标记辅助选择(MAS)及在畜禽育种工作中的应用

近年来，标记辅助选择（MAS）的应用研究，已越来越受到畜禽育种工作者的重视。应用MAS，可以更加深入地研究数量性状遗传，使遗传学研究有了新的突破。LaMe和Thompson（1990）采用模拟研究MAS与传统指数选择相比较，结果表明：对遗传力低和家系共同效应大的性状，采用MAS的效果可比传统指数选择效果提高3～4倍。Kash等（1990）对奶牛的后备公牛采用MAS的遗传改进也表明可比传统后裔测验方法提高20％～30％。所以，MAS的应用研究前景十分广阔。     

畜禽抗病育种研究进展

随着分子生物学技术的发展,抗病育种的重要性越来越显现出来。本文简要介绍了抗病育种的必要性、抗病育种的遗传基础、抗病育种的方法,最后对抗病育种将来的发展进行了展望。     

畜禽抗病育种研究进展

随着分子生物学技术的发展，抗病育种的重要性越来越显现出来。本文简要介绍了抗病育种的必要性、抗病育种的遗传基础、抗病育种的方法，最后对抗病育种将来的发展进行了展望。     

标记辅助选择及其研究进展

本文对标记辅助选择的原理,常用的数学模型,标记辅助导入的方法,及其影响标记辅助选择的因素,作了比较详细的介绍,并且对其所出现的问题提出了作者的一点看法.     

分子标记辅助选择在家禽育种中的应用

分子标记辅助选择(MAS)可在增加选择强度、提高选择准确性、利用遗传变异及扩大有效群体大小方面发挥作用.鸡的快慢羽基因、矮小型基因及裸颈基因等作为标记基因在鸡的遗传育种中已逐步得到应用,但由于还存在理论、统计学及成本上的局限性,MAS还不能在家禽育种中广泛应用,随着分子遗传、数量遗传理论及计算机技术的不断发展,MAS在家禽育种中的应用前景广阔.     

分子标记及其在标记辅助选择中的应用

运用分子标记来进行标记辅助选择,已经成为当今家畜育种的一种趋势。笔者对目前常见的几种分子标记进行了简要介绍,并就分子标记在标记辅助选择中的应用,特别就分子标记在标记辅助选择中分子标记图谱的构建、分子标记的筛选、QTL定位和与分子标记的连锁分析3个方面的应用作了较详尽的综述。     

标记辅助选择在奶牛育种上的应用

本文简要介绍了标记辅助选择的意义和类型、MAS育种体系的方法和奶牛重要经济性状QTL定位和数量性状作图的情况.通过论述国内外MAS技术在奶牛遗传缺陷痛的检测和种公牛早期选择上的应用,对我国在奶牛育种上应用MAS技术进行了展望.     

标记辅助选择及其在动物育种中的应用

本文介绍了标记辅助选择的的特点、产生背景、进行标记辅助选择的前提及影响因素,指出了当前标记一性状连锁分析所存在的一些问题,并对标记辅助选择在今后畜禽育种规划中的应用前景给予展望.     

分子标记在动物抗病育种中的研究进展

综述了利用分子标记寻找抗性/易感性基因，与抗性/易感性相关候选基因和定位抗性/易感性QTL以及特定分子标记与它们的紧密连锁关系的国内外研究动态，从而进行标记辅助选择（MAS）抗病育种。     

蜂蛟的化学成分、生理作用及其在畜禽疫病防治中的应用

蜂胶(P ropolis)是蜜蜂从植物芽孢、树皮等处采集的树脂,加入蜜蜂自身上颚腺分泌物和蜂蜡,经蜜蜂加工而成的一种具有芳香气味的胶状特质.在蜂巢中,蜂胶被用于加固蜂巢,填被缝隙或用于磨光巢房,实际上,蜂胶对蜂群的健康起着巨大的作用.在国际上,蜂胶被称为"褐色黄金",目前,人们正在倡导生产无公害的农畜产品,蜂胶作为一种纯天然、无污染的物质,以其独特的抗病、防病作用,必将在畜牧兽医业应用中发挥一定的作用.     

The sustainability, feasibility and desirability of breeding livestock for disease resistance

The sequence encoding a truncated E2 glycoprotein of the Alfort/187 strain of classical swine fever virus (CSFV) was expressed in Escherichia coli using the pET expression system and the recombinant product purified by Ni-NTA agarose affinity chromatography. The antigenicity of this recombinant protein was demonstrated by immunoblot using anti- CSFV-specific antibodies. A monoclonal antibody was produced against the truncated E2 protein and used as competitor in an ELISA for the detection of antibodies to CSFV. Specific antibodies were demonstrated by competitive ELISA (C-ELISA) as early as 21 days post-infection (dpi) in experimentally infected pigs. Seroconversion was demonstrated by C-ELISA and neutralising peroxidase-linked assay (NPLA) in all infected animals by 4 weeks. No cross-reaction with antibodies to bovine viral diarrhoea virus (BVDV) was seen in the C-ELISA using sera from experimentally infected pigs. The C-ELISA is not intended as a substitute for the NPLA. However, it is expected it will be useful for monitoring and prevalence studies. It will also assist in testing a large number of samples in the event of an outbreak.     

畜禽生长激素释放因子(GRF)的研究进展

生长激素释放因子(growth hormone- releasing factor,GRF)又称生长激素释放激素(growth hormone- releasinghorm one,GHRH) ,是存在于脊椎动物体内的一种生物活性多肽,由下丘脑合成并分泌,对脊椎动物的生长、发育及代谢调控起着极其重要的作用。其主要功能是,作为脑垂体生长激素(growth hormone,GH)的正性调控因子,能特异地诱导生长激素的合成与分泌,增高动物机体内的GH水平。而生长激素释放抑制因子(som atostain,SS)则抑制GH的合成与释放。GRF与其伴随的SS低谷诱发形成GH的分泌峰,峰的高度取决于GRF的强度及垂体对GRF的敏感…     

NRAMP1基因研究进展及其在抗病育种中的应用

抗病性能是当前畜禽育种的重要目标性状。NRAMP1蛋白可抵抗分枝杆菌、沙门氏菌等多种胞内寄生病原菌的侵染而发挥重要免疫功能，对畜禽机体抗病力影响较大。作者综述了NRAMP1基因的结构、功能、作用机制及其与抗病力的关系，并探讨了NRAMP1基因作为畜禽抗病候选基因及其应用于抗病力分子标记辅助选择的可行性。     

Genotyping strategies of selection candidates in livestock breeding programmes

Benefits of genomic selection (GS) in livestock breeding operations are well known particularly where traits are sex‐limited, hard to measure, have a low heritability and/or measured later in life. Sheep and beef breeders have a higher cost:benefit ratio for GS compared to dairy. Therefore, strategies for genotyping selection candidates should be explored to maximize the economic benefit of GS. The aim of the paper was to investigate, via simulation, the additional genetic gain achieved by selecting proportions of male selection candidates to be genotyped via truncation selection. A two‐trait selection index was used that contained an easy and early‐in‐life measurement (such as post‐weaning weight) as well as a hard‐to‐measure trait (such as intra‐muscular fat). We also evaluated the optimal proportion of female selection candidates to be genotyped in breeding programmes using natural mating and/or artificial insemination (NatAI), multiple ovulation and embryo transfer (MOET) or juvenile in vitro fertilization and embryo transfer (JIVET). The final aim of the project was to investigate the total dollars spent to increase the genetic merit by one genetic standard deviation (SD) using GS and/or reproductive technologies. For NatAI and MOET breeding programmes, females were selected to have progeny by 2 years of age, while 1‐month‐old females were required for JIVET. Genomic testing the top 20% of male selection candidates achieved 80% of the maximum benefit from GS when selection of male candidates prior to genomic testing had an accuracy of 0.36, while 54% needed to be tested to get the same benefit when the prior selection accuracy was 0.11. To achieve 80% of the maximum benefit in female, selection required 66%, 47% and 56% of female selection candidates to be genotyped in NatAI, MOET and JIVET breeding programmes, respectively. While JIVET and MOET breeding programmes achieved the highest annual genetic gain, genotyping male selection candidates provides the most economical way to increase rates of genetic gain facilitated by genomic testing.     

沙棘有效成分提取方法及其在畜禽养殖中的应用

沙棘含有多酚类化合物、有机酸类、萜类、甾体化合物、多糖等多种生物活性物质,对促进畜禽生长,提高畜禽抗氧化功能、免疫力,改善畜禽产品品质有重要作用,是一种理想的抗生素替代品。而将沙棘通过多种提取方式进行有效成分的提取,可以提高其生物利用率,有利于储存和控制用量。文章对沙棘有效成分提取方法及在畜禽养殖中的应用进行论述。     

Marker-assisted selection for commercial crossbred performance

Several studies have shown that selection of purebreds for increased performance of their crossbred descendants under field conditions is hampered by low genetic correlations between purebred and commercial crossbred (CC) performance. Although this can be addressed by including phenotypic data from CC relatives for selection of purebreds through combined crossbred and purebred selection (CCPS), this also increases rates of inbreeding and requires comprehensive systems for collection of phenotypic data and pedigrees at the CC level. This study shows that both these limitations can be overcome with marker-assisted selection (MAS) by using estimates of the effects of markers on CC performance. To evaluate the potential benefits of CC-MAS, a model to incorporate marker information in selection strategies was developed based on selection index theory, which allows prediction of responses and rates of inbreeding by using standard deterministic selection theory. Assuming a genetic correlation between purebred and CC performance of 0.7 for a breeding program representing a terminal sire line in pigs, CC-MAS was shown to substantially increase rates of response and reduce rates of inbreeding compared with purebred selection and CCPS, with 60 CC half sibs available for each purebred selection candidate. When the accuracy of marker-based EBV was 0.6, CC-MAS resulted in 34 and 10% greater responses in CC performance than purebred selection and CCPS. Corresponding rates of inbreeding were 1.4% per generation for CC-MAS, compared with 2.1% for purebred selection and 3.0% for CCPS. For marker-based EBV with an accuracy of 0.9, CC-MAS resulted in 75 and 43% greater responses than purebred selection and CCPS, and further reduced rates of inbreeding to 1.0% per generation. Selection on marker-based EBV derived from purebred phenotypes resulted in substantially less response in CC performance than in CC-MAS. In conclusion, effective use of MAS requires estimates of the effect on CC performance, and MAS based on such estimates enables more effective selection for CC performance without the need for extensive pedigree recording and while reducing rates of inbreeding.     

柱花草炭疽病及其抗病育种研究进展

柱花草是一类优良的热带豆科牧草,适于我国热带亚热带地区种植.炭疽病是柱花草生产的主要限制性因素,引起柱花草炭疽病的病原菌存在高度的遗传和致病多样性.柱花草抗病育种需要将具有多种抗性的基因导人栽培品种中,才能获得广谱的持久的抗病品种.     

柱花草炭疽病及其抗病育种研究进展

柱花草是一类优良的热带豆科牧草 ,适于我国热带亚热带地区种植。炭疽病是柱花草生产的主要限制性因素 ,引起柱花草炭疽病的病原菌存在高度的遗传和致病多样性。柱花草抗病育种需要将具有多种抗性的基因导入栽培品种中 ,才能获得广谱的持久的抗病品种。     

RNA干扰技术在动物抗病育种中的应用前景

动物疾病尤其是病毒性疾病一直是畜牧业亟待解决的问题,随着转基因技术的出现,生产遗传修饰动物来抵抗特定传染病的策略备受关注。从长远利益来看,这种基因工程动物从遗传本质上提高了畜禽的抗病能力。转基因抗病育种在未来可能成为减少动物传染性疾病的最有前途的方法之一。RNA干扰是双链RNA特异性诱导同源基因表达沉默的现象。研究证实,RNA干扰在细胞水平,小鼠模型以及动物个体的抗病毒效果是非常明显的,RNA干扰技术作为抗病毒策略为生产抗病转基因动物提供了光明的应用前景。RNA干扰技术介导的抗病转基因动物的研究相继取得了阶段性进展,抗疯牛病转基因羊和牛以及抗内源性逆转录病毒猪已经成功获得,虽然目前获得的转基因动物类型有限,但为继续生产抗病转基因家畜提供了有效的参考和依据。