丝兰提取物的作用机理及其在家禽上的应用研究进展

对丝兰提取物的主要活性成分、作用机理及其在家禽上应用的研究进展进行了综述,旨在为其作为家禽饲料添加剂的应用与推广奠定理论基础。     

Brachyspira and its role in avian intestinal spirochaetosis

The fastidious, anaerobic spirochaete Brachyspira is capable of causing enteric disease in avian, porcine and human hosts, amongst others, with a potential for zoonotic transmission. Avian intestinal spirochaetosis (AIS), the resulting disease from colonisation of the caeca and colon of poultry by Brachyspira leads to production losses, with an estimated annual cost of circa £18 million to the commercial layer industry in the United Kingdom. Of seven known and several proposed species of Brachyspira, three are currently considered pathogenic to poultry; B. alvinipulli, B. intermedia and B. pilosicoli. Currently, AIS is primarily prevented by strict biosecurity controls and is treated using antimicrobials, including tiamulin. Other treatment strategies have been explored, including vaccination and probiotics, but such developments have been hindered by a limited understanding of the pathobiology of Brachyspira. A lack of knowledge of the metabolic capabilities and little genomic information for Brachyspira has resulted in a limited understanding of the pathobiology. In addition to an emergence of antibiotic resistance amongst Brachyspira, bans on the prophylactic use of antimicrobials in livestock are driving an urgent requirement for alternative treatment strategies for Brachyspira-related diseases, such as AIS. Advances in the molecular biology and genomics of Brachyspira heralds the potential for the development of tools for genetic manipulation to gain an improved understanding of the pathogenesis of Brachyspira.     

研究性教学在高校专业课程中的实践与效果

以《养禽学》课程为例,对黑龙江八一农垦大学专业课程的研究性教学改革措施和效果进行总结,以期为其他专业课程的教学改革提供参考。     

禽流感背景下家禽市场价格波动特征的实证分析

本研究利用广义自回归条件异方差模型,分析了我国家禽市场价格波动的特点。结果表明,波动性对冲击具有非对称性效果,即负冲击所引起的波动要大于同等程度的正的冲击。同时禽流感引发的价格波动具有持续性,并且禽流感疫情出现后的家禽市场价格的波动明显要大于疫情出现前。     

酸化剂在家禽生产中的应用效果

酸化剂作为环保型饲料添加剂的应用研究越来越受人们的重视。本文系统介绍了酸化剂的种类、作用机理、在家禽生产中的应用效果以及使用过程存在的问题,旨在为今后酸化剂在家禽生产中的应用提供参考。     

微卫星座位数目对家禽遗传距离估测精确度的影响

以实际测定的29个微卫星座位的基因频率为基础,分析了4个中国地方家禽品种在5、10、15、20、25个微卫星座位情况下的遗传距离估测精确度,结果表明:随着微卫星数目的增多,遗传距离估测精确度精度也随着升高。对5个水平上的遗传距离标准差进行t检验,结果表明:25个座位水平对5、10、15、20个座位水平存在显著或极显著差异,初步得出在分析群体间遗传关系时应选用较多的座位。     

家禽血样固定及其DNA的提取

研究了乙醇保存家禽血样的效果,并探索了从该血样中提取DNA的方法。结果表明,利用75％的乙醇按4:1的体积比处理家禽血样,不仅操作简便快捷,而且该血样在常温下可保存较长的时间;另外,利用酚一氯仿方法可从该血样中提取高质量的DNA,这些DNA可用于进一步的分子生物学研究。     

Influence of organic by-products and nitrogen source on chemical and microbiological status of an agricultural soil

We assessed the influence of the addition of four municipal or agricultural by-products (cotton gin waste, ground newsprint, woodchips, or yard trimmings), combined with two sources of nitrogen (N), [ammonium nitrate (NH₄NO₃) or poultry litter] as carbon (C) sources on active bacterial, active fungal and total microbial biomass, cellulose decomposition, potential net mineralization of soil C and N and soil nutrient status in agricultural soils. Cotton gin waste as a C source promoted the highest potential net N mineralization and N turnover. Municipal or agricultural by-products as C sources had no affect on active bacterial, active fungal or total microbial biomass, C turnover, or the ratio of net C:N mineralized. Organic by-products and N additions to soil did not consistently affect C turnover rates, active bacterial, active fungal or total microbial biomass. After 3, 6 or 9 weeks of laboratory incubation, soil amended with organic by-products plus poultry litter resulted in higher cellulose degradation rates than soil amended with organic by-products plus NH₄NO₃. Cellulose degradation was highest when soil was amended with newsprint plus poultry litter. When soil was amended with organic by-products plus NH₄NO₃, cellulose degradation did not differ from soil amended with only poultry litter or unamended soil. Soil amended with organic by-products had higher concentrations of soil C than soil amended with only poultry litter or unamended soil. Soil amended with organic by-products plus N as poultry litter generally, but not always, had higher extractable P, K, Ca, and Mg concentrations than soil amended with poultry litter or unamende soil. Agricultural soil amended with organic by-products and N had higher extractable N, P, K, Ca and Mg than unamended soil. Since cotton gin waste plus poultry litter resulted in higher cellulose degradation and net N mineralization, its use may result in faster increase in soil nutrient status than the other organic by-products and N sources that were tested. Received: 15 May 1996     

Use of organic amendment as a strategy for saline soil remediation: Influence on the physical, chemical and biological properties of soil

The effectiveness of adding two organic wastes (cotton gin crushed compost, CGCC, and poultry manure, PM) to a saline soil (Salorthidic Fluvaquent) in dryland conditions near Seville (Guadalquivir Valley, Andalusia, Spain) was studied during a period of 5 years. Organic wastes were applied at rates of 5 and 10 t organic matter ha⁻¹. One year after the assay began, spontaneous vegetation had appeared in the treated plots, particularly in that receiving a high PM dose. After 5 years the plant cover in this treated plot was around 80% (compared with the 8% of the control soil). The effect on the soils physical and chemical properties, soil microbial biomass, and six soil enzymatic activities (dehydrogenase, urease, protease, β-glucosidase, arylsulfatase, and phosphatase activities) were ascertained. Both added organic wastes had a positive effect on the physical, chemical and biological properties of the soil, although at the end of the experimental period, the soil physical properties, such as bulk density, increased more significantly in the CGCC-amended soils (23%) and the exchangeable sodium percentage (ESP) decreased more significantly in the CGCC-amended soils (50%) compared to the unamended soil. Water soluble carbohydrates and soil biochemical properties were higher in the PM-amended soils compared to the CGCC-amended soils (by 70% for water soluble carbohydrates, and by 34, 18, 37, 39, 40 and 30% for urease, protease, β-glucosidase, phosphatase, arylsulfatase and dehydrogenase activities, respectively). After 5 years, the percentage of plant cover was >50% in all treated plots and 8% in the control soil.     

鸡与鹌鹑属间杂交种生物学特性的观察

通过人工授精技术获得了鸡与鹌鹑属间杂种，并时它们的各种体态特征、发育规律、习性等进行了综合观祭分析。结果表明：杂交种在羽色上大多为白羽和红褐羽或黑褐色羽和黑白色羽，有别于其父母本；在生长速度上远高于鹌鹑，具有明显的超亲优势；在生活习性上，既有父本的一些习性，也有母本的一些习性，还有不同于其父母本的特性；另外通过解剖观察，所有杂交种都为雄性，且生殖器官没有发育。