动物饲养试验的关键环节及考核要素

动物饲养试验是动物营养与饲料科学研究的重要方法之一,常用来评价饲料的营养价值、筛选最佳饲粮配方、研究营养代谢及营养需要等,是目前多数农业院校动物营养与饲料科学课程的实践教学内容,其中涉及多个关键环节,包括考查因素、水平、试验动物、试验日粮、试验设计、考查指标、数据收集与整理、数据统计等,正确把握这些环节是动物饲养试验取得良好效果的关键,也是该课程中需要考核的要素。对动物饲养试验的多个关键环节进行了讨论和总结,供实践教学课程参考和借鉴,以期提高教学效果和推进实践教学改革。     

常用实验动物随机分组方法

进行动物实验时，为进行准确的统计检验，动物必须按照随机分配的原则进行随机分组。其目的是使一切干扰因素造成的实验误差尽量减少，而不受实验者主观因素或其他偏性误差的影响。随机化的手段通常采用随机数字表法。     

动物饲养试验方案设计原则及试验数据分析方法

1动物饲养试验方案的拟定及设计原则[1]1.1试验方案的拟定试验方案是根据试验目的与要求而拟定的进行比较的一组试验的总称。饲料企业常用的饲养试验方案包括以下两种。1)单因素试验方案:是指整个试验中只比较一个试验因素的不同水平的试验。2)多因素试验方案:是指在同一试验中同时研究两个或两个以上试验因素的试验。1.2试验设计的基本原则1.2.1试验要有代表性生物学代表性:要求研究对象的品种、个体具有代表性;环境条件代表性:要求试验环境条件与将来推广试验成果地区的自然和生产条件基本一致。1.2.2试验要有正确性在进行试验的过程中,应…     

关于饲养试验若干问题的探讨与商榷

饲养试验是动物营养研究中应用最为普遍的动物试验方法,但试验结果影响因素较多,若试验设计和分析方法不当,往往影响试验的代表性、准确性和可信度。本文剖析了饲养试验设计及结果分析的相关问题,并提出了几点个人见解,以期为相应的研究提供参考。     

提供实验动物适宜的饲养环境

近年来，实验动物饲养发展迅速．养殖品种多，在科学技术领域中广泛应用．畜牧科学方面．疫苗的制备和鉴定、生理试验、胚胎学研究、畜禽传染病研究以及营养饲料的分析等都利用实验动物．在饲养动物时．不仅要了解和掌握一般动物知识，特别要重视动物和饲养环境．1温度温度变动缓慢，在一定范围内．机体可以本能地进行调节与之适应．但变化过大或过急．机体将产生行为和生理等不良影响，影响动物的生长发育．一般哺乳类动物，当温度过低时．常致性周期的推迟．而温度超过30C时，则雄性动物出现睾丸萎缩，产生精子的能力下降；雌性动物出现…     

最小二乘分析在畜牧试验中的应用

最小二乘分析法是本世纪40年代初，数理统计学家创立的，70年代以来，该法在国外广泛应用于家畜育种、饲养等科研中，国内应用较少。最少二乘分析的优点是；在进行方差分析时，不仅能检验各因素水平效应差异是否显著，而且当差异显著时，可估计其均数及各因素水平的效应值（后者用常规方差分析方法是无法解决的），并可求出各因素水平组合的最小二乘均数，对原始资料进行校正。此外，该方法还适用于在试验设计或试验中，因试验动物死亡缺失或初生时的性别等造成资料的次级样本含量不等，以及便于编制电算程序。     

动物免疫失败的原因及对策

<正>免疫接种是预防动物发生传染病的主要手段,但并不是所有经过疫苗接种的动物都能达到预期的免疫效果,在生产实际中常常有多种因素的影响而发生使免疫失败而导致传染病的发生。究其原因,主要是易感动物没有获得坚强的免疫力,抗体没达到应有的水平,抵御病原体的侵袭能力大大降低。这些因素有免疫程序不合理、疫苗质量问题、疫苗血清型的差异、免疫操作不规范、饲养管理不当、应激因素、动物群体中感染某些免疫抑制性疾病等。     

实验动物伦理福利执行及思考——以华兰基因工程有限公司为例

通过梳理华兰生物工程股份有限公司试验设施配置,结合其日常工作中动物饲养、试验操作、人员素质提升等各个环节工作情况,分析了各环节对动物伦理福利的影响,并对今后具体伦理福利工作的执行进行了思考。     

动物体内致畸试验中常见阳性对照剂

致畸试验是鉴定动物致畸物的标准试验法,在评价药物、化妆品、保健品及农药的生殖毒性研究中至关重要。理想的致畸试验所用的实验动物对受试物的代谢过程应与人相近,胎盘结构亦相似,产仔多、孕期短、价廉、来源容易及操作方便。大鼠、小鼠及家兔常常是致畸试验中首选的实验动物。研究中为保持试验背景的一致,常常设立阳性对照组,其中阳性对照剂的选择对于确保试验结果的真实性及可靠非常重要。为此,查阅国内外阳性对照剂在大鼠、小鼠及家兔使用的相关文献,并进行汇总,以探讨不同的阳性对照剂对大小鼠及家兔的致畸范围、致畸情况,为有关研究提供参考。     

农场动物福利的来龙去脉

正按照国际公认标准,动物被分为农场动物、实验动物、伴侣动物、工作动物、娱乐动物和野生动物六类。世界动物卫生组织(OIE)指出,农场动物是供人吃的,但在成为食品之前,它们在饲养和运输过程中,或者因卫生原因遭到宰杀时,其福利都不容忽视。在中国,农场动物又叫"经济动物"。"动物福利"已经被一些国家用作国际贸易壁垒,这些国家以保护动物或维护动物福利为由,制定一系列措施以限制甚至拒绝外国动物食品进口,     

Cyclic variation in cattle feed intake data: characterization and implications for experimental design

Feed intake data were collected every 6 h in a 140-d feeding trial involving two pens of 15 bull calves, each using one Pinpointer single-animal feeding stall per pen. Spectral analysis of these data revealed strong cyclic patterns of feed intake. These patterns were unique to each animal and consisted of two or more cycle lengths, some up to 28 d, for each animal. Feed intake behavior is an important factor in many forms of animal experimentation. Animal researchers frequently use row-column designs, where columns represent animals and rows represent periods. Latin squares and crossover designs are common examples. Standard analysis of variance procedures are appropriate for these experiments only if certain assumptions are met; one is that if cyclic variation is present, it is identical for all animals, i.e., there is no row X column interaction. If this assumption is not satisfied, standard analysis of variance procedures will result in upward bias of the mean square error and may result in serious distortion of treatment effect estimates. This occurred using the data from the feeding trial reported in this paper. Time-series analysis of covariance greatly improved the accuracy and efficiency of estimates of treatment effects. Consideration of variations in cyclic behavior should be part of the design process in experiments using feed intake data. Guidelines for the design of experiments to take advantage of time-series methodology are given.     

Interpretation and design of nonregulatory on-farm feeding trials

Nonregulatory feeding trials are used to determine the frequency and magnitude of response to a nutritional treatment, the odds of success, and factors that influence the odds and to provide an estimate of potential economic impact. These types of trials are not appropriate for elucidating mechanisms or modes of action. Correct experimental design is critical. Important factors that impact the validity of these trials are animal randomization, potential confounding with time, identification of the proper experimental unit, and adequate replication. Animals should be assigned to treatment without a systematic influence of environmental or physiological factors. The experimental design must account for and remove these influences. The experimental unit is the smallest entity to which the treatment can be applied randomly. In commercial settings, this is often a pen of animals. In a pen feeding situation, the experimental unit is the pen, although measurements may be taken on an individual animal basis. Frequency of data collection generally does not influence the treatment effect; however, it does influence the variance associated with the observations and the power to detect differences in treatments. Statistical methods that account for repeated observations over time are required when analyzing data with multiple observations on the same animal. Improper accounting for environmental changes over time is the most common error. Other errors include improper assignment of animals to treatment, failure to replicate the treatment across multiple experimental units, lack of on-farm oversight, and poor calibration of test equipment.     

Can more be learned from selection experiments of value in animal breeding programmes? Or is it time for an obituary?

Selection experiments in laboratory animals and livestock have provided a wealth of information on genetic parameters of quantitative traits and on the effectiveness of selection in the short and long term on both directly selected and correlated traits. They have stimulated developments in theory and tests of it, and extreme selected lines continue to be source material for biological study. Some of the main questions and findings are briefly reviewed. Yet much of successful animal breeding practice has been based essentially on statistical methods, assuming where necessary the infinitesimal model, and new developments such as genomic selection are similarly not based on selection experiments. Information on the genetic architecture of quantitative traits is provided by selection experiments, but new methods for deeper studies of the biology are available. I discuss the future role for selection experiments in view of changes in funding streams and technology and conclude that there is little case for starting new experiments, but retention of existing long-term lines is desirable and DNA should be collected from all lines on a continuing basis.     

How Swedish breeders can substantially increase the genetic gain for the English Setter's hunting traits

In both Sweden (Swe) and Norway (Nor), the English Setter is used for hunting. Similar field trials are arranged to give breeders information on the dogs' hunting abilities. Our main objective was to study if a joint Swe–Nor genetic evaluation can improve accuracy compared with estimation of breeding values on a national level only. Genetic parameters for six hunting traits were estimated in univariate (within country) and bivariate (across country, of equivalent traits between countries and joint pedigree) analyses utilizing 3620 Swe records from 685 dogs and 94 414 Nor records from 7175 dogs. A mixed linear animal model was used, including fixed effects of sex, type of trial, year, month and interaction between age and class of trial, and random effects of animal, permanent environment, judge and residual. Heritabilities ranged from 0.07 to 0.13 for Swe and from 0.08 to 0.18 for Nor. The accuracies were higher in the bivariate analyses, especially for dogs with Swe trial results with an average increase of 19%. If comparing selection based on a joint genetic evaluation over phenotypic results alone (which is today's method), the potential genetic gain in Swe was almost doubled. Our results suggest that a joint genetic evaluation is especially advantageous for a population with limited information, such as the English Setter population in Swe. However, it should also be beneficial for Norwegian breeders because it makes it easier for them to select Swedish dogs, potentially resulting in faster genetic gain and lowered inbreeding rate.     

Changes in heterosis under within-line selection or reciprocal recurrent selection: an experiment on early egg production in Japanese quail

In much animal production, commercial animals are crossbreds from closed lines or breeds under long-term directional selection. Therefore it is desirable to be able to predict heterosis gains over the generations as it is done for genetic progress under within-line selection. However, heterosis is the phenotypic expression of a complex phenomenon which may involve several types of genetic effects like dominance and epistasis. In animal breeding, basic quantitative genetics theory indicates that heterosis should be proportional to (squared) differences in gene frequency between populations (e.g. F alconer and M ac K ay 1996), and it has been found approximately correct, so it is commonly used for planning crosses. Under that type of heterosis, however, selection towards the same objective in two populations should bring gene frequencies closer, and therefore it should eventually decrease heterosis. On the other hand, reciprocal recurrent selection designed to increase genetic distance between lines should eventually achieve maximum heterosis (O llivier 1982). Some experiments reviewed by brun (1982) have already compared genetic progress under within-line and reciprocal recurrent selection, but they did not focus on comparing the trend of heterosis with generations between the two selection methods. Also, heterosis was monitored periodically in some selection experiments on poultry, and results were reviewed by F airfull (1990). They were somewhat contradictory, but they generally failed to relate genetic progress to loss of heterosis under within-line selection. Moreover, in commercial production, as purebreds and crossbreds are not contemporaries and are generally maintained under very different management systems, estimations of heterosis and of the evolution of crossbred advantage over the generations may be difficult to obtain. Using the Japanese quail as an experimental animal, the present work was initiated specifically to follow the changes in heterosis brought about by selection for a single heterotic trait, early egg production (M invielle et al. 1995). For that purpose, two selection methods expected to have opposite effects on heterosis, directional within-line (or individual) selection and reciprocal recurrent selection, were applied for 13 generations in four quail lines started from two different origins, and trends of heterosis in the selected character and in weight and egg traits were evaluated.     

长毛兔巴氏杆菌病诊断与防控

2013年5月从山东某大型长毛兔场患有以鼻炎和化脓性肺炎为主要临床特征的病免中分离到1株细菌,经细菌培养、染色镜检、生化试验、PCR鉴定、动物试验证实分离菌株为荚膜血清A型巴氏杆菌;药敏试验结果表明,分离菌株对替米考星、恩诺沙星、氟苯尼考、头孢噻呋钠、阿莫西林等药物敏感;通过设计3个试验组:巴氏杆菌本场疫苗免疫试验组、恩诺沙星防治试验组、巴氏杆菌本场疫苗免疫与恩诺沙星联用试验组,每组500只长毛兔,连续观察30 d,结果发现巴氏杆菌本场疫苗免疫与恩诺沙星联用试验组对该病的防控取得了较为理想的防治效果.     

《动物机能学》课程实验教学中实验动物的合理利用

实验动物在《动物机能学》实验课教学中有着重要作用。为了在实验教学中合理利用实验动物,首先需要整合和优化其各门课程的教学内容,设计综合性实验项目,减少实验动物使用量;其次通过改进实验教学手段与方法,利用计算机辅助实验手段代替活体的使用,同时将计算机辅助实验手段与传统实验方法相结合,使学生熟悉实验过程,减少不必要的实验动物耗损;推广动物福利的3R动物实验替代方法,在学生中宣传实验动物福利和伦理学的相关知识,引导学生珍惜实验机会,严格控制实验成本。     

Genetic analysis of markers of the working test for herding dogs 2. Undesired behavior traits

The objective of the present study was to analyse the occurrence of undesirable behaviour traits registered on sheep dog trials in order to evaluate the importance of genetic and environmental sources of variation and to draw conclusions for breeding purposes. The data analysed consisted of 2745 test results recorded at 48 sheep dog trials carried out in Germany from 1994 to 1998, which were attended by 337 sheep dogs. Variance components of undesirable behaviour traits were estimated applying Restricted Maximum Likelihood methods. Additive genetic effects, permanent environmental effects of the animal and the effect of the handler were treated as random factors. Additionally, the linear multivariate animal model included the fixed effects of the age of the dogs at the sheep dog trial, sex, the level of difficulty of the exercises as well as the event itself, the starting number of the dog, the number of the dogs' tests at the particular event and the number of dogs presented on sheep dog trials by their handlers. The inbreeding coefficient was regarded as a linear covariate. The analyses were performed using all sheep dog trial classes and for each of the three classes separately. Age of the dog and starting number did not explain a significant proportion of variance for traits analysed, whereas the event of the sheep dog trial and partly the number of dogs per handler were of significant importance. The estimated heritabilities for the undesirable behaviour traits ranged from h2 < or = 0.001 to h2 = 0.07 with standard errors in the range between 0.001 and 0.06. The possibilities to select against undesired behaviour traits appear to be rather limited given the heritability estimates and the low number of progeny.     

Overview of genetic evaluation in dairy cattle

It is costly and time‐consuming to carry out dairy cattle selection on a large experimental scale. For this reason, sire and cow evaluations are almost exclusively based on field data, which are highly affected by a large array of environmental factors. Therefore, it is crucial to adjust for those environmental effects in order to accurately estimate the genetic merits of sires and cows. Index selection is a simple extension of the ordinary least squares under the assumption that the fixed effects are assumed known without error. The mixed‐model equations (MME) of Henderson provide a simpler alternative to the generalized least squares procedure, which is computationally difficult to apply to large data sets. Solution to the MME yields the best linear unbiased estimator of the fixed effects and the best linear unbiased predictor (BLUP) of the random effects. In an animal breeding situation, the random effects such as sire or animal represent the animal's estimated breeding value, which provides a basis for selection decision. The BLUP procedure under sire model assumes random mating between sires and dams. The genetic evaluation procedure has progressed a long way from the dam‐daughter comparison method to animal model, from single trait to multiple trait analysis, and from lactational to test‐day model, to improve accuracy of evaluations. Multiple‐trait evaluation appears desirable because it takes into account the genetic and environmental variance‐covariance of all traits evaluated. For these reasons, multiple‐trait evaluation would reduce bias from selection and achieve a better accuracy of prediction as compared to single‐trait evaluation. The number of traits included in multiple‐trait evaluation should depend upon the breeding goal. Recent advances in molecular and reproductive technologies have created great potential for quantitative geneticists concerning genetic dissection of quantitative traits, and marker‐assisted genetic evaluation and selection.