日粮中添加柑桔皮粉对产蛋后期蛋鸡钙磷代谢的影响

将 48周龄黄金褐蛋鸡 10只随机分成两组 ,对照组喂基础日粮 ,试验组用 2 5 %的柑桔皮粉等量替代基础日粮中的玉米 ,结果表明 :试验组钙磷表观代谢率为 65 79%、46 3 9% ,钙比对照组 (62 3 0 % )提高了 3 49个百分点 (P <0 0 5 ) ,磷比对照组 (4 7 5 2 % )降低了 1 13个百分点 (P >0 0 5 )。     

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.     

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.     

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。     

长期不同施氮量下黑土团聚体稳定性及有机碳含量的变化

为测定不同氮肥施用量对黑土团聚体组成及稳定性、有机碳含量及团聚体有机碳分布的影响,阐明黑土有机碳稳定性对不同施氮水平的响应机制,本研究在吉林省梨树县不同施氮水平长期定位试验田进行取样,以施氮水平不同设置5个处理,分别为T1(0)、T2(160 kg·hm^-2)、T3(240 kg·hm^-2)、T4(280 kg·hm^-2)、T5(320 kg·hm^-2),分析长期不同施氮量下水稳性团聚体组成、团聚体结构特征、土壤总有机碳含量及团聚体有机碳分布的变化,探究酸化黑土有机碳含量影响特征。结果表明：随氮肥施用水平的升高,土壤碱解氮(AN)和全氮(TN)含量先增后减,T3处理含量最高,AN和TN分别比T1处理高24.90%、10.28%;土壤速效磷(AP)的含量呈下降趋势。随氮肥用量的提高,土壤团聚体呈现大粒径团聚体向小粒径团聚体转变的趋势,>2 mm粒径团聚体下降14.55%。土壤有机碳总量随施氮水平的提高呈先增后减的趋势,施氮量为280 kg·hm^-2有机碳含量最高;>2...     

活化铁尾砂与镁改性生物炭配施对水稻幼苗生长及盐碱土性质的影响

为探究活化的高硅型铁尾砂与镁改性生物炭配施材料对水稻幼苗生长及盐碱土壤理化性质的影响以及改善盐碱地水稻生产力的可行性,本研究应用电子扫描显微镜对生物炭材料进行形貌结构观察,应用傅里叶变换红外光谱仪对生物炭材料进行官能团表征;开展盆栽实验,探究活化铁尾砂与生物炭材料配施对水稻幼苗的形态学和生理学的影响及对盐碱土的改善效果。结果表明,相比于其他生物炭材料,活化铁尾砂-镁改性生物炭材料孔隙较大,表面更加粗糙,对于养分的吸附能力强,表面的官能团丰富。盆栽实验中活化铁尾砂-镁改性生物炭配施组中水稻幼苗株高、根长、根冠比和干质量分别较对照组提高12.61%、191.49%、42.93%和100.00%;叶片的丙二醛和活性氧含量分别降低65.76%和46.46%;过氧化氢酶、超氧化物歧化酶、叶绿素和可溶性蛋白值分别升高117.35%、44.75%、55.00%和19.31%。施用活化铁尾砂-镁改性生物炭材料后,盐碱土的电导率降低,p H、总碳、总氮、土壤有效硅、总磷和总钾含量升高。研究证明活化铁尾砂-镁改性生物炭材料性能优越,并且活化铁尾砂与镁改性生物炭配施改善了盐碱土壤理化性质和养分含量,使水稻幼...     

芽孢杆菌及其胞外多糖对空心菜和茼蒿Cd吸收及土壤团聚体的影响

本研究旨在探究产胞外多糖芽孢杆菌对蔬菜镉(Cd)积累及土壤结构的影响。采用以空心菜和茼蒿为供试材料的盆栽试验,研究了功能菌株Priestia megaterium YG35和Bacillus halodurans G20降低蔬菜吸收Cd的效果和可能作用机制。结果表明,与CK相比,菌株YG35、菌株G20及其胞外多糖处理显著增加空心菜和茼蒿可食用组织干质量(37.8%～115.1%),显著降低可食用组织Cd含量(21.9%～44.2%),并使茼蒿Cd含量(0.057～0.061 mg·kg^-1)达到安全可食用标准,显著降低根际土壤有效态Cd含量(3.7%～11.7%),显著(P<0.05)增加根际土壤多糖含量(35.9%～49.5%)和蔗糖酶活性(15.3%～28.4%),促进根际土壤团聚体向大粒径转化。研究表明,YG35和G20及其胞外多糖能降低蔬菜对Cd的吸收,促进蔬菜生长,改善土壤结构,具有在Cd污染土壤上实现蔬菜安全生产的应用潜力。     

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。