的共同影响,但何种条件易于引起植物发生超补偿生长是长期以来争论的问题。在矮嵩草（Kobresia humilis）草甸3种生境（畜圈、牧道、封育）设置扣笼和无扣笼对比样方（不放牧和放牧处理）研究了异针茅（Stipa aliena）的补偿生长特性。结果显示,异针茅分株各部分中除根系在牧道生境为等量补偿外,叶片和花序在畜圈和牧道生境均为低补偿。异针茅的分株密度、高度以及生长分配在封育生境最高。分株各部分的相对生长率在畜圈生境最低,在牧道生境最高。典范对应分析表明,对异针茅补偿生长和相对生长率影响最大的因子是采食率。尽管畜圈生境具有良好的土壤养分和水分条件,但仍不能抵消该生境家畜重度采食和践踏对异针茅的负面影响。研究结果表明,影响异针茅分株种群补偿生长的主要因素是放牧强度,而土壤资源获得性的影响相对较小。     

木聚糖酶对肉鸡能量饲料养分利用率和表观代谢能值的影响

本试验通过肉鸡代谢试验考察木聚糖酶对玉米、小麦、麦麸和米糠的养分利用率和表观代谢能(AME)值的影响,确定木聚糖酶与不同能量饲料的定量关系.试验包括4个单因子试验,分别用玉米、小麦、麦麸、米糠进行代谢试验,每种饲料设5个处理,添加不同水平木聚糖酶,每个处理8个重复,每个重复1只鸡.试验结果表明:对于玉米,当木聚糖酶添加水平为1 500 IU/kg时,与对照组相比,干物质利用率提高了0.93%(P<0.05).对于小麦,木聚糖酶水平为3 000 IU/kg时,干物质、能量和蛋白质利用率提高幅度最大,分别提高了7.02%(P<0.01)、6.78%(P<0.01)和22.31%(P<0.05).对于麦麸,在木聚糖酶为6 000 IU/kg时,干物质和能量利用率提高幅度最大,分别提高10.14%和14.73%(P<0.01);在木聚糖酶为4 000 IU/kg时,蛋白质利用率提高157.31%(P<0.01).对于米糠,在酶水平为1 500 IU/kg时,米糠的蛋白质利用率提高了27.92%(P<0.05).适宜水平的木聚糖酶显著提高了小麦、麦麸的AME值.结果表明,玉米、小麦、麦麸、米糠中每克总木聚糖的适宜木聚糖酶添加量分别为35.38、27.01、30.21和18.27 IU,每克水溶性木聚糖的适宜木聚糖酶添加量分别为1 250、273.56、753.33和937.5 IU.     

Utilization of stereoisomers from alpha‐tocopherol in livestock animals

Alpha‐tocopherol derived from natural source is a single stereoisomer (i.e. RRR‐α‐tocopherol), whereas synthetic α‐tocopherol consists of a mixture of eight stereoisomers, including RRR‐, RRS‐, RSR‐, RSS‐α‐tocopherol (the 2R isomers, R configuration at positions 2′ of the phytyl tail) and SRR‐, SSR‐, SRS‐ and SSS‐α‐tocopherol (the 2S isomers, S configuration at positions 2′ of the phytyl tail). R and S are assigned by the sequence‐rule procedure, i.e. the priorities of the substituents decrease in clockwise direction or anti‐clockwise direction at each chiral centre. Not all these stereoisomers are equally bio‐available, which can be explained by the differences in the rate of degradation, transportation and retention. Humans and livestock animals can only utilize the 2R forms, while the 2S forms have very low bio‐availability or basically are not bio‐available. The utilization of 2R forms differs between different animal species. For humans and livestock animals, RRR‐α‐tocopherol has the highest bio‐availability compared with other stereoisomers, while other 2R forms have lower bio‐availability compared with RRR‐α‐tocopherol. The relative bio‐availability of RRR‐ and all‐rac‐α‐tocopherol is related to animal species, ages of animals and assessment criteria. In general, recent literature studies have demonstrated that the relative bioavailability of RRR‐ and all‐rac‐α‐tocopherol is 2:1, differing from the commonly used conversion factor of 1.36:1. The latter was based on rat‐resorption‐gestation test. Most recent studies have shown that this conversion factor of 1.36:1 is not applicable to livestock animals and based on other metabolic functions. When IU is required to express vitamin E activity, new conversion factors need to be defined for livestock animals. Quantitative determination of bio‐availability of the individual α‐tocopherol stereoisomers will give a more detailed picture of the bioavailability of natural and synthetic vitamin E forms.