共查询到20条相似文献，搜索用时 31 毫秒
1.
Despite challenges in the implementation of livestock genetic improvement programs in developing regions, including centralized nucleus breeding schemes, these programs can contribute to the improvement of the livelihood of smallholder farmers. In this paper, we present a community- or village-based breeding scheme in which breeding activities are carried out by communities of smallholder farmers. We evaluated genetic responses and the rate of inbreeding from alternative village sheep breeding schemes that were based on a survey of existing flock structure and breeding management in a sheep-barley system in Ethiopia. This survey showed that individual flock sizes were small, and that the majority of farmers practiced mixed grazing and uncontrolled mating of their flocks in communal grazing lands within villages. Here we evaluated within-village schemes (selection across flocks within a village) and across-village schemes (selection across villages) at different intensities of ram selection (i.e. proportions of rams selected, P). Our results showed that under within-village schemes, intensity of selection could not be increased (i.e. P could not be decreased below 0.149) when the rate of inbreeding was constrained to an acceptable level of 0.01, resulting in low genetic gain. The most optimal scheme was found to be across-village selection with at least three villages cooperating and P = 0.05. Our results also indicated that genetic gain from village breeding schemes with mass selection and BLUP selection is comparable. Village breeding schemes can make a significant contribution to the genetic improvement of livestock in Ethiopia and other developing countries. 相似文献
2.
Livestock provide a wide variety of goods and services that generate income and support the livelihoods of millions of poor people in the developing world. Natural and human selections have shaped existing livestock genotypes throughout the estimated 12,000 year history since the first animal domestication. The result, in many production systems in the developing world, is a livestock genotype adapted to its environment and capable of meeting the needs of smallholder farmers. However, this adaptation is unlikely to be optimal and the rapid changes currently affecting the livestock sector, including policy and market changes, movements of germplasm frequently involving the importation of exotic breeds, and the increasing impacts of climate change are affecting the livestock genotype-environment optimum. This is challenging livestock production systems of smallholder farmers. Current challenges include: high rates of loss of the diversity in livestock populations, rapid transformation in smallholder production systems requiring significant changes in genotypes and their management; increased demand for quality and safe foods; increased market competition in a globalizing economy; increased need for complex partnership arrangements in the ever-changing livestock commodity chain; and lack of adaptive capacity to respond to the rapid system changes. Underlying all these is the general lack of strategies for genetic improvement of livestock in smallholder systems and poor livestock infrastructure in developing countries. Opportunities include increased demand for livestock products — and hence potential market opportunities, and new technologies with potential to leap-frog breeding progress in developing countries. This paper analyses options for pro-poor livestock improvement in developing countries, with particular emphasis on the potential role that science – both old and new – will have, from understanding the social underpinnings to innovative technical solutions. It concludes that one of the highest priority interventions for the smallholder systems is the development of innovative approaches for the strategic use of appropriate genotypes from the available range of global breed resources. The analysis strongly suggests that the highest priority ‘breeding intervention’ should be the provision of appropriate genotypes in a sustainable manner, underpinned by a good understanding of what breed resources exist that have demonstrated potential, where else they could be used, and how they would be delivered to smallholders. Efforts to improve/refine breeding skills of smallholders should proceed in parallel. Institutional arrangements and enabling policies are critical for the success in identifying and applying appropriate genetic technologies, improving access to input services and facilitating access to markets in order to translate productivity gains into incomes. 相似文献
3.
Notter DR 《Journal of animal science》1999,77(1):61-69
Farm animal genetic diversity is required to meet current production needs in various environments, to allow sustained genetic improvement, and to facilitate rapid adaptation to changing breeding objectives. Production efficiency in pastoral species is closely tied to the use of diverse genetic types, but greater genetic uniformity has evolved in intensively raised species. In poultry, breeding decisions are directed by a few multinational companies and involve intense selection, the use of distinct production lines, and very large populations. In dairy cattle, the Holstein breed dominates production. Intensive sire selection is leading to relatively rapid inbreeding rates and raises questions about long-term effects of genetic drift. Key questions in management of farm animal genetic diversity involve the distribution of potentially useful quantitative trait locus alleles among global livestock breeds. Experiments with tomato, maize, and mice suggest that favorable alleles can exist in otherwise lowly productive stocks; this cryptic variation may potentially contribute to future selection response. Genetic improvement under relatively intense unidirectional selection may involve both increases in the frequency of favorable additive alleles as well as the progressive breakdown of homeostatic regulatory mechanisms established under the stabilizing selection that is characteristic of natural populations. Recombination among closely linked regulatory loci and new, potentially favorable mutations are possible sources of long-term genetic variation. A greater understanding of the potential that these alternative mechanisms have for supporting long-term genetic improvement and of genetic relationships among global livestock populations are priorities for managing farm animal genetic diversity. 相似文献
4.
K. Tindano N. Moula A. Traoré P. Leroy N. Antoine-Moussiaux 《Tropical animal health and production》2017,49(6):1187-1193
Urbanisation in developing countries entails deep changes in the livestock sector and the management of animal genetic resources (AnGR). Sheep breeding around Ouagadougou (Burkina Faso) illustrates these changes and the need to coordinate genetic improvement in general and the use of crossbreeding in particular. For this, it is important to understand breeders’ choices and improvement strategy, to accompany them within a national plan for AnGR management. In a context of missing market for breeding rams, a stated choice experiment was conducted with 137 farmers, together with a characterisation of herd management practices. This survey analyses farmers’ preferences for breeding rams, estimating their willingness to pay (WTP) for different traits (attributes). Their practices were characterised by a high reliance on natural pastures (82% of farmers) and a minority of crossbreeding (23%). The highest WTP was observed for disease resistance. However, the subgroup of farmers practicing crossbreeding showed a tolerance to high susceptibility. A strong preference for the white colour was revealed. Although significant, the influence of sheep body size on decision-making showed a lesser importance, again with a distinct behaviour in the subgroup practicing crossbreeding. These results illustrate the need to take account of the diversity of goals and preferences among smallholder sheep keepers to gain their adhesion to a coordinated genetic improvement framework. 相似文献
5.
6.
R.B. Land 《Livestock Production Science》1981,8(2):95-99
The merits of animal breeding are related to the rate of improvement which can be offered. Objectives however may alter particularly as a result of social change, so that improved local livestock may be left adapted to outdated conditions, thus emphasising the need for flexibility. Historically such flexibility and indeed much improvement has depended on the introduction of superior strains, previously selected by others, which happened to meet local requirements. The development of strains with divergent biological characteristics as a supplement to existing policies would increase genetic flexibility, could facilitate a faster genetic response and aid the rapid improvement of indigenous breeds. Such a policy would ensure the availability of appropriate genetic variation in the future and thus provide a positive complement to the passive conservation of “rare” breeds. 相似文献
7.
H Woelders J Windig SJ Hiemstra 《Reproduction in domestic animals = Zuchthygiene》2012,47(Z4):264-273
Many local breeds are currently at risk because of replacement by a limited number of specialized commercial breeds. Concurrently, for many breeds, allelic diversity within breeds declines because of inbreeding. Gene banking of germplasm may serve to secure the breeds and the alleles for any future use, for instance to recover a lost breed, to address new breeding goals, to support breeding schemes in small populations to minimize inbreeding, and for conservation genetics and genomics research. Developments in cryobiology and reproductive technology have generated several possibilities for preserving germplasm in farm animals. Furthermore, in some mammalian and bird species, gene banking of material is difficult or impossible, requiring development of new alternative methods or improvement of existing methods. Depending on the species, there are interesting possibilities or research developments in the use of epididymal spermatozoa, oocytes and embryos, ovarian and testicular tissue, primordial germ cells, and somatic cells for the conservation of genetic diversity in farm- and other animal species. Rapid developments in genomics research also provide new opportunities to optimize conservation and sampling strategies and to characterize genome-wide genetic variation. With regard to gene banks for farm animals, collaboration between European countries is being developed through a number of organizations, aimed at sharing knowledge and expertise between national programmes. It would be useful to explore further collaboration between countries, within the framework of a European gene banking strategy that should minimize costs of conservation and maximize opportunities for exploitation and sustainable use of genetic diversity. 相似文献
8.
K. Soini C. Diaz G. Gandini Y. de Haas T. Lilja D. Martin‐Collado F. Pizzi EURECA – consortium S. J. Hiemstra 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2012,129(6):436-447
Recognizing cultural diversity among local breed farmers is crucial for the successful development and implementation of farm animal genetic resources FAnGr conservation policies and programmes. In this study based on survey data collected in the EUropean REgional CAttle breeds project from six European countries, a typology of local breed farmers was designed and profiles for each of the farmer types were developed to assist these policy needs. Three main farmer types were constructed: production‐oriented, product and service‐oriented and hobby‐oriented farmers. In addition, seven subtypes were characterized under the main types: sustainable producers, opportunists, multi‐users, brand makers, traditionalists, pragmatists and newcomers. These types have many similarities to the ‘productivist’, ‘multifunctional’ and ‘post‐productivist’ farmer types. The typology not only reveals the high level of diversity among local cattle breed farmers in Europe, which presents an opportunity for the in situ conservation of animal genetic resources, but also a challenge for policy to meet the differing requirements of the farmer types. 相似文献
9.
The liberalization of European animal breeding legislation and an increasing diversity of equestrian sports have led to a constant rise in the number of horse breeds and breed registries. In addition to the trend towards more and smaller breed registries, there is another trend towards an international expansion of the bigger established sport horse breeds. Regional breeds, at least in smaller countries, may no longer be able to run an independent breeding programme. The typical horse breeder, in the future, will be a female and qualified in equestrian sports. Artificial insemination (AI) mainly with fresh or cooled-transported semen has become a major breeding tool, allowing breeders all over Europe to benefit from the best stallions of most breeds. New AI techniques such as low-dose insemination may remain restricted to individual stallions and also the interest of breeding programmes in sex determination of foals via semen sorting is limited. Embryo transfer and associated techniques, although allowed by most breeds, have not contributed significantly to genetic progress in European sport horses so far. A potential use of cloning may be to produce gonad-intact copies from geldings that have performed to a superior level. With a more open and international structure of horse breeding and increased use of AI, equine reproduction and biotechnology should be emphasized by veterinary curricula and continuing professional education programmes. 相似文献
10.
C McManus 《The Veterinary record》1991,128(5):100-102
Selection is the major tool used by breeders to improve the genetic quality of their livestock. Traditional methods of selection are well proven and useful in improving the economic merit of livestock. The performance of an animal is affected by its genetic quality and by the environment in which it is reared. While environmental improvement is expensive and requires continuous inputs, genetic improvement is cumulative and permanent, provided that selection is maintained. To select an animal on its genetic merit account must be taken of the environmental effects on its performance. Comparisons between the performance of animals on different farms or in different years are not valid unless they have genetic material in common. The speed at which genetic improvement is passed on to the rest of a population is affected by the variation and heritability of the traits being selected, the selection intensity and the generation interval. The deer population in the United Kingdom has a high degree of variation for important traits but the selection intensity is low and the generation intervals are larger than in other farmed species. Central performance testing, group breeding schemes and the use of artificial insemination are tools which will be important in the genetic improvement of farmed deer. 相似文献
11.
Molecular characterization of breeds and its use in conservation 总被引：3，自引：0，他引：3
The conservation of farm animal resources is important for coping with future breeding needs and for facilitating the sustainable use of marginal areas. The increasing availability of molecular markers for most farm animal species and the development of techniques to analyse molecular variation is widening our capacity to characterise the genetic variation of breeds. In this paper we review the most popular molecular markers used in conservation and animal breeding studies, the different measures of genetic diversity that they provide, and their application for managing within-breed genetic diversity and for setting between-breed conservation priorities. We also address the relationship between genomic and marker heterozygosity, the relationship between molecular and quantitative measures of genetic diversity, and the characterization of breeds based on non-neutral markers. 相似文献
12.
An international panorama of goat selection and breeds 总被引：2，自引：0，他引：2
The preservation of the biodiversity of animal breeds is an important condition to maintain the ability of animal production to adapt to the changing conditions of breeding and production systems in the future. The decrease of the number of animal breeds has been observed both for sheep, cattle and goats in relation with the standardisation and intensification of animal production systems.Goats are mainly concerned by the situation as they have the biggest increase in livestock numbers in 20 years. A global overlook of goats worldwide is showing a contradictory situation: On one hand, small but well organised sectors have developed in a few countries for milk and cheese, meat and fibre production. On the other hand, most of the goats are mostly still used for auto consumption of milk meat and skin or fibres in village herds. The present goat genetic situation is the direct consequence of this evolution with the high specialisation of a small number of selected and well characterised breeds for milk, meat and fibres and a majority of not well defined populations and local breeds, generally without selection schemes and organisation.A global panorama of the main families and breeds is presented. A special consideration is then pointed on the necessary financial and logistic conditions to achieve successively these selection objectives. After having observed that in many cases these conditions are not present, this report concludes by some proposals to control better the possibilities of success and express with more efficiency the genetic potentiality of this interesting species. 相似文献
13.
JA Long 《Reproduction in domestic animals》2008,43(S2):83-88
Today's livestock diversity originated from the wild ancestor species and was subsequently shaped through the processes of mutation, genetic drift, and natural and human selection. Only a subset of the diversity present in the ancestral species survives in the domestic counterparts. A 2007 report released by UN Food and Agriculture Organization ' The State of the World's Animal Genetic Resources ', compiled from surveys conducted in 169 countries, found that nearly 70% of the world's remaining livestock breeds live in developing countries. The UN report was presented to more than 300 policy makers, scientists, breeders, and livestock keepers at the First International Technical Conference on Animal Genetic Resources, held in September 2007 in Interlaken, Switzerland. The conference aims were to adopt a global plan of action for conserving animal genetic resources as its main outcome. In this paper, the current and potential contributions of reproductive and molecular biotechnology are considered as tools of conserving rare breeds of livestock. 相似文献
14.
绵羊是较早驯化的家畜之一，可为人类提供肉、毛、奶等产品，因而在我国畜牧产业中占有重要的地位。由于各地自然环境的差异和社会需要的不同，经长期的选择形成了数百个外表特征和生理习性各具特色的绵羊品种。羊角作为绵羊品种的特征性表型，承担着双重功能，发达的羊角不仅有利于公羊个体提高其在种群内的地位，拥有优先交配权，还可以有效抵御天敌的攻击，使群体免受捕食伤害；然而，随着规模化养殖的推广，羊角的存在已不利于舍内饲养管理，进而对绵羊品种的培育工作提出了新要求。目前，羊角虽在实际生产和品种培育工作中受到广泛关注，但其形态多样性及遗传调控机制的研究尚显不足。本文根据我国现有绵羊品种，对角的数量和形态、发育过程、遗传调控机制等方面的研究进行了综述，不仅能为后期鉴别绵羊羊角多样性的突变位点和主效基因提供参考，也可为绵羊的新品种培育奠定相关的理论基础。 相似文献
15.
目前,驴产业正在由短期育肥向繁育兼顾的新型可持续发展模式转变,同其他畜禽品种类似,驴产业的转型也是以扩大优良种群和提高品种质量为前提基础,而数量的增加和质量的提高都离不开良种繁育这一关键环节。然而,母驴繁殖力低是制约驴产业成功转型的主要瓶颈之一。驴繁殖力低不仅导致现有驴群的扩繁速度慢,存栏量与日益增长的皮、肉、奶的消费需求之间差距越来越大,而且使新品种的培育周期延长。已有研究表明,辅助繁育技术在提高母驴繁殖性能和改良驴的遗传性状等方面发挥重要作用,如同期发情、排卵控制、人工授精和胚胎移植等辅助繁殖技术可大幅提高母驴的繁殖能力;同时,微卫星标记技术、线粒体DNA测序技术、单核苷酸多态性研究和全基因组选择技术等分子育种手段也能够进一步加快驴的遗传改良进程。文章简要介绍了驴的生殖生理,系统阐述了同期发情、排卵控制、人工授精、胚胎移植、分子标记辅助育种和全基因组选择等辅助繁育技术在驴上的研究进展,并对未来研究方向进行了展望,以期对提高母驴繁殖性能提供借鉴,为开展驴分子育种研究提供有效线索。 相似文献
16.
畜禽遗传资源的保存对应对未来的育种需要和畜牧业的可持续利用是非常重要的。分子标记广泛应用于大多数畜禽品种及分子变异分析技术的发展,促进了分析品种遗传变异的能力。作者对用于度量畜禽遗传资源的群内遗传多样性评价方法及其在确定种内遗传多样性,以及保种方案中的应用进行了综述。 相似文献
17.
18.
Ilse Köhler-Rollefson H. S. Rathore E. Mathias 《Tropical animal health and production》2009,41(7):1061-1070
In South Asia, and throughout the developing world, the predominant official approach to livestock development has been improvement
of production by means of upgrading local breeds via cross-breeding with exotic animals. This strategy has led to the replacement
and dilution of locally adapted breeds with non-native ones. This has resulted in an alarming loss that has been estimated
by the Food and Agriculture Organization of the United Nations to amount to one breed every two weeks. Based on selected case
studies this paper argues that development strategies using locally adapted breeds and species are much more likely to benefit
livestock keepers whilst also maintaining domestic animal diversity and bearing a smaller ecological footprint. It also analyses
the rationale for “Livestock Keepers’ Rights”, a principle that grew out of the struggle of traditional livestock keepers
to retain control over their production resources, such as grazing areas and breeding stock, in the face of unfavourable policy
environments. 相似文献
19.
20.
Between-breed genetic diversity is classically considered as a major criterion to be taken into account when setting priorities for conservation of domestic animal breeds. However, it has been argued that methods based on the between-breed component of genetic diversity may not be optimal because they ignore the within-breed component of variation. The paper considers the most common methods used to evaluate those two components when genetic diversity is evaluated on the basis of genetic markers, and proposes to define an aggregate diversity combining linearly the two components. This implies defining for each breed (or population) its contributions to the between-breed and to the within-breed diversity. When defining an aggregate diversity, one can weight these contributions by FST and 1−FST, respectively, since the fixation index FST of Wright represents the proportion of the total genetic variation which is due to differences in allelic frequencies between populations. Such an approach is valid when the objective is genetic improvement by selection within a so-called “meta-population”. However, in a more general context of animal breeding, when heterosis and complementarities between breeds have to be considered, as well as adaptation to specific environments, more weight should be given to the between-breed variation. The proper weight to apply may require solutions adapted to each particular situation. In a long-term conservation perspective, priorities should also take into account the degree of endangerment of each breed. By combining diversity contributions and probability of extinction, a cryopreservation potential (or priority) may be estimated for each breed. The problem is illustrated on a sample of 11 European pig breeds typed for 18 microsatellite loci. 相似文献