过瘤胃氨基酸对泌乳早期奶牛生产性能、乳成分和血液生化指标的影响

为研究日粮添加过瘤胃氨基酸对泌乳早期奶牛生产性能、乳成分、血液生化指标和经济效益的影响,选择96 头体况良好、健康的泌乳早期荷斯坦牛,泌乳天数为（65±15）天。采用单因素随机区组试验设计,按照年龄、胎次和产奶量相近的原则,将96 头奶牛随机分为对照组和试验组,每组48 头。对照组为基础日粮,试验组在对照组日粮的基础上添加过瘤胃蛋氨酸（RPMet）和过瘤胃赖氨酸（RPLys）,添加量分别为18 g/头·天和35 g/头·天。结果表明,与对照组相比,添加RPMet和RPLys显著提高产奶量（P=0.034）,对干物质采食量和饲料转化率无显著影响（P>0.050）;添加RPMet和RPLys显著降低乳尿素氮含量（P=0.015）,对乳脂率有增加的趋势（P=0.096）,对乳蛋白率、乳体细胞数、乳糖率和总固形物含量无显著影响（P>0.050）;添加RPMet和RPLys显著提高血清总蛋白（TP）、白蛋白（ALB）和血糖（GLU）含量,显著降低尿素氮（BUN）含量（P=0.049）,对谷丙转氨酶（ALT）、谷草转氨酶（AST）、球蛋白（GLOB）、碱性磷酸酶（ALP）、甘油三酯（TG）和总胆固醇（TC）含量无显著影响（P>0.050）;添加RPMet和RPLys可提高经济效益3.60 元/头·天。综上所述,日粮添加RPMet和RPLys可提高泌乳早期奶牛的产奶量,增加经济效益。     

甘氨酸锌在动物生产中的应用研究

锌是动物体内的必需微量元素之一,在动物生长发育和健康方面起着关键作用。甘氨酸锌作为有机微量元素具有生物利用率高、减排环保等优势。综述了甘氨酸锌对动物的生长性能、繁殖性能、免疫能力及肠道健康的影响,探讨了动物对甘氨酸锌的需要量,旨在为动物生产中科学利用甘氨酸锌改善动物健康,促进动物生长提供理论依据。     

Use of regression analysis for converting quicktest‐measured lime and fertilizer recommendations into actual values based on longer equilibration times

Abstract

Soil tests should produce data useful for making accurate lime and fertilizer recommendations aimed at optimizing chemical conditions for plant growth or providing available nutrient levels sufficient for maximum yields. In order to attain these objectives, we believe, quicktest‐computed rates have to be made equivalent to actual values through a regression adjustment. Although it may not be most desirable to use this adjustment for each new population of soils, it may be worse to try to use a function derived from one group of soils on a second group not well represented by the first.     

Performance of simple irrigation scheduling calendars based on average weather data for annual ryegrass

Poor irrigation management in pastures can lead to yield and quality reduction as well as loss of income through extra pumping and leaching of nitrate fertiliser. A number of irrigation scheduling techniques of varying levels of sophistication have been developed over the years to address limited irrigation water availability and maximise productivity. Despite this, the adoption of irrigation scheduling tools by farmers remains low. The objective of this study was to assess the use of simple irrigation scheduling calendars based on average weather data to improve irrigation management in ryegrass. The calibrated Soil Water Balance (SWB) model was used to generate simple irrigation calendars and assess effectiveness for different scenarios by mechanistically simulating water dynamics and pasture growth. Scheduling irrigation using the calendars gave similar irrigation applications, water losses and yields compared to a more scientific real-time scheduling (in response to soil water depletion by the crop). While site-specific irrigation scheduling calendars can easily be generated by consultants and irrigators, even simpler monthly estimates of average daily water use can also be useful. Application of calendars by farmers is encouraged to improve water and nutrient use efficiency of irrigated pastures, if real-time irrigation scheduling is not employed.     

农机检测实验室样品管理研究

样品管理是实验室工作中的重要环节，规范化、制度化的样品管理工作可保障实验室管理体系的有效运行。阐述实验室样品管理的总体要求与原则，从样品接收、标识、确认、流转、贮存、处理等环节人手，介绍样品全过程跟踪管理方法，为做好实验室样品管理工作提供参考。     

水稻不同需水关键期适宜灌水下限指标研究

在5 m2有底测坑内研究水稻拔节孕穗期和抽穗开花期70%～90%土壤饱和含水率灌水下限对灌溉制度、渗漏量和产量等的影响。结果表明,不同灌水条件下,灌水次数、灌水模数、灌溉定额发生较大变化,灌水次数在本田期为28～37次,灌溉定额为8 190～9 450 m3/hm2,各处理渗漏量随着灌水量的降低而降低,渗漏量为灌水量的54.22%～64.25%,拔节孕穗期较抽穗开花期需水更敏感,拔节孕穗期应保持湿润状态,抽穗开花期适宜灌水下限为90%。     

基子水分敏感指数的作物水分生态适应性评价

作物与水分的关系受到越来越多的关注.对作物水分生态适应性的科学评价有利于为制定合理的节水灌溉制度、确定适宜的灌水定额、作物布局以及种植结构调整提供依据.评价作物水分生态适应性应体现水分与作物产量的关系,基于这样的考虑.引入作物水分敏感指数(λi)的概念,并将其与作物各生育时期需水量、有效降水量合理地联系起来,计算出作物水分生态适应性度(WEAJ),以此为依据评价了北京地区冬小麦、夏玉米的水分生态适应性.结果表明:冬小麦、夏玉米的水分生态适应度分别为0.374和0.594,夏玉米的水分生态适应性强于冬小麦.评价体系综合反应了作物需水耗水特征、作物生育期内降需水平衡特征及水分与作物产量的关系,方法科学合理,适用于其他地区和作物.