Crossbreeding in dairy cattle: novel breeding tools for sustainable dairy and beef production
For several decades, crossbreeding has been a common practice in some production animal species, especially pig and poultry. The interest of crossbreeding in dairy cattle has increased during the last few decades, but purebreeding is still the major strategy of breeding. This purebreeding – especially within the Holstein breed - has led to problems, such as reduced fertility, health and survival, in many countries including Sweden. In other countries, such as New Zealand, crossbreeding has become a main strategy to avoid those problems. New technologies, such as sexed semen and genomic breeding values available at an early age, and use of beef semen give rise to new possibilities for crossbreeding of dairy breeds.
The overall aim of this PhD project is to investigate and develop genetic and management tools for crossbreeding strategies in Swedish dairy cattle. The first years of the project will focus on SimHerd simulation studies of economic and genetic consequences of different crossbreeding strategies. A part of the simulations include scenarios using a native breed (Swedish Polled Cattle) in a crossbreeding strategy for conservation purposes. Another part of the simulations includes scenarios with commercial dairy breeds (Swedish Holstein and Swedish Red) with emphasis on use of sexed semen and beef semen. The latter group of scenarios will be further used to simulate the genetic consequences of crossbreeding and use of other bio-techniques considered, such as genotyping, genomic breeding values and embryo transfer. The last part of the PhD project will investigate and develop possibilities for genomic breeding values on crossbred performance in dairy cattle.