欧拉羊与乔科羊杂交后代屠宰性能分析

用欧拉羊杂交改良乔科羊,生产的欧乔杂交F1代羔羊,18月龄时公、母羊体重增加9.06kg和3.77 kg,比对照组分别提高了20.92%和9.08%。试验组F1代18月龄公、母羊体重、体高、胸围及公羊体长极显著的高于对照组(P(0.01);母羊体长显著高于同期对照组母羊(P(0.05)。屠宰试验结果表明,欧乔杂交F1代18月龄公、母羊屠宰前活重比同龄的乔科羊对照组后代分别高8.94 kg和6.00 kg,胴体重比同龄的乔科羊对照组后代分别高4.88 kg和3.27 kg,差异极显著;屠宰率比同龄的乔科羊对照组后代分别高1.43%和1.10%,差异不显著。     

去除优势种后高寒针茅化草甸群落对增温增雨及其协同作用的响应

2015年6~8月在青海省海北州高寒针茅化草甸草原进行了模拟气候变化及去除优势种紫花针茅(Stipapurpurea)野外控制试验。通过设置增温2℃,增加降雨量20%,研究植物优势种丧失后气候因素对物种多样性和群落稳定性的影响。结果表明:去除紫花针茅后,增温,增雨及两者的交互作用对植物高度、盖度及地上生物量均没有显著影响;增温处理下Shannon-Wiener多样性指数、Simpson优势度指数、Pielou均匀度指数均与对照差异显著(P0.05),说明增温可以提高植物群落的丰富度和均匀度,增雨处理下3个多样性指数均为最高值;去除优势植物紫花针茅后,植物物种数与植物盖度,植物盖度及优势度指数均呈显著正相关。     

农牧民家庭档案管理系统的设计与实现

本文具体介绍了一个农牧民家庭档案管理软件系统,该系统采用数据分散收集、查询与统一集成处理相结合的两级数据库设计结构,既能适应目前基层乡镇独立建立农牧户家庭档案的发展现状,也为进一步向网络化管理平滑过渡建立了统一规范的数据基础.系统实现中针对家庭档案的特点解决了录入数据格式、录入项目灵活设置等问题,满足了家庭档案格式、主题随时间不断扩展、变化的需求.还实现了统计结果查询、多维度统计分析等数据分析的特色功能来为管理决策分析服务.这些功能为建立统一规范、可扩展的实用农牧民家庭档案提供了保障.使该系统成为具体落实农牧户家庭档案工作的一种有效实践手段.     

Effect of Water-table Level on Nitrogen Mineralization in Peat

The effect of drainage on the mineralization of nitrogen inpeat has been investigated using samples from a field experimentin which the water table has been artificially maintained atdifferent levels in five plots for a period of 7 years. Samplescut from the o–10 cm horizon were incubated in the laboratoryat 30 °C for 120 days in a moist condition (aerobic) andalso in a completely waterlogged state (anaerobic). The resultsof anaerobic incubation indicate that lowering the water-tablelevel to 18 cm significantly decreases the amount of nitrogenmineralized but that further lowering of the water level reversesthe position, mineral nitrogen increasing significantly at leastto a water-table depth of 34 cm; the position regarding samplesincubated under aerobic conditions is more complex but can beexplained on the basis of samples containing a mixture of aeratedand non-aerated material.     

Some Effects of Afforestation with Lodgepole Pine on Rates of Nitrogen Mineralization in Peat

Rates of mineral nitrogen production and carbon dioxide evolutionin incubated samples from the upper 300mm of peat beneath lodgepolepine (Pinus contorta Dougl.) have been compared with those foradjacent unplanted areas at each of six sites in the North ofScotland. Under both aerobic (moist) and anaerobic (water logged)conditions, rates of mineral nitrogen production at 30°Care strongly influenced by peatland type, sampling depth andafforestation. During the early stages of the incubation underaerobic conditions, samples of planted peat showed a more rapidaccumulation of mineral nitrogen than did samples from unplantedareas, the amounts after 17 days being 170ppm and 46ppm mineralN, respectively; after 62 days however, the difference was nolonger significant. The mean rate of CO₂ production averaged446µg CO₂ g^–1 day^–1 in planted as against728µg in unplanted peat. Under anaerobic conditions, amountsof mineral nitrogen accumulated were similar in planted andunplanted sites but a difference in accumulation between the0–150 and 150–300mm horizons in unplanted peat wassignificantly reduced beneath the trees.     

Relationship between milk production and somatic cell count in dairy cows in East Gippsland

SUMMARY The analysis of records for 75 821 herd tests on 23 700 cows in the Macalister Irrigation District of East Gippsland, using a model that also included stage of lactation, herd and cow effects, found a strong relationship between somatic cell count and milk production. Unit increases in the natural logarithm of the somatic cell count were associated with decreases in production of up to 2.6% in the range 54 598 to 403 429 cells per mL. This is equivalent to a decrease of 1.9% for a doubling of cell count from 100 000 to 200 000 cells per mL. Subclinical mastitis was assessed to be a significant source of loss in milk production in the study area.     

THE WATER BALANCE OF AN AGRICULTURAL CATCHMENT. I. ESTIMATION OF EVAPORATION FROM SOIL WATER RECORDS

Errors of measurement of soil water content with the neutron probe can be made small enough for most water balance studies; and apart from the possible damage resulting from access tube implacement, they can be readily specified. A more important problem is estimating how much water is lost from soil by drainage. A simple, graphical method is described to distinguish between drainage and evaporation from soil, based upon identification of the maximum depth at which measurable quantities of water are extracted by roots. As a result of errors in soil water measurements and uncertainties in the distinction between drainage and evaporation, estimates of soil water deficit and hence evaporation for a single profile are likely to have a precision of about ±5 mm. Larger variability is commonly found in soil water storage changes measured in replicate profiles partly because of uneven wetting of the soil during rain and partly because of non-uniform losses by drainage and root extraction. This variability requires careful attention to replication and location of access tubes when assessing the evaporation for a particular site.