Effects of different dl‐selenomethionine and sodium selenite levels on growth performance,immune functions and serum thyroid hormones concentrations in broilers

This trial was conducted in a 2 × 3 + 1 factorial arrangement based on a completely randomized design to evaluate the effects of different dl ‐selenomethionine (dl ‐Se‐Met) and sodium selenite (SS) levels on growth performance, immune functions and serum thyroid hormones concentrations in broilers. A total of 840 Ross 308 broilers (7 days old) were allocated by body weight to seven treatments (three replicates of 40 birds each treatment) including (1) basal diet (containing 0.04 mg of selenium (Se)/kg; control) without supplementary Se; (2, 3 and 4) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as SS; (5, 6 and 7) basal diet + 0.05, 0.15 or 0.25 mg/kg Se as dl ‐Se‐Met. The experiment lasted 42 days. The results revealed that dietary Se supplementation improved (p < 0.05) average daily gain, feed efficiency, immune organ index, serum immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM) and triiodothyronine (T₃) concentrations and decreased (p < 0.01) thyroxine (T₄)/T₃ ratio in serum compared with the control. Broilers receiving the dl ‐Se‐Met‐supplemented diets had higher (p < 0.05) feed efficiency, thymus index, the amounts of IgA, IgG, IgM and T₃ as well as lower (p < 0.05) serum T₄ concentrations and T₄/T₃ ratio than those consuming the SS‐supplemented diets. Serum IgA and IgM levels of broilers fed 0.15 mg Se/kg were significantly higher (p < 0.05) than those of broilers fed 0.05 or 0.25 mg Se/kg. In summary, we concluded that dl ‐Se‐Met is more effective than SS in increasing immunity and promoting conversion of T₄ to T₃, thus providing an effective way to improve the growth performance of broilers. Besides, based on a consideration of all experiment indices, 0.15 mg Se/kg was suggested to be the optimal level of Se supplementation under the conditions of this study.     

新麦草遗传多样性等位酶分析

采用不连续系统的聚丙烯酰胺垂直板凝胶电泳(VPAGE)对新疆新麦草的5个天然居群和1个栽培种遗传多样性和居群结构进行了分析.测定的6个酶系统中,确定了9个等位酶位点,多态位点百分率平均值为90.48%,平均等位基因数为2.920 7,平均预期杂合值为0.542 7.总的基因多样性中,86%存在于居群内,14%来自居群间.聚类分析以遗传距离D=0.14为分界线将6份材料明显地分为2组.研究表明,新麦草具有丰富的遗传多样性,其多样性可能与生境、人工驯化、风媒异交等因素有关.     

Physical simulation of fluid field and structure optimization in two-strand tundish

The influence of the structure and location of dam and weir on fluid flow state in a two-strand tundish is studied, and a set of optimal structure, combining with the average residence time calculated from RTD curve, is obtained. The result indicates that the fluid flow state can be changed and the path of the fluid flow can be prolonged as well as the average residence time is improved after using dam and weir. But there are some dead zones after fluid passed through the dam and weir. Combination scheme of No. one dam and weir is better than the others. Its average residence time is 299 s and the volume fraction of dead zone is 31.0%. After the optimization of flowing control parameters in tundish, the best case is that the distance between dam and weir is 290 mm and the distance between weir and the long nozzle is 383 mm. The longest average residence time is 351 s and the minimum volume fraction of dead zone is 19.0% under the above situation. Compared with that of no dam and weir, the average residence time increases by 65 s and the dead zone volume fraction decreases by 15.0%. Based on Newton formula, the calculated results show that the inclusions with diameter larger than 17.5 μm can float up within 351 s under this optimization situation.     

The Software System for Computation and Drawing of Ship Properties

The softwa re system suggested in this paper is applied to replace the traditionalhanded-computation forms. It uses the cubic sample interpolation and numerical integral,and is writ-ten with FORTRAN according to the accurate formula. With this software system,the nine sorts ofcomputation results of ship properties can be obtained. The system is con nected through SCR filewith AutoCAD,and ean draw automatically eleven sorts of pictures according to the computation re-sults.     

Friction and Wear Characteristics of Plastic Alloy Bearings under Different Lubricating Condition

Ultra High Molecular Weight Polyethylene (UHMW-PE) is a kind of high anti-wear engineering plastic with many excellent physical and mechanical performances. It has been widely applied in the field of mechanism such as bearing and pump. Effect of load, speed, time on friction and wear properties of Ultra High Molecular Weight Polyethylene(UHMW-PE)plastic alloy bearings under different Lubricating Condition are studied by using MPV-200 model friction and wear testing machine. The test results show that water lubrication reduces the friction coefficient of bearings but increases the wear rate as compared with dry friction. At the same time, wear mechanisms are analyzed systemically. It provides a theoretic basic for practical application of plastic alloy bearings     

对三农问题和农村城市化问题的若干思考

中国是一个农业大国，农业经济状况在很大程度上决定了整体经济的发展态势。对中国当前农业发展现状中的主要问题进行分析，认为只有积极进行城市化建设才能解决中国农业发展的根本问题，同时，就中国城市化的路径选择与城市化发展的中短期目标提出自己的看法。     

江苏省水稻节水灌溉技术推广模式

针对江苏省稻作区水资源、土壤、气候的特点 ,选择浅湿灌溉、浅湿调控灌溉、控制灌溉、水稻旱作灌溉等 4种技术因地制宜进行推广。在灌溉过程中 ,建立和完善了一整套的组织措施和技术措施 ,形成了江苏省水稻节水灌溉技术推广模式 ,取得了显著的效果 ,丰富了水稻节水灌溉技术推广的内容     

超高压技术在粮食产品加工中的应用

超高压技术是一种非热加工技术,因具有杀菌、保持食品原有营养成分、护色等特点,在食品行业的应用已越来越广泛。目前,超高压技术在粮食产品加工方面的应用发展较快,随着对该技术研究的不断深入,其在粮食产品加工中所发挥的作用也越来越受关注。阐述了国内外超高压技术在粮食产品淀粉改性、蛋白质改性、成分提取、致敏性降低、贮藏(灭菌灭芽)等方面的研究进展,分析了各方面研究结果的意义、应用价值和前景,并对今后应重点关注的研究方向提出了建议。     

2010—2019年安徽省执业兽医资格考试现状

为了解安徽省执业兽医资格考试现状,完善执业兽医考试制度,切实提高执业兽医水平,全面分析了安徽省执业兽医资格考试报名及通过情况、参考人员年龄结构、学历分布和职业构成等。结果显示：2010—2019年,安徽省共有10 423人参加执业兽医资格考试,其中3 684人达到农业农村部公布的助理执业兽医师和执业兽医师最低分数线,通过率为35.3%。执业兽医队伍逐步年轻化,30岁以下占58.0%,大专生以上学历达到50.0%。从业人员主要集中在行政机关和诊疗机构,报考人数少、从业人员比例低等问题比较突出。由此为执业兽医资格考试发展方向提出了建设性建议,包括完善执业兽医准入制度,完善执业兽医考试制度,建立执业兽医继续教育制度。     

光伏板对吐鲁番‘无核白’葡萄叶幕微气候、叶片质量及果实品质的影响

以吐鲁番7年生‘无核白’为试验材料,研究不同密度光伏板对‘无核白’叶幕微气候、叶片质量以及果实品质的影响,旨在找到合适的光伏板密度,为葡光互补新型栽培模式的推广提供科学依据。结果表明:随着光伏板密度的增大,叶幕空气温度降低,空气相对湿度增大,光照强度显著降低。‘无核白’葡萄叶片质量、果实品质随着光伏板密度的增大呈现出先上升后下降的变化趋势,中度遮阴条件下,‘无核白’叶片的纵、横径,叶绿素含量和果实中可溶性固形物含量均表现最佳。在吐鲁番地区采用光伏板遮阴对‘无核白’葡萄叶幕微气候有显著影响,适度遮阴有利于缓解夏季高温强光对葡萄生长发育的危害,但过度遮阴会产生负面影响。在吐鲁番地区推广葡光互补栽培模式时,建议选择光伏板的间隔为1.0 m。