肉牛选择三法

单项选择法 按顺序逐一选择所要改良的性状，即当第1个性状经选择达到育种目标后，再选择第2个性状，以此类推，直到全部性状都得到改良。该法简单易行，且就某一性状而言，其选择效果很好。主要缺点是，当1次选择1个性状时，同时期剥的性状较差的牛仍会呆在群内，影响整个牛群质量。     

影响德国牧羊犬胆量选择效果的因素

正一、遗传力胆量性状的遗传力,从两个方面影响选择效果。一方面是性状遗传力的高低,直接影响选择反应的大小。遗传力高的性状,选择差能遗传的部分就大,因此假定选择差相同,遗传力高的性状,其选择反应就比遗传力低的性状大。在选择过程中,要想通过提高性状的遗传力来提高选择的效果,是可行的。由性状遗传力的公式(H=VA/VP)可以看出,遗传力受2个方差的影响。     

判别分析法在家畜选种中的应用

1 问题的提出在家畜选种工作中,经常需要同时选择几个性状,如猪的产仔数、日增重、初生重;奶牛的产奶量、乳脂率等。对于多性状的选择方法常用的有:顺序选择法、独立淘汰法、选择指数法。顺序选择法费时较长、对于负相关的性状难以起到较好的效果。独立淘汰法是给每个性状制定一个中选标准,参选家畜必须各性状都达到所规定的中选标准才能留种,这样往往把只是某个性状没有达到中选标准而其它性状都优秀的个体淘汰     

最近二十年猪的生产性状选择试验

对最近二十年猪的生产性状选择试验及其结果进行了综述，讨论了繁殖性状和肉质性状的相关选择反应及性状间的相互关系，对我们现在的选择试验或将来设计选择试验会有一定参考价值。     

比值性状的指数选择方法探讨

以构成幽会性状的两个组分性状为目标性状,以两个组分性状和与之存在较大相关的其它经济性状为信息性状,通过约束比值性状的遗传进展,给出了用于改良比值性状的遗传进展,给出了用于改良幽会性状的选择指数制订方法。该方法避开了直接选择幽会性状而在统计和选择效率方面所遇到的诸多麻烦,从而解决了性状的综合选择问题。以提高饲料效率的选择试验为例,演示了方法的使用过程,验证了方法的作用效果。     

影响母猪繁殖性状相关基因的研究进展

母猪的繁殖性状是猪的重要经济性状,利用分子标记辅助选择(MAS)技术可有效的对母猪的繁殖性状进行遗传改良,文章分析了PRLR、FSHβ、ESR等3个影响母猪繁殖性状的基因,阐述了这3个基因的多态性对母猪繁殖性状的影响,为选择母猪繁殖性状的分子标记以及遗传改良提供理论依据和参考。     

最近二十年猪的生产性状选择试验

对最近二十年猪的生产性状选择试验及其结果进行了综述，讨论了繁殖性状和肉质性状的相关选择反应及性状间的相互关系，对我们现在的选择试验将来设计选择试验会有一定参考价值。     

母系猪繁殖性状的基因组选择策略

与生长性状相比,猪的繁殖性状具有遗传力低和限性表现的特点,通过传统育种方法很难获得较高的育种值估计准确性,且无法缩短世代间隔。因此,猪的繁殖性状选育策略应与生长性状不同。基因组选择是一种基于全基因组信息的标记辅助选择。与生长性状相比,基因组选择对提高繁殖性状(如产仔数)的预测准确性更具有优势。然而,基因组选择的育种成本较高阻碍了该技术的广泛应用。本文旨在探讨母系猪繁殖性状基因组选择的参考群体构建策略,以节省基因组育种成本和加快遗传进展。     

家畜行为及其遗传学研究进展

家畜生产育种中除对日增重、饲料报酬、瘦肉率等主要生产性状进行选择外,还要求家畜性情温和、无恶癣、母性好、恐惧行为低等良好的行为性状。因此改善提高家畜重要行为性状在生产实践中亦不容忽视。家畜重要行为性状主要指与生产及选择密切相关的母性行为、恐惧行为、攻击行为等,这些性状一般具有数量遗传学的特点,故可通过选择提高以改善其性能。本文在表观及分子水平综述了国内外家畜重要行为性状及其遗传的研究进展,以期对国内家畜行为遗传研究起到推动作用。     

猪重要经济性状选择的遗传进展

随着规模化养猪进程的加快,选育出生产性能优秀的生猪的意义日趋重要。为了促进我国养猪水平的发展,就要加强对猪遗传育种工作研究的重视程度。猪的经济性状包括繁殖性状、生长性状、胴体性状以及肉质性状,这些性状在生猪的选育改良中占据重要地位;生猪的选育方法有常规育种、转基因育种以及分子育种,随着计算机科学技术和分子生物学的发展,育种的方法也得到了发展,大量的先进的育种方法如基因组选择(GS)、标记辅助选择(MAS)、转基因和基因编辑育种等方法,有力地促进了猪经济性状的遗传改良,加快了选择进展。文章就近些年国内外猪的经济性状选择的遗传进展加以综述,旨在为我国的生猪改良提供思路和策略以及猪的选育改良提供方向。     

Correlation Analysis of Ecological Traits and Economic Traits for Chinese Native Chicken Breeds

The objective of this study was to investigate the correlation of ecological traits on body size traits and economic traits (body size traits and slaughter traits) in Chinese native chicken breeds and reveal the essential connection of three group traits.In this study,simple correlation analysis and canonical correlation analysis (CCA) were applied to estimate the relationship between local 6 ecological traits and 8 body size traits,6 ecological traits and 8 slaughter traits,8 body size traits and 8 slaughter traits of Chinese native chicken breeds.The result of ecological traits and slaughter traits suggested that the first canonical correlation coefficient was 0.536 (P < 0.01),the value of pct was 55.046% for the total correlation information.It showed that the correlation between two sets of traits mainly by mean annual temperature and dressed weight closely related to the cause,the lower mean annual temperature,the heavier dressed weight.The result of ecological traits and body size traits suggested that the first canonical correlation coefficient was 0.679 (P < 0.01),the value of pct was 54.118%,for the total correlation information.It showed that the correlation between two sets of traits mainly by latitude and shank girth closely related to the cause,the higher latitude,the smaller shank girth.The second canonical correlation coefficient was 0.556 (P < 0.05),the value of pct was 28.251% for the total correlation information.It showed that the correlation between two sets of traits mainly by forst free period and chest bone length closely related to the cause,the longer forst free period,the longer chest bone length.The result of body size traits and slaughter traits suggested that the first canonical correlation coefficient was 0.901 (P < 0.01),the value of pct was 81.063% for the total correlation information.It showed that the correlation between two sets of traits mainly by chest bone length and dressed weight closely related to the cause,the longer chest bone length,the greater dressed weight.     

奶牛生长性状研究进展与展望

近年来,生长性状在奶牛育种中备受关注,随着对奶牛生长性状研究的日益深入,其与重要经济性状间的相关性逐渐凸显出来,对奶牛的育种工作也变得越来越重要。本文就奶牛生长性状定义、遗传参数、与经济性状的关联、生长性状QTL定位、GWAS分析等方面进行了综述,并明确了生长性状在奶牛未来育种中的地位。     

分子标记在猪遗传育种上的应用

本文综述了分子标记在猪遗传育种上的应用,主要包括与繁殖、生长、胴体、肉质及抗病性状相关的分子标记。     

牛生长性状、肉质性状和胴体性状间典型相关分析

通过对牛生长性状、肉质性状和胴体性状指标的研究,分析3组性状组内及组间的相关性,揭示牛不同类型性状间的相互影响。测量记录327头牛3组性状的表型值,利用简单相关分析和典型相关分析对3组性状相关性进行深入研究。17个性状间共有74对存在极显著简单相关(P0.01),多数相关系数低于0.5。典型相关分析结果表明,3组性状间第一、第二和第三典型相关系数均达到极显著水平(P0.001),其中生长性状与肉质性状间、生长性状与胴体性状间、肉质性状与胴体性状间的第一和第二典型相关系数分别为0.525和0.350、0.993和0.623、0.698和0.394。结果显示,典型相关分析比简单相关能更准确、全面反映3组性状间的相关关系,为肉牛的选育提供科学依据。     

Genetic correlations for foal and studbook traits with racing traits and implications for selection strategies in the Finnhorse and Standardbred trotter

Genetic correlations for body measurements and conformation and functional traits in foals and studbook horses with racing traits were estimated in the Finnhorse and Standardbred. Genetic response and accuracy were estimated using records of animal, half‐sibs and parents in selection scenarios for racing traits, for foal and racing traits, for studbook and racing traits, and using records of animal, half‐sibs and parents for foal traits and racing traits of parents. Racing time and earnings were the breeding objective. Low‐to‐moderate genetic correlations for body measurements and racing traits indicated that selection favours bigger horses at all ages. Being mainly favourable for the breeding objective, genetic correlations for conformation and functional traits with racing traits were highest for the foal traits of type, trot and overall grade and for the studbook traits of character and movements. Genetic correlations for foal and studbook conformation with racing traits were low in the Finnhorse and moderate to high in the Standardbred. In foals, the highest genetic correlations were for trot with racing time (?0.54) and with earnings (0.52) in the Finnhorse, and for overall grade with racing time (?0.54) and with earnings (0.54) in the Standardbred. In studbook horses, genetic correlations were high for character with racing time and earnings in the Finnhorse (?0.68, 0.61) and in the Standardbred (?0.63, 0.70), and for movements with racing time and earnings in the Finnhorse (?0.70, 0.69) and in the Standardbred (?0.90, 0.88). To increase accuracy of conformation and functional traits, foal traits would be more useful in the index with racing traits, as being less preselected than studbook traits. The foal traits (type, trot, overall grade) having moderate heritability and genetic correlations with racing traits would be useful in multi‐trait index before a racing career, where the greatest gain is because of a shorter generation interval. It would be feasible to implement for AI stallions.     

中国地方鸡生态因子和经济性状的相关性分析

试验旨在研究中国地方鸡品种生长所在地的生态因子和鸡的经济性状（体尺性状和屠宰性状）的相关性,探讨生态因子、体尺性状和屠宰性状3组性状之间的相关关系,揭示其内在联系。对中国107个地方鸡品种生长所在地的6个生态因子及其8个体尺性状、8个屠宰性状进行了简单相关分析和典型相关分析（CCA）。结果表明,生态因子和屠宰性状两组性状间的第1个典型相关系数为0.536（P < 0.01）,贡献率55.046%,说明这两组性状间的相关性主要是由年平均气温和屠体重之间密切相关引起的,年平均气温越低,鸡的屠体重越高。生态因子和体尺性状两组性状间的第1个典型相关系数为0.679（P < 0.01）,贡献率54.118%,纬度和胫围相关性最大,纬度越高,胫围越小;第2个典型相关系数为0.556（P < 0.05）,贡献率28.251%,无霜期和龙骨长相关性最大,无霜期越长,龙骨长越长。体尺性状和屠宰性状两组性状间的第1个典型相关系数为0.901（P < 0.01）,贡献率81.063%,说明这两组性状间的相关性主要是由龙骨长和屠体重之间密切相关引起的,龙骨长越长,鸡的屠体重越大。     

Selection of Objective Traits and Estimation of Economic Weights for Chinese Simmental Beef Cattle

In order to breed a beef line in Chinese Simmental cattle,this research defined breeding objective traits and selected traits according to real breeding condition of Chinese Simmental beef cattle.Using the balance method to calculate the marginal benefit of each objective trait and getting the corresponding economic weight of breeding objective traits through the standard value of the error corrected marginal benefit of breeding objective traits.The results showed that breeding objective traits mainly included growth traits (including weaning weight,fattening daily gain,18th month weight),carcass traits (including carcass quality,dressing percentage,pure meat percentage) as well as reproductive traits (including age at first calving,calving interval,stay group time).In the current market and production conditions,the marginal benefit of the breeding objective traits were 17.93 yuan/kg,16.2 yuan/kg,7.17 yuan/kg,297.99 yuan/grade,497.82 yuan/%,594.46 yuan/%,-3.62 yuan/d,-26.55 yuan/d and 232.75 yuan/y,respectively,and the ratio of relative economic weights of three kinds of traits was 31.49%:15.86%:52.65%,similar to 2:1:3,and reproductive traits occupied larger economic weight,was better than growth traits and carcass traits.The results indicated that reproductive traits played an important role in the process of breeding in Chinese Simmental beef cattle,and we needed to strengthen the selection of reproductive traits.     

鲁西斗鸡体尺、体重及屠宰性状间的典型性相关分析

对鲁西斗鸡的体尺、体重和屠宰3组14个性状进行测定,并对这些变量进行了典型性相关分析。结果表明,体尺指标(胸深、胸宽、胫长、体斜长、龙骨长)间的相关系数为0.682~0.767;体重性状(初生重、180日龄重、日增重)间的相关系数为0.306~0.935,屠宰性能(胴体重、屠宰率、半净膛重、半净膛率、全净膛重,全净膛率)各项指标间高度相关,相关系数为0.945~0.986。体重性状和体尺性状间、体重性状与屠宰性状间及体尺性状与屠宰性状间的第一个典型相关系数差异极显著,其典型相关系数分别为0.705、0.560和0.878,贡献率分别为0.979、0.984和0.820。     

Genetic correlations between competition traits and traits scored at breeding field-tests in Icelandic horses

Relationships between breeding field-test traits and competition traits were studied to investigate whether the latter could be usefully included in the genetic evaluation of Icelandic horses. The current method of genetic evaluation is based on records from breeding field-tests only. The breeding field-test data included 16 401 individual records of Icelandic horses evaluated in 11 countries during 1990–2005. Competition results included 18 982 records of 3790 horses competing in sport and gæðinga competitions in Iceland and Sweden during 1998–2004. In the breeding field-tests, eight conformation traits and eight riding ability traits were scored; height of withers was also recorded. These traits were analysed together with the competition traits tölt(comp), 4-gait, 5-gait and pace test, in bivariate analyses. Animal models were used; the fixed effects for breeding field-test traits included sex by age interaction and country by year interaction. For the competition traits the model included fixed effects of sex, age and event, and a random permanent environmental effect. Estimated heritabilities and genetic correlations for breeding field-test traits were consistent with earlier results; heritabilities ranged from 0.20 to 0.67, and moderate to high genetic correlations were estimated between many of the riding ability traits, and between riding ability traits and some conformation traits. The estimated heritabilities for competition traits were about 0.20, and genetic correlations between competition traits varied from − 0.12 to 1.00. In general, high genetic correlations were estimated between breeding field-test riding ability traits and competition traits. Moderately positive genetic correlations were found between some breeding field-test conformation traits and competition traits. Competition traits add information relating to the breeding goal of the Icelandic horse; they should therefore be added to genetic evaluation in future.     

牛血液蛋白多态性与数量性状的关系

血液蛋白多态性在选种中可视为一类附加性状。数量性状是由许多彼此独立的基因作用的结果 ,每个基因对性状的作用甚微 ,但遗传作用的机制仍服从孟德尔规律。牛的生产性能如产奶性能、生长性能和繁殖性能是通过有关生理活动来实现的 ,这涉及到酶、蛋白质等一系列生物活性物质的功能发挥 ,由于蛋白质 (酶 )多态性等生化性状与生同来 ,终生保持相对稳定 ,对外界环境保持相对独立性 ,如能找到生化性状对生产性能的预示物 ,就可提早选种 ,加快育种进度。本文综述了血液中血红蛋白、运铁蛋白、血清白蛋白位点的不同基因型多态性与产奶性能、繁殖性能、生长性能、疾病发生的研究进展情况