Multiple ovulation and embryo manipulation in the improvement of beef cattle: relative theoretical rates of genetic change

Theoretical rates of annual genetic responses to selection in beef cattle were compared for conventional and multiple ovulation and embryo transfer (MOET) breeding schemes. Several combinations of replacement policy, mating ratio and type of selection were considered for both schemes with low, medium and high heritabilities. For MOET, four rates of embryo transfers per donor were used to represent low to moderate MOET levels. The results indicated that annual genetic responses to selection could be up to 1.3, 1.6 and 1.8 times as great for MOET compared with conventional breeding for traits of low, medium and high heritability, respectively; however, the annual inbreeding rates also were high for the MOET schemes considered. Embryo splitting, or cloning, was shown to increase accuracy of selection by 8 to 35% through the production of identical genotypes. The use of MOET in conjunction with embryo splitting in elite nucleus units could substantially increase genetic improvement for traits with low, medium and high heritabilities in beef cattle populations.     

肉牛遗传育种与繁殖技术发展趋势

肉牛业是畜牧业的重要组成部分,而良种产业化是肉牛产业发展的关键。20世纪人工授精、胚胎移植、发情控制等繁育技术的出现及常规育种技术的应用,使肉牛遗传改良取得了巨大进展,但越来越不能满足现代肉牛业发展的需求。进入21世纪,随着现代生物技术的迅速发展,肉牛育种已从传统表型和表型值育种朝着分子水平方向发展;以配子与胚胎工程、基因工程为主体的高新繁育技术将逐渐成为肉牛繁育的主要手段;体外胚胎生产、胚胎移植商业化应用将会进一步提高,实现产业化;动物克隆、转基因动物生产经不断发展与完善,将成为肉牛育种方面最具潜力的方法。论文就肉牛育种与繁育技术的发展趋势作一简要论述,旨在为肉牛生产提供理论依据与参考。     

The value of embryo transfer to cattle breeding in Britain

An analysis is made of the maximum expenditure which could be justified in embryo transfer in cattle is used to: increase the rate of genetic improvement of dairy or beef cattle; increase the frequency of twin-pregnancies; and expedite a change of breed. Estimates of maximum justifiable expenditure have been compared with an estimate of the cost of non-surgical transfer. Embryo transfer should be used in elite beef herds to increase selection intensity, particularly if bulls from such herds can be used for artificial insemination. Other commercial applications will not be economically justifiable until the cost of transfer has fallen by 50 to 80 per cent.     

肉牛遗传育种与繁殖技术应用现状

通过介绍我国肉牛遗传育种与繁殖技术方法,概述了数量遗传学、育种值估计、常规育种、分子育种技术等在肉牛育种、生产领域中的应用现状,并对人工授精技术、胚胎移植技术、胚胎分割技术、性别控制技术、体外授精技术和克隆技术等繁殖技术在肉牛科研与生产中的应用进行了介绍,以期为肉牛遗传育种与繁殖技术研究及生产提供参考.     

山西省肉牛养殖布局变动与成因分析

[目的]研究山西省肉牛养殖区域布局的演变规律,有利于科学制定肉牛养殖政策、有利于提高肉牛综合生产能力,为提升肉牛产业竞争力奠定基础。[方法]文章基于2005—2020年山西省肉牛养殖年度数据,运用区域重心分析法测算肉牛养殖区域布局重心变动的轨迹;运用面板数据模型对肉牛养殖区域布局变动因素进行了实证分析。[结果]结果表明,玉米产量、能繁母牛数量、人均收入、规模化品牌化农产品数量、支持养殖的财政政策、抑制散养的禁牧政策对山西省肉牛养殖布局有影响。[结论]提出了肉牛养殖数量应和当地的饲草资源紧密结合、发展种养一体化、降低养殖成本增加市场竞争力、积极应对环保要求、合理利用财政支持政策等建议。     

河南省肉牛遗传育种现状以及对策建议

河南省的南阳牛、郏县红牛是由河南省经过长期不断选育而形成的地方优良品种。近年来,由于牛肉需求的不断加大以及对牛肉品质要求的提高,同时由于河南肉牛的遗传改良基础好,培育具有优良肉质的新品种成为当前河南省育种产业的首要任务,与此同时,河南肉牛产业也凸显了一些新的问题。因此,本文综述了河南省肉牛遗传育种现状、遗传育种相关研究进展以及遗传育种存在的问题,从而为下一步河南省地方牛种质研究及创新利用提供对策建议。     

肉用种公牛的后裔测定

肉牛育种工作中对种公牛种用价值最终认定是通过后裔测定完成的。同期同龄比较法是在过去和将来采用并将继续使用的较为普遍的方法。随着动物育种技术的进展以及计算机技术、生物技术的不断革新和完善,ＢＬＵＰ、ＭＯＥＴ和ＩＶＦ技术和手段已应用于肉牛育种,因此肉牛的后裔测定方法也将随之改进。本文介绍肉用种公牛四种后裔测定方法。     

鲁西黄牛开放和闭锁核心群育种方案的对比分析

鲁西黄牛是中国优良的地方品种,为了更有效的制定适宜的育种方案,加快鲁西黄牛肉用品系的选育,本研究在鲁西黄牛青年公牛体系和核心群育种方案的基础上,分别设定开放和闭锁核心群育种方案,采用确定性模型评估了开放和闭锁核心群育种体系的育种效果。结果表明,开放与闭锁核心群育种方案相比,综合遗传进展提高了0.80％;育种产出量提高了9.39％;育种效益提高了10.64％;世代间隔延长了0.90％,开放核心群体系优于闭锁核心群体系。这充分说明,在鲁西牛核心群育种方案中,开放核心群育种体系优于闭锁核心群育种体系。     

Prospects for increasing the utilization of cattle embryo transfer by small-scale milk and meat producers in tropical regions

Small community cattle farmers in the tropics are facing challenges to deliver quality products whilst under pressure to increase milk and beef yields per cow. These challenges could be partially met by crossbreeding Bos taurus with Bos indicus (F1) cattle utilizing embryo transfer (ET) technology. The Bos taurus infusion would increase milk production, whilst the Bos indicus influence can improve resistance to the harsh environment of the tropics. Here, individuals from existing herds can be used to produce F1 embryos which benefit from hybrid vigour. Resultant female offspring would in turn receive an F1 embryo on reaching breeding maturity. This approach would help to provide a cost-effective, systematic approach to improve productivity in dairy and beef cattle in the tropics. However, full usage of ET, including in vitro applications, in the tropics will require improvements in procedures, resources and education.     

Prevalence and geographic distribution of bovine viral diarrhoea (BVD) infection in Finland 1993-1997

Bulk milk samples from every herd supplying milk to dairies in Finland were examined for the presence of antibodies to BVD virus (BVDV) annually during 1993-1997. The highest prevalence, 0.99% in 1994, declined to 0.37% in 1996; however, this favourable trend appeared to discontinue in 1997, where the prevalence remained at 0.41%. In 1993, sera of all individual animals from bulk milk antibody-positive herds were examined for the presence of these antibodies. Since 1994, only sera of animals from herds with a bulk milk absorbance reading greater than 0.250 in the EIA test were examined individually. Three geographic foci of BVDV antibody-positive dairy herds were resolved in 1994, one in the north-western, another in the eastern and a diffuse third in the southern part of Finland. A distinct limiting of the spread was apparent in 1997. Beef cattle were also studied during 1993-1997; in 1993 breeding units, in 1994 mainly beef suckler herds and in 1995-1997 serum samples of beef animals at slaughter were examined for the presence of antibodies to BVDV. The prevalence of seropositive herds in 1993 and 1994 was 30.2% and 3.2%, respectively, while the prevalence among slaughter animals ranged 0.8-1.6%. Seronegative animals in herds with > 50% of seropositive animals were examined for the presence of BVD-virus. A total of 40 dairy herds and two beef herds with viraemic (persistently infected, PI) animals was encountered during 1993-1997. A comprehensive control programme and a more specific, cooperatively funded eradication programme for dairy cattle were launched in 1994. These programmes most probably contributed to the decline in prevalence during 1994-1996.     

Deterministic genetic analysis of open nucleus breeding schemes for dairy cattle in developing countries

SUMMARY: A deterministic model is used to analyze the genetic properties of a two tier dairy cattle open nucleus breeding system proposed in developing countries. Theoretical selection response rates are adjusted to account for the effects of population size and structure, selection disequilibrium, sampling losses, inbreeding, and planning horizon. Optimized nucleus progeny testing, adult or juvenile multiple ovulation and embryo transfer in sib or pedigree testing schemes are used in the nucleus. All sires come from the nucleus. Females in the base herds may be recorded and selected as bull dams or donor cows in the nucleus. The predicted genetic means in the base after a given planning horizon (20 years) for a range of situations studied, is generally highest for adult sib testing, but is higher for nucleus progeny testing than for juvenile pedigree testing schemes. The genetic means are higher with more females in the nucleus and with higher reproductive and embryo transfer success rates. The genetic level of the base is higher with higher fractions of nucleus dams born in the base, but is little affected by the proportion of the total population included in the nucleus. The genetic responses are also reduced when heritability in the base is lower than in the nucleus. Policies on the formation and running of an efficient open nucleus breeding system are discussed. Key words: nucleus breeding schemes, nucleus progeny testing, multiple ovulation and embryo transfer, genetic improvement. ZUSAMMENFASSUNG: Deterministische genetische Analyse eines offenen Nukleussystems für Milchrinder in Entwicklungsl?ndern Ein deterministisches Modell wurde zur Analyse der genetischen Eigenheiten eines "Zwei-Stufen offenen Nukleuszuchtsystem" für Milchrinder für Entwicklungsl?nder verwendet. Theoretische Selektionserfolgsraten unter Berücksichtigung der Wirkungen von Populationsgr??e und Struktur, Selektionsungleichgewicht, Zufallsschwankungen, Inzucht und Planungszeitraum für optimierte Nukleusnachkommenschaftsprüfung, adulte oder juvenile multiple Ovulation und Embryotransfer mit Geschwister- oder Pedigreeprüfungspl?nen werden berechnet. Alle Vatertiere kommen von Nukleus, Muttertiere in den Basisherden z. T. leistungsgeprüft werden als Bullenmütter oder Spenderkühe im Nukleus verwendet. Das für die Basis gesch?tzte genetische Leistungsniveau eines gegebenen Planungshorizonts (20 Jahre) wird für eine Reihe von Situationen untersucht und ist im allgemeinen am h?chsten für adulte Geschwisterprüfungssysteme, aber h?her für Nukleusnachkommenschaftsprüfung als für juvenile Pedigreeprüfungspl?ne. Genetische Fortschritte sind h?her, wenn mehr weibliche Tiere im Nukleus und h?here Reproduktions- und Transfererfolgsraten existieren. Das genetische Niveau der Basis ist h?her, wenn ein h?herer Anteil von Nukleusmuttertieren aus der Basis stammt, aber es wird wenig vom Nukleusanteil der gesamten Population tangiert. Der genetische Fortschritt wird reduziert, wenn Rentabilit?t in den Basisherden niedriger als im Nukleus ist. Die Strategien zur Bildung und Management eines wirksamen offenen Nukleuszuchtsystems werden diskutiert.     

河南伊川肉牛产业发展情况调查报告

调查河南省伊川县肉牛养殖现状以及相关政策落实情况,为政府和伊川肉牛产业发展研究院的肉牛发展决策提供一定参考依据。采用实地走访、查看及与合作社或企业负责人座谈等形式进行调研。经调研发现,伊川县肉牛养殖以品质优良的安格斯肉牛品种为主,加上政府政策的积极引导,如母牛和新增肉牛栏位补贴、粮改饲补贴等,使得肉牛养殖在当地成为一种优势产业。河南省伊川县肉牛养殖产业化格局已经初步形成,并就目前肉牛养殖存在的问题给出相应的解决措施和建议。     

通辽地区科尔沁肉牛新品种（品系）培育方案

为尽快解决通辽地区无自主知识产权的肉牛品种的问题,提高本地区牛群肉用生产性能,制定了科尔沁肉牛新品种(类群)培育方案。本方案是在科尔沁牛基础上采取常规育种技术与现代分子遗传育种技术相结合的技术手段对肉用性状进行选育,培育肉牛新品种。育种方案包括新品种定向、育种任务、预期指标、育种方法及技术措施。     

秦川牛品种资源的保护与利用

秦川牛是中国五大良种黄牛品种之一,具有优良的肉用品质,做好秦川牛品种资源的保护与利用,对我国未来养牛业的发展具有重要的战略意义。本文对秦川牛的选育、改良及存在问题,秦川牛未来的育种方向,技术路线和措施作了分析和阐述。     

The effects of genotype by environment interactions in dairy cattle open nucleus breeding schemes

SUMMARY: The evaluation of open nucleus breeding systems using progeny testing or adult or juvenile embryo transfer in the nucleus is extended to include genotype by environment interactions. Knowledge of the extent of such interactions can be used to design breeding schemes and to predict realistic rates of genetic gain in the commercial environment. Interactions between the nucleus and base (commercial) herds are assumed to be more important than those interactions within tiers (e. g., among base herds). The genetic selection differentials of animals born in the nucleus and evaluated for their performance under the base conditions are reduced by a factor equivalent to the genetic correlation for economic merit between the nucleus and base test environment. This leads to a lower asymptotic genetic gain per year and longer asymptotic genetic lag with regard to the genetic improvement in the base herds. The mean genetic merit in the commercial population at a given planning horizon (20 years) is also increased as the genetic correlation for economic merit between the nucleus and base environment decreases. The applies to all the breeding systems and so the genetic correlation is a critical parameter in evaluating open nucleus breeding schemes. ZUSAMMENFASSUNG: Wirkungen von Genotyp-Umweltinteraktionen in offenen Nukleuszuchtsystemen von Milchrindern Die Bewertung offener Nukleuszuchtsysteme mit Nachkommenschaftsprüfung oder adultem oder juvenilem Embryotransfer im Nukleus wird mit Berücksichtigung von Genotyp-Umweltinteraktionen erweitert. Kenntnis solcher Interaktionen sollen bei der Zuchtplanung und zur Voraussch?tzung realistischer genetischer Fortschrittsraten in praxisnahen Situationen Anwendung finden. Interaktionen zwischen Nukleus und Basis (kommerziell) Herden werden als wichtiger angenommen als Interaktionen innerhalb der Schichten (z.B. zwischen Basisherden). Genetische Selektionsdifferentiale von nukleusgeborenen Tieren, die ihre Leistung unter Bedingung der Praxis erbringen, werden proportional der genetischen Korrelation für Wirtschaftswert zwischen Nukleus und Basismilieu vermindert. Dies führt zum geringeren asymptotischen genetischen Fortschritt pro Jahr und einem l?ngeren asymptotischen, mit genetischer Verz?gerung in bezug auf genetische Verbesserung der Basisherden. Der mittlere Zuchtwert der kommerziellen Population bei gegebenem Planungshorizont (20 Jahre) wird ebenfalls proportional der genetischen Korrelation kleiner. Das bezieht sich auf alle Zuchtsysteme, so da? die genetische Korrelation ein kritischer Parameter zur Bewertung offener Nukleuszuchtsysteme ist.     

浅谈临夏州肉牛繁育体系建设的必要性

优良品种是现代畜牧业的标志,良种化程度的高低决定产业的效益,临夏州以西门达尔为主的能繁母牛养殖已成为脱贫攻坚的重要抓手,利用现有的改良成果进行提纯推广,建立遗传特性稳定的肉牛新类群将十分必要。     

秦川牛肉用性状功能基因确定及核心群分子育种遗传进展分析

[目的]为加快秦川肉牛肉用新品种的选育进程。[方法]根据秦川牛育种目标性状,采用PCR-SSCP技术分析了21个基因的多态性,找到了4个与秦川肉牛肉用性状紧密连锁的分子标记,初步确定了影响秦川肉牛肉用性状的主要功能基因,并进一步将分子育种技术和常规育种技术紧密结合,应用于秦川肉牛早期选种。[结果]通过育种核心群多育种目标性状相比,生长发育性状的遗传进展最快,其次为繁殖性状和胴体性状,[结论]明显提高了育种工作的效率和准确性。     

宁夏海原肉牛品种改良的实践与探索

近年来,海原县肉牛产业得到快速发展。为支撑未来肉牛产业发展需求,迫切需要从品种改良技术层面破解当前育种工作中遇到的问题,为今后高端肉牛产业发展指明方向。本文分析了海原县当前繁育母牛资源现状,从肉牛产业发展目标以及制约产业发展的瓶颈问题出发,探索高端肉牛产业的内在含义,提出以西门达尔牛为母本,安格斯公牛为父本的“海原黑牛”育种方向及其在实践基础上的现实可能性。同时通过现有安格斯纯种繁育扩大母牛和选育良种安格斯公牛,为大量杂交提供优秀的公牛基因资源。希望对当前海原肉牛产业发展具有一定指导意义。     

云南省肉牛改良的瓶颈及应对措施探讨

随着国家政策对肉牛产业化的大力扶持,人民消费水平的提升,云南省肉牛养殖正面临传统养殖向现代畜牧养殖业过渡转型的历史性机遇,肉牛改良也处于一个如何打破坚冰、突破瓶颈的关键时期,如何抓住机遇,破解发展难题,做大做强肉牛养殖产业,是摆在每一个决策者面前的重大课题。文章从云南省肉牛改良历史、现状及存在的问题进行阐述,同时也提出肉牛改良的瓶颈及应对措施探讨。