Genetics of juvenile health and survival in dairy cattle

Realizing the economic and socioeconomic benefits of functional traits, i.e. traits increasing efficiency by reducing input costs, more and more countries have started to include such traits in the breeding goals for cattle. Among the functional traits frequently being recorded and evaluated in many countries are reproductive traits, persistency, milkability but also longevity to account for overall fitness. However, so far only Scandinavian countries have nationwide recording schemes for direct health traits by diagnosis data while other countries only record auxiliary traits to describe the health status. The focus is generally on lactating cows rather than on young breeding stock. In breeding programs, only survival data of the calves` life first 24 or 48 hours, reflecting the trait stillbirth, have been taken into account while their health status or survival until start of productive life has been neglected. Utilizing data from Austrian and Danish national cattle data bases, survival and health of juvenile cattle originating from specialized dairy and dual purpose breeds will be evaluated. The overall aims of this project are (1) to gain knowledge regarding juvenile health and survival in dairy cattle, (2) to increase the welfare of the animals as well as the consumer acceptance, (3) to increase the farmers` profit, (4) to monitor the health status and survival of juvenile cattle in Austrian and Danish dairy populations, (5) to develop methods for analysing health and survival traits in juvenile dairy cattle, (6) to calculate genetic parameters for health and survival traits in juvenile dairy cattle, and (7) to provide a basis for developing breeding value estimations for health and survival traits in juvenile dairy cattle. To achieve these aims, available survival and health data will be thoroughly evaluated by a detailed analysis of environmental effects, possible additional sources of information and periods for the definition of traits and trait groups as a first step. Comparing linear and threshold models as well as Survival Analysis will be a central point for the genetic analysis of both, survival and health traits. Another crucial part of this project will be the adaptation of the computer program Survival Kit used for Survival Analysis to account for a time-dependent sire effect. The proposed project has a high potential to set the grounds for a new methodology within Survival Analysis, for opening a new field of research with regard to health traits in juvenile cattle and for successful application in cattle and other domestic animals. As it brings together theoretical and applied research, the candidate and the involved home institution will be at the forefront of an emerging field, leading to an increased international recognition and probably to a further expansion of this research discipline.