Browsing by Person "Herold, Pera"

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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.
Untersuchung von Laktationsstruktur, Nutzungsdauer und Lebensleistung für die Entwicklung eines nachhaltigen Zuchtprogramms für Milchziegen im ökologischen Landbau
(2019) Wolber, Marie-Rosa; Herold, Pera
With increasing agricultural goat farming, also the goat breeding for dairy goat farms is becoming more important. As most dairy goat farms are managed organically, organic breeding comes to the forefront. The present work was created within the project GoOrganic. The project is intending the development of a sustainable, resource-efficient and ecological breeding program for dairy goats. Aim of breeding is a good lifetime performance with high quality components and robustness, especially in grazing systems. In the present work it was hypothesized that the sustainability of the breeding program is represented with a high lifetime performance. Lifetime performance is considered as a summary of the milk yield within a healthy and a long life. This hypothesis gave rise to two main objectives. One aim was to identify characteristics that represent lifetime performance. Another aim was to integrate the lifetime performance into the estimation of breeding value. This resulted in two hypotheses. It was assumed that the changed lactation structures, milking through and extended milking, does influence the lifetime performance and should be taken into account within the estimation of breeding values. Furthermore, it was assumed that the characteristics of lifetime performance are hereditary and can therefore be included in the genetic evaluation or being used within the framework of the ecological breeding program. Based on the health monitoring from the cattle sector, a health monitoring system for dairy goats was developed as part of the GoOrganic project. Observations and measures by farmers can be recorded. Subsequently, based on the collected health data, breeding values for the functional traits will be estimated. Due to the change in the lactation structure, it was necessary to consider phenotypically lactations of dairy goats. Underlying is the definition of a 240-day performance as standard lactation performance in the context of estimation of breeding value for dairy goats. Consequently, the genetic background of the altered lactation structures was investigated. The aim was to find out whether a breeding prolongation of the lactations is possible. Subsequently, the performance milk recording data were considered at animal level. It was examined which of the traits are suitable for the development of a breeding value for length of productive life and lifetime effectivity. The data analysis showed that the lactations of the dairy goats partially exceeded the standard performance of 240 days in milk and that the lactation length could be modified by breeding. As part of the estimation of breeding values, an alternative to the currently used milk yield within 240-day in milk performance should be determined in the future to achieve a more precise description of the lactation performance as the lactation yields of permanently milked animals are not implied and are not completely reproduced. The heritabilities of the persistence milk yield and milk yield (kg) were set in the low to medium range. Both the phenotypic and genetic correlations between persistence milk yield and milk yield (kg) were located in the high positive range. Thus, a breeding extension of the lactations is possible. A clear separation of the breeding aims between extended and not extended milking farms should also be considered. Heritabilities for length of productive life, and the effectivity per day in milk were overall in the middle range. The traits of length of productive life and effectivity per day in milk are possible to breed. The milk yield in the first 120 days in milk in the first lactation correlated genetically positively with the length of productive life, lifetime effectivity and with the milk yield per day in milk. Lifetime effectivity was highly correlated with length of productive life and milk yield per day in milk and should therefore be given a more thorough consideration when developing a breeding value for length of productive life and lifetime effectivity. With the present work the basis for development of a breeding value for length of productive life and lifetime effectivity could be demonstrated. Overall, the basis for the development of a sustainable breeding program for dairy goats in organic farming could be represented.