纤维素酶渣替代黄豆饲喂杂交奶牛试验

采用纤维素酶渣替代黄豆对西黄杂奶牛(西门塔尔×本地黄牛)作饲喂对比试验,并对其产奶量及奶品质进行观察。结果表明:试验组比对照组牛日产奶量平均提高1 88kg,其乳蛋白和乳糖含量也有不同程度的提高。     

The evolution and application of enzymes in the animal feed industry: the role of data interpretation

ABSTRACT

1. Enzymes have been used commercially for nearly 40 years and save significant costs through sparing of expensive nutrients but the mechanism by which this is achieved is still debated.

2. The research focused on non-starch polysaccharidase (NSPase) enzymes is used as an example of where greater progress could have been made if the details of the work had been described more fully and the analysis of the data generated had been broader in scope and more critical.

3. Lack of standardisation of the details presented in the materials and methods has been identified as a significant barrier to meaningful retrospective analysis and thus limits advances in the understanding of the mode of action of these enzymes.

4. The identity of the enzyme employed and its activity is often lacking, and more importantly the purity is rarely disclosed. Contaminant activities which are neither listed nor assayed could play a significant role in the responses observed.

5. The dose optimum of most enzymes is often considerably higher than that employed in most studies. Thus studies claiming synergy between two ‘activities’ should ensure that the response is not related to each enzyme simply augmenting the dose of just one activity in the finished feed. This is a common problem, and coupled with the lack of factorial experiments to justify the presence of each enzyme in a multi-enzyme product, it is not surprising that there is still debate as to whether single or multi-enzymes are best suited poultry rations.

6. The three proposed mechanisms for NSPases (viscosity, cell wall and prebiotic) are discussed, and along with their strengths and weaknesses it is suggested that a re-evaluation of each is needed. Viscosity may have to be re-evaluated as being a function not only of the cereal being fed, but of the age of the animal as well. The cell wall theory as described is poorly modelled in vitro and hence the validity of these data is questioned. The prebiotic theory may need significant modification as it appears that the quantities of oligomers produced are insufficient to generate the additional volatile fatty acids (VFA)’s reported. It is likely that all three mechanisms play a role in the responses observed, but the prebiotic mechanism probably plays by far the most important part in low viscosity diets.

7. Future research would be improved if it considered all potential mechanisms when designing a trial. Significant failings are apparent as a result of adherence to tenets in explanation of the results. Most importantly, it should be emphasised that a hypothesis is there to be tested, not defended.     

面向多类型土壤有机碳定量反演的天基高光谱探测参数研究

星载高光谱仪器的光谱通道以及光谱分辨率和信噪比等核心参数设置直接影响土壤有机碳定量反演精度。本研究开展了卫星载荷光谱分辨率、信噪比、光谱特征波段对不同土壤类型有机碳反演影响的研究,提出了基于大气传输模型、光谱分辨率分析模型、信噪比分析模型、特征波段的提取分析模型以及偏最小二乘回归反演模型的面向不同土壤类型有机碳监测的高光谱卫星“地面–大气–仪器–观测–反演”全链路仿真分析方法,实现了土壤类型、大气效应、仪器特性参数、反演方法的耦合影响分析。结果表明：①3种类型土壤有机碳反演的最佳光谱分辨率均在10~20 nm。②不同土壤类型对观测的信噪比需求不同。对于Phaeozem的有机碳监测,较另外两种土壤有更高的信噪比需求。③在不同特征波段提取分析方法下所需的最佳光谱分辨率和信噪比一致。不同类型土壤光谱数据提取出的特征波段不同,其中反演效果最佳的土壤类型为Chernozem,特征波段数为26个,R²=0.826 5,RMSE=3.438 9 g/kg。④反演模型与仪器特性参数无耦合关系,同一类型土壤不同反演算法的最佳光谱分辨率和信噪比需求一致。⑤Chernozem有机碳最佳反演参数需求为光谱分辨率15 nm,信噪比大于506.66,特征波段提取数为26个;Kastanozem有机碳最佳反演参数需求为光谱分辨率17 nm,信噪比大于331.42,特征波段提取数为22个;Phaeozem有机碳最佳反演参数需求为光谱分辨率15 nm,信噪比大于432.51,特征波段提取数为19个。     

西北太平洋公海柔鱼和日本爪乌贼个体发育期营养生态位变化分析

为了更好的了解柔鱼和日本爪乌贼个体发育期营养生态位变化,根据2021-2022年“淞航”号渔业资源调查船所采集36尾柔鱼和30尾日本爪乌贼样本,对其眼睛晶体进行了碳氮稳定同位素分析。结果表明：柔鱼个体δ13C、δ15N值变化幅度分别为0.10‰-1.68‰、0.79‰-7.51‰;日本爪乌贼个体δ13C、δ15N值变化幅度分别为0.15‰-1.20‰、0.81‰-7.05‰。柔鱼、日本爪乌贼生态位面积变化范围分别为0.40‰2-5.85‰2、0.27‰2-5.36‰2。GAM模型分析显示：柔鱼眼睛晶体δ13C、δ15N与晶体直径均具有显著的相关性（P<0.01）,偏差解释率分别为31.9%和34.3%。日本爪乌贼眼睛晶体δ13C、δ15N与晶体直径均具有显著的相关性（P<0.01）,偏差解释率分别为12.9%和19.4%。分析认为,个体营养生态位的变化幅度较大,侧面反映了西北太平洋黑潮-亲潮过渡区同位素基线值变化幅度较大;该海域的柔鱼、日本爪乌贼个体摄食水平存在很大差异;个体发育和基线值是影响组织δ13C、δ15N值的因素。     

湖南小溪国家级自然保护区生态旅游资源的SWOT分析

对湖南小溪国家级自然保护区进行了生态旅游资源的SWOT分析,其优势是:良好的原始次森林和高品位的自然资源、森林浴的理想场所、优秀独特的人文资源、丰富的植物基因库存.但是可进入性差、知名度低、接待设施及能力较差.周边存在张家界国家森林公园和栖凤湖风景区的竞争威胁.分析了发展机会.     

运筹帷幄的决策工具——运筹学

运筹学是关于做决定的科学,运筹学集数学和其他科学方法为一体,对现实问题进行模型化并提出解决方案,把它科学地应用到各企业管理中,可有效地帮助企业做出合理的决策.     

Evaluation of host and bacterial gene modulation during Lawsonia intracellularis infection in immunocompetent C57BL/6 mouse model

BackgroundProliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium.ObjectivesThis study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue.MethodsWe assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis.ResultsThe mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × l0⁷ bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses.ConclusionsThis is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.     

常用软件绘制使用林地可行性报告附图方法的比较

使用林地可行性报告的附图是林业专题图类型之一。该类图纸是项目成果重要的组成部分,对文字内容具有补充和说明等作用。本文以一个简单的实例,比较了几类常用软件绘制专题图的各自特点,并简介了综合使用的方法。     

土壤微塑料影响植物生长的因素与机制研究进展

土壤中的微塑料可通过多种方式影响植物生长,并且其在植物体内积累会最终通过食物链进入人体,厘清微塑料对植物生长的影响及机制,有助于系统掌握其在土壤-植物体系中的环境行为。微塑料的赋存状态和理化特征均可影响其对植物的作用效果,本文从粒径、形状、浓度、种类、塑料添加剂和老化程度等方面,梳理了土壤微塑料影响植物生长的主要因素及作用机制,并对未来研究的重点内容提出展望,以期为进一步明晰微塑料对土壤生态系统的影响提供参考。     

不同氮肥形态对李氏禾铬富集能力的影响

为了优化李氏禾（Leersia hexandra Swartz）铬修复时的施氮效率,通过盆栽试验,研究了5种氮肥形态（硝酸钙、尿素、氯化铵、硝酸铵、硫酸铵）对李氏禾铬修复性能、生长指标和根系指标的影响。结果表明：与对照（不施氮肥）相比,施加的5种形态氮肥均促进了李氏禾生长,提高了根系活力,改变了根系形态特征,有利于提高李氏禾铬含量、铬累积量、富集系数和土壤铬去除率。施加硫酸铵的李氏禾生物量和根平均直径最大,分别为对照的5.54倍和1.51倍,其根系活力比对照增加108%;施加硝酸铵的李氏禾总根表面积和总根体积最大,分别为对照的2.17倍和1.99倍（P<0.05）。相关性分析结果表明,李氏禾的生物量、根平均直径、总根表面积、总根体积和根系活力均与土壤铬修复效率有关。其中,施加硫酸铵处理的富集系数和土壤铬去除率最高,分别为对照的1.45倍和5.56倍。研究表明,施加硫酸铵比其他氮肥形态更有利于提高李氏禾铬污染土壤修复效率。