主成分分析在奶牛产奶量选择中的应用

应用主成分分析法分析了荷斯坦奶牛体尺及乳房性状的8个指标，选取了累计贡献率达85％以上的前5个主成分，并分析了5个主成分与产奶量的相关关系。结果表明，主成分Ⅰ有可能成为荷斯坦奶牛产奶量选择的指标。     

基于主成分和模糊C均值聚类的畜牧业发展状况分类研究

运用主成分分析法对影响我国31个省(市、自治区)畜牧业发展状况的15个影响因素进行压缩,得到3个主成分并利用模糊C均值聚类(FCM)算法将各省、市、自治区的畜牧业发展状况进行了聚类。研究表明:分类结果与实际吻合较好,证明利用主成分分析法和FCM聚类法对畜牧业发展状况进行评估分类是科学合理的。     

基于主成分分析综合评价23份白沙枇杷果实营养品质

为了科学的评价不同白沙枇杷品种果实品质指标,建立高效白沙枇杷果实品质评价体系,本研究通过相关性分析法和主成分分析法对23份白沙枇杷果实的11个品质指标进行了系统分析。结果表明,不同品种的果实各个品质指标之间存在较大差异,且具有不同程度的相关性。采用主成分分析法从11个品质指标中提取出4个主成分因子。综合相关性分析和主成分分析,可溶性糖、可滴定酸、氨基酸(AA)和单果重作为白沙枇杷果实品质性状评价的核心指标。采用相关性分析和主成分分析综合评价方法为评价品质优良的白沙枇杷品种提供参考依据。     

四川境内山羊群体毛色性状的主成分分析

用主成分分析法研究了四川境内11个山羊群体毛色位点的遗传变异类型，结果表明：山羊群体85％以上的遗传变异来源于6个变异类型；以主成分为依据的欧式距离聚类分析结果，与已有山羊群体系统的认识基本一致。     

平武黄牛体尺性状的主成分分析

用主成分分析法对武黄牛体尺性状的13个性状指标进行了处理,选择累计贡献率85．938％的7个主成分进行分析,明确了平武黄牛的体型特征,提出了平武黄牛体尺性状的选育方向和重点。     

苗期紫花苜蓿品种抗旱性初步研究

运用多元统计分析方法,以来自、美国、澳大利亚、加拿大及中国的22个紫花苜蓿Medicago sativa品种（种群）为试验材料,对紫花苜蓿在苗期进行短期干旱胁迫,依据试验测定的15个形态指标和生理指标,应用主成分分析、聚类分析法,对22个紫花苜蓿品种试验材料的抗旱能力进行综合评价。通过运用主成分分析法将15项相关的抗旱性指标简化为5个独立且功能明确的主成分,并以5个主成分的得分系数运用聚类分析法把22份材料聚为三大类,从而将22份材料分为强抗旱性品种、中抗旱性品种、弱抗旱性品种,为下一步抗旱机制的研究提供参考。     

鸡舍环境监测传感器布置方法研究

为了探讨鸡舍温度、湿度传感器的布置数量和位置选择，从而提高对鸡舍环境监测的效率，试验将90个温度、湿度传感器分三层均匀分布在鸡舍中，分析舍内温度和湿度变化规律，并运用主成分分析法将监测结果进行线性变换，根据监测点优化率与累计方差贡献率的调和评价指标确定监测点的最佳数量，计算主成分与原始数据的累计因子负荷量并以此确定最终传感器监测点位置。结果表明：八层叠层笼养鸡舍内不同监测点温度差和湿度差变异大，分别可达5～8℃和25%～35%。基于主成分分析方法剔除邻近点后，确定了6个温度监测点(25,35,52,61,79,83号)和7个湿度监测点(1,16,32,50,52,61,79号)为最优监测点，其中52,61,79号既是温度监测点又是湿度监测点，共10个监测点，在这10个监测点处安装传感器，对应的温度和湿度累计方差贡献率分别为0.94和0.89,并通过温度和湿度的变化规律验证了选择结果的合理性。说明主成分分析法获得的监测点数量和位置可有效代表蛋鸡舍温度、湿度的空间变异性，提高蛋鸡舍环境监测效率。     

浙江主栽果桑品种品质性状评价

为了更好地了解浙江地区主栽果桑品种性状,推进果桑产业多元化发展,选取浙江省主栽的8个果桑品种的桑果农艺性状调查与加工品质性状测定,并通过主成分分析法对桑果进行品质综合评价.结果表明,8个桑果品种桑果的各项性状存在较大的差异,21个农艺与品质性状当中,有20个变异系数大于10％.主成分分析共提取了5个主成分,累积方差贡献...     

科学选择粪污治理技术

本研究构建了生猪发酵床养殖的区域适宜性评价指标体系，以湖南省为例采用主成分分析法进行了综合分析。结果表明，影响生猪发酵床养殖的第一主成分为地方财政收入和人均地方财政收入，生猪发酵床养殖适宜在地方财政状况较好的地区率先推进。     

我国沿海省市经济发展综合实力的主成分分析

本文基于主成分分析法,对反映我国10个沿海省市的经济发展的11个指标进行统计分析。得到的结果是:第一主成分是经济发展水平与发展潜力;第二主成分是:经济发展活力;第三主成分是:外商投资进出口比重。此结论基本上是正确合理的,对评价我国沿海省市经济发展综合实力具有一定的指导作用,可以提高评价过程效率、节约成本。     

A Survey of Pig Production Systems in the Rain Forest of the Pacific Coast of Colombia

A questionnaire-based survey was conducted in small-scale pig farms in the rain forest of the Colombian Pacific coast in order to study aspects of reproduction, nutrition and productivity. A total of 124 farmers was interviewed. They owned, on average, 13.6 pigs, including 2.3 sows, mainly of the Zungo breed. Pigs are reared in extensive systems and are allowed to wander freely in search of food. The sows produce, on average, 9.6 piglets/litter but, owing to poor sanitary conditions, 1.5 are born dead and only 6.3 are weaned alive. Two-thirds of the sows have five litters or more and the boars are also kept for a long time. This leads to high consanguinity rates within the herd and low productivity. Diets are based on maize, banana, tubers (taro, cassava) and fruits (peach palm, among others), and are rich in energy but poor in protein and minerals. The lack of protein and mineral sources appears to be the main limiting factor of these extensive production systems. Tree forages could partially solve the problem but are used by only 2% of the farmers. It is concluded that decreasing inbreeding, better piglet management and provision of balanced diets are areas that require immediate improvement.     

Disorders of the pharynx.

Pharyngeal disorders are complex and difficult to treat. Disorders that lead to anatomic derangement, such as trauma and neoplasia, can significantly affect the function of this organ. Pharyngeal dysfunction can manifest as dysphagia, persistent palatal displacement, or exercise intolerance. Secondary complications are serious and life threatening and include aspiration pneumonia, weight loss, and death. Pharyngeal disorders that are only recognizable during strenuous exercise are difficult to diagnose and are treated with limited success, even though they are responsible for significant economic losses with performance animals.     

Diseases of quail

An increasing number and variety of quail are being kept for food production, experimental use, release on hunting preserves, preservation of endangered species, zoological display, and as companion birds. Quail are susceptible to a variety of noninfectious, infectious, and parasitic diseases. Because they are related to chickens and turkeys, many of the diseases in quail are similar to those in poultry. In this article, the diagnostic characteristics of diseases affecting quail are presented along with information on their prevention, control, and treatment.     

Diagnostic investigation of emerging viruses of companion animals.

In this article, the authors are specifically concerned with the timely and accurate detection of emerging diseases of small animals that are viral in origin. Veterinarians are bound to encounter emerging viruses in their practice. The problem is unavoidable, because viruses are highly mutagenic. Even the immune response dictates the nature of virus that evolves in a host. If the clinical signs and diagnostic methods fail to correlate, the veterinarian should work with the diagnostic laboratory to solve the diagnostic puzzle.     

Implications of mycotoxins in animal disease

Mycotoxins are formed on animal feeds when conditions of moisture and temperature permit the growth of naturally occurring toxigenic fungi. In general, mycotoxins are low molecular weight, nonantigenic substances, many of which are relatively heat stable. Mycotoxins can cause acute disease episodes when animals consume critical quantities of them. Specific toxins affect specific organs or tissues such as the liver, kidney, oral and gastric mucosa, brain, or reproductive tract. In acute mycotoxicoses, the signs of disease often are marked and directly referable to the affected target organs. Most frequently, however, concentrations of mycotoxin in feeds are below those that cause acute disease. At lower concentrations, the effects of mycotoxins are more protean. They reduce the growth rate of young animals, and some interfere with native mechanisms of resistance and impair immunologic responsiveness, making the animals more susceptible to infection. These effects on immunity and resistance are difficult to recognize because the signs of disease are associated with the infection rather than with the mycotoxin that predisposed the animal to infection. Animals vary in their susceptibility to some mycotoxins, according to the species and age of animal; young growing animals are more susceptible to certain mycotoxins than are adults. The major effects, sources, and dose response relationships of mycotoxins important to the health of food-producing animals are presented in accompanying tables.     

Neoplasms of the spine.

Although the treatment of central nervous system neoplasms generally is unrewarding, some animals with spinal neoplasia may, for a variety of reasons, be successfully managed for extended periods of time. The veterinary profession has greater experience with spinal surgery than with intracranial surgery. As a result, surgeons are more willing to attempt and more successful at removing or debulking spinal neoplasms. Additionally, there are more affordable and accessible diagnostic procedures available to evaluate the spinal cord than there are to evaluate the brain. Finally, the majority of tumors that affect the spinal cord are extramedullary and are therefore amenable to attempts to remove them surgically.     

Chemistry of immunomodulators

A large number of synthetic derivatives, inorganic compounds or naturally occurring substances are able to depress, regulate or enhance the immune response. Immunomodulators, among which some are chemically well defined and others are complex preparations, exhibit a great variety of chemical structures which are briefly reviewed, without details on their immunopharmacological properties. These molecules allow access to a new type of therapy which aims at acting on the host defense mechanisms.     

Supervision of rabbit husbandry--report of a public health veterinarian

Rabbits are wide spread farm animals and pets, which are kept in the most diverse areas. The evaluation of rabbit husbandries in regard to animal welfare legislation is often complicated by different and contradictory recommendations of various organisations, which should partly be revised. In the following article some regulations and guidelines are discussed. In addition, some aspects for the keeping of rabbits in accordance with their behavioural needs are outlined, some frequent shortcomings regarding the keeping of rabbits are described and possibilities for taking official measures are presented.     

Comparison of accreditation practices and standards of US schools of medicine and veterinary medicine

There are 126 medical education programs leading to the MD degree in the United States, and 16 in Canada, that are accredited by the Liaison Committee on Medical Education (LCME). This article summarizes the current policies and procedures used by the LCME and traces their historical development. The external factors that have acted to influence accreditation in the United States, such as recognition of accreditation agencies by the US Department of Education, are then described. Finally, comparisons are drawn between the accreditation systems for medical education and veterinary medical education programs.