Browsing by Subject "Lactation persistence"

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    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.