Browsing by Subject "Zuchtprogramm"

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Entwicklung und Etablierung eines innovativen Zuchtwertschätzverfahrens für lokale Rinderrassen in Baden-Württemberg
(2020) Kohl, Sebastian; Herold, Pera
Over the last decades, cattle breeding schemes that used truncation selection provoked high inbreeding rates and were perceived increasingly critical. Reasons are the inefficient conversion of genetic variance in genetic gain and an increased risk of inbreeding depression (Falconer and Mackay, 1996; Woolliams et al., 2015a). A solution was found by Meuwissen (1997) by introducing Optimum Contribution Selection (OCS). OCS facilitates the maximization of genetic gain meanwhile restricting inbreeding rates to predefined levels. Wellmann et al. (2012) extended the existing OCS approach by two components: Migrant contributions and native genetic variance of the breed under observation. The resulting advanced OCS (aOCS) facilitates the implementation in regional breeds that have been crossbred with commercial breeds for upgrading reasons. Basic research has already been carried out (Wang et al., 2017a; b). The objectives of the underlying project were (I) a comparison of OCS approaches to be implemented in Vorderwald cattle by underlying population parameters following Hartwig et al. (2013). (II) A feasibility study to give empirical prove of the applicability of the chosen OCS approach in Vorderwald cattle. The main focus was on the costs of implementing OCS in Vorderwald cattle. These were contrasted with the benefits. (III) The development of strategies to implement an OCS approach in connection to the breeding value estimation at the Landesamt für Geoinformation und Landentwicklung Baden-Württemberg. The development of routine applications was paramount here. (IV) The development of a suitable breeding scheme that fits a proportion of 50 % natural mating in the actual Vorderwald population. Chapter 1 is an opinion article about financial, structural and social obstacles that impede the implementation of OCS in real breeding schemes. This chapter is mainly related to small scale cooperative breeding schemes of Germany, since this is a common organizational structure of regional breeds. Chapter 2 is a feasibility study. On basis of the identified obstacles of Chapter 1, a concrete and easy to implement breeding scheme will be developed. A stochastic simulation will be carried out, to reveal flaws in the developed breeding scheme and aOCS approach. Additionally, results of the stochastic simulation are directly comparable to real data. Chapter 3 is an extension of the feasibility study of Chapter 2 and proofs the feasibility of the developed breeding scheme under actual conditions of the Vorderwald cattle breed. Migrant contributions to the Vorderwald cattle breed reached 61 % in 2014. Thus, the aOCS approach was modified to test for possibilities of reducing this level. The thesis will end with a general discussion. Recommendations will be given, how to implement the developed breeding scheme of Chapter 2 in Vorderwald cattle and comparable breeds.
Optimising breeding programmes with local pig breeds in North Vietnam considering functions of pigs for smallholders and logistic determinants
(2009) Rößler, Regina; Valle Zárate, Anne
Due to an increasing national demand for pig meat products in Vietnam, national development incentives focus on the intensification of the pig production. Still, the majority of the national pig herd is kept on smallholder farms. For a successful integration of smallholders into a market-oriented pig production, numerous constraints have to be overcome. One possibility is the development of village breeding programmes. This study uses an innovative approach, combining an institutional analysis of the pig breeding organisation and deterministic modelling to evaluate the technical appropriateness as well as organisational feasibility of alternative smallholder breeding schemes with the aim to identify an appropriate design of village breeding programmes for different smallholder pig production systems in Northwest Vietnam. In concluding, heterogeneous breed and trait preferences for local pig breeds of smallholders in different pig production systems have to be considered for the successful implementation of village breeding programmes. In addition, measures have to be adopted to improve factors that increase the genetic gain and to decrease high breeding costs. For the latter, a simplification of the currently complex and research-oriented performance testing scheme is recommended. The integration of smallholder pig breeding into regional and national structures is necessary to ensure the sustainability of village breeding programmes. Stratified crossbreeding schemes linking villages in different production systems together with the establishment of breeding cooperatives at village level and short food supply chains could help strengthen the currently weak links of smallholders to other breeding institutions and integrate several villages into a producer cooperative. Thus, small pig breeding populations could be enlarged and smallholders, particularly those in remote villages with poorly developed infrastructure, could be integrated into existing regional value chains for local pig meat products. Yet, limited financial and technical capacities of smallholders require the support from the government, particularly in the implementation phase. Implemented breeding programmes should be as simple as possible in order to reduce the risk for smallholders.
Optimizing the development of seed-parent lines in hybrid rye breeding
(2001) Tomerius, Alexandra-Maria; Geiger, Hartwig H.
In hybrid rye breeding, seed-parent and pollinator lines are developed from two divergent gene pools. Line development comprises selection for line performance per se followed by selection for combining ability to the opposite gene pool. Cytoplasmic-genic male sterility (CMS) is employed as hybridizing mechanism. This study deals with model calculations aiming to optimize and compare alternative schemes of seed-parent line development in hybrid rye breeding on the basis of their expected selection gain per year in an index comprising the most important breeding objectives. Prediction of selection gains rests on current estimates of quantitative-genetic and economic parameters. The schemes are optimized for the number of candidates, testers to assess testcross performance, test locations, and replicates at the individual selection stages. Optimization is carried out assuming a fixed annual budget. Five schemes are investigated which differ in the basic genetic material assumed, in the type of test units and the number of selection stages for line and testcross selection, and in the length. The standard scheme employs second cycle material. First, S2-lines are evaluated per se. Selection for combining ability is then carried out at two stages employing testcross progenies of the CMS analogues of the candidate lines in backcross generations BC1 resp. BC2. The first alternative scheme employs an additional stage of BC1L-testcross selection. Another scheme is suited for developing seed-parent lines from broader-based population material. In addition to these 'conventional' methods, a scheme using doubled haploid lines is investigated as well as a scheme in which testcross progenies are produced by means of a gametocide instead of CMS. The optimum dimensioning and relative efficiency of the schemes is investigated for various genetical and economical situations.