Stimulus change contemporaneous with food presentation maintains responding in the presence of free food

The presence or absence of a change in the ambient stimulus conditions upon entry into a food source controlled the frequency with which pigeons choose one of two concurrently available grain sources. Such changes characteristically accompany the production of response-produced food and account for prior reports of responding to produce food in the presence of freely available food.     

Rats' preference for earned in comparison with free food

Rats were trained to eat free food from a dish, then trained to press a lever for similar food. The free food was then presented while subjects were pressing on several reinforcement schedules. Subjects continued to press for reinforcement when one or two presses were required for reinforcement, and ate little free food. When ten presses were required for reinforcement, rats preferred free food and pressed little or not at all. It was concluded that, when work demands are not too high, rats prefer earned food to free food.     

浅析动物免疫失败的原因

动物免疫接种是预防和控制动物传染病发生的有效途径。只有选择优质的疫苗，良好的运输和保存条件及正确的使用方法，才能产生良好的免疫预防效果，保证动物健康。当前在畜牧业生产中，因为种种因素，造成动物免疫失败，致使动物发生疾病，给养殖业带来很大的经济损失。根据多年来的实践经验总结出动物免疫失败的因素如下。     

植物反应器在动物疫苗研究中的应用

用植物生产像疫苗这样高价值的药用产品,这一概念已经提出了20年.直到现在为止这项技术仍不是十分成熟.最初人们都看好瞬时表达;证实了这种疫苗对人和动物是有效的;有些植物疫苗已经进入了人的Ⅰ期临床试验,还有一些正准备进行;监管的要求比以往更加严格.生产注射用产品可能会比生产可食用疫苗容易.该技术已被证明更廉价,更易于寻找生产材料.由于植物疫苗对于生产抵御引起大流行的病毒快速应答疫苗有无法替代的优势,在未来将会为人类的发展做出巨大的贡献.     

大蒜素在养殖业中的应用

在饲料或饵料中添加适量的大蒜素,具有健胃、杀菌、止痢,止咳等多种药用功能,同时可增加采食量、促进生长、提高饲料利用率、增强免疫力、改善肉质等功能。     

转基因动物检测方法的研究进展

转基因动物检测方法随着转基因产品的逐步产业化而受到越来越多的关注。对转基因动物的检测分别从DNA、转录、翻译和整体表型的水平进行了综述,讨论了目前检测方法中存在的问题,对未来检测技术的发展前景进行了展望。     

Acoustic Activity Recorder for Burrowing Animals

The vibrations of animals digging in a dry or moist substratum may be picked up and recorded continuously by a microphone, amplifier, and recorder setup. The apparatus permits a large region, such as an activity cage, to be monitored without disturbance of the animals or special requirements for soil conditions.     

Development of Genome-Wide Scan for Selection Signature in Farm Animals

Identifying targets of positive selection in farm animals has, until recently, been frustratingly slow, relying on the analysis of individual candidate genes. Genomics, however, has provided the necessary resources to systematically interrogate the entire genome for signatures of selection. This review described important recent results derived from the application of genome-wide scan to the study of genetic changes in farm animals. These included findings of regions of the genome that showed breed differentiation, evidence of selective sweeps within individual genomes and signatures of demographic events. Particular attention is focused on the study of the implications for domestication. To date, sixteen genome-wide scans for recent or ongoing positive selection have been performed in farm animals. A key challenge is to begin synthesizing these newly constructed maps of selection into a coherent narrative of animal breed evolutionary history and derive a deeper mechanistic understanding of how animal populations improve or evolve. The major insights from the surveyed studies are highlighted and directions for future study are suggested.     

兽用退热栓剂在家兔体内的药物动力学研究

为了解自制的双氯灭痛退热栓剂在家兔体内的药物动力学过程,将6只健康家兔每次经肛门单剂量给予双氯灭痛栓剂50mg,定时收集血样,采用紫外分光光度法测定血中药物浓度后,以3p97软件包计算基本的药物动力学参数。结果显示,消除半衰期t1/2k为(5.1±1.2)h,峰浓度Cmax为(126.3±2.4)μg/mL,达峰时间tmax为(1.8±0.5)h,血药浓度—时间曲线下面积(AUC)为(20.4±1.3)mg/(L.h);双氯灭痛退热栓剂在家兔体内的药物运转过程符合一级吸收的一室模型。以上参数表明,双氯灭痛也可研制成动物直肠给药的新剂型。     

酶在动物营养研究方面的发展方向

酶在动物营养上具有广阔的前景,但目前仍有许多基础性的研究课题有待解决。通过分析畜牧生产中酶在活性测试、与饲料的作用、体内选择性及纯化制备等方面存在的问题,提出了酶学研究的一些课题和方向。     

动物生物素营养研究概况

综述了生物素的物理特性、来源、分析方法、生理功能、缺乏症、吸收和代谢方式以及动物对生物素的营养需求等,对于研究动物生物素营养功能有一定的借鉴依据。     

动物基因修饰的发展动态

基因修饰是改变动物生物性状的重要手段之一,其相关的方法和技术已逐步应用于医学、动物遗传育种、基因功能研究等方面,但在家畜育种过程中,基因修饰不应带标记基因,这就需要动物基因修饰技术得到进一步完善。因此,从转基因动物、体细胞克隆、转基因体细胞克隆、基因打靶及标记基因删除等方面,阐述了动物基因修饰的发展现状及发展趋势,为现代动物育种学的发展提供参考。