Changes in livestock systems
3.5. Chickens
he breeding and production of this species is the most specialised and industrialised of all animal species. It is showing similarities with plant breeding and production. At a global level only a very few multinationals are active selling highly specialised hybrid layers and broilers. he number of chickens increases very fast at the global level, mainly due to active marketing by the layer and poultry industry. In developing countries the substantial role of chickens in small-scale farming, and the preference of local people for meat from local chicken breeds will stimulate the use of these local breeds in the future. In the developed world many people keep chickens as a hobby, which maybe an opportunity for conservation. Artiicial reproduction techniques are well developed, but cryoconservation of embryos or primordial germ cells still has to be developed.3.6. Horses
In the past, horses were mainly used for draught and transport. he onset of the mechanisation in transportation and later on in agriculture has meant that in many parts of the world horses are bred almost entirely for hobby and sport purposes. It develops itself as an industry in which hobbyists play an important role. he large variety in purposes may stimulate the maintenance of a wide genetic diversity within the species. However, in general, the genetic diversity within horse breeds is threatened by the wide use of a few popular stallions. he “heavy” breeds, originally bred for draught purposes, are threatened. In some countries they are still kept for meat production. Artiicial reproduction techniques including cloning and cryoconservation techniques are very well developed in this species, facilitating conservation.3.7. The threat of genetic erosion
From the former subsections it can be concluded that the threat of genetic erosion difers between the species. At the global level the threats are of little importance in goats and most severe in pigs. In pigs, chicken and cattle only a few breeds or lines are developed towards high-output breeds itting in high-input systems. In this process many breeds are set aside from the food producing livestock systems. hese breeds will be faced with extinction unless new functions for these breeds are found. his is a real threat for the genetic diversity within species. In farm animal species a substantial amount of genetic diversity exists within the breeds chapter 3. In commercial populations of cattle, pigs and chicken this diversity may be threatened by applying high selection intensities.Chapter 1. Introduction
Parts
» utilisation and conservation of farm animal genetic resources
» Challenges for food production in livestock systems
» Changes in livestock systems
» Cattle Consequences for the use of species and breeds
» Introduction utilisation and conservation of farm animal genetic resources
» Opportunities to meet future market demands
» Insurance against future changes in production circumstances
» Insurance against the loss of resources with a high strategic value
» Cultural and historic reasons
» History of initiatives to stop genetic erosion at global and regional levels
» Threats Opportunities and threats for farm animal genetic resources
» Conservation methods to be applied
» National governments Stakeholders for in vivo and in vitro conservation programs
» Objectives in conservation and utilisation of farm animal genetic resources
» Techniques Strategies for moving from conservation to utilisation
» Options for utilisation of self-sustaining local breeds
» Strategies for moving from conservation to utilisation
» Cryoconservation Strategies for moving from conservation to utilisation
» Costs Strategies for moving from conservation to utilisation
» Making the decision Strategies for moving from conservation to utilisation
» Introduction What is genetic diversity?
» Sub-populations and evolutionary forces
» The use of pedigree for measuring diversity
» The impact of DNA information
» Genome-wide patterns of diversity
» Measuring changes in diversity
» Relating diversity measures to F and ΔF
» Conclusion What is genetic diversity?
» Genomics reveals domestication history and facilitates breed development
» Marker and sequence information
» Detection of selection How have the events in breed history modified the genetic variation?
» Prediction of heterosis using genetic distances
» Conclusions Genomics reveals domestication history and facilitates breed development
» Why measure genetic diversity?
» Genetic distances Genetic distances, F-statistics and kinships
» Measuring genetic diversity in farm animals
» Weitzman diversity Weitzman and Core set diversities
» Genetic distances, kinships and conservation decisions
» Concluding remarks Measuring genetic diversity in farm animals
» Introduction Selection of breeds for conservation
» What are the objectives of a conservation effort?
» Is the risk-strategy efficient for the selection of breeds?
» Is the maximum-diversity-strategy efficient for the selection of breeds?
» Selection of breeds for conservation
» Is the maximum-utility-strategy efficient for the selection of breeds?
» What are the practical aspects?
» Inbreeding and inbreeding rate
» Genetic contributions Genetic contributions and inbreeding
» Optimum designs Minimising ΔF in conservation schemes
» Genetic contributions and inbreeding
» Optimum contributions: The problem
» Predicting ΔF Genetic contributions and inbreeding
» Guidelines for best practice
» The effective population size
» Operation of conservation schemes
» Cryo-conservation schemes Operation of conservation schemes
» General aspects Integrating live and cryoconservation
» Cryo-back-up live conservation schemes
» Existing global regulations Practical implications of utilisation and management
» Practical implications of utilisation and management
» An example of a national action plan for utilisation and management
» Economic considerations Practical implications of utilisation and management
» Utilisation and conservation of genetic diversity
» Monitoring role for the national managers
» Sustainable breeding schemes Practical implications of utilisation and management
» Future policies for animal genetic resources
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