Browsing by Subject "Zuchtwertschätzung"

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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.