Balancing genetic gain and diversity in dairy cattle breeding schemes in the genomics era

The overall objective of the project is to improve sustainable breeding schemes that maximises response to selection for efficiency, animal health and climate impact while maintaining genetic diversity ensuring future selection potential. Dairy cattle breeding schemes are challenged by a long delay from selection decisions until responses are observed in lactating daughters of more than 4 years. Further dairy production is largely based on purebred animals, and thus production is directly affected by inbreeding in contrast to species like poultry and pigs where production animals are crossbred. Optimal contribution selection (OCS) is a well-known method for finding the right balance between the rate of genetic gain and the loss of diversity. By increasing genetic gain in dairy cattle given such restrictions, we will increase profit for the farmer, increase animal welfare, reduce climate impact with the lowest possible loss of diversity. To obtain the overall objective, the project addresses three research questions. First, finding genomic measures of inbreeding that are sensitive to changes in the breeding scheme, and thus allows early detection of increased rates of inbreeding. Secondly, quantifying the costs of inbreeding by a meta-analysis of inbreeding depression for all traits in the breeding objective. Thirdly, developing strategies for management of genetic diversity in Nordic dairy populations with multiple sequential selection stages, based on pedigree and/or genomic marker information.

This project is divided into three work packages:
WP1. Early indicators of changes in rates of inbreeding
WP2. Cost of inbreeding
WP3. Management of diversity in a multi-stage breeding scheme using OCS