Genomic strategies for optimal crossbreeding in African dairy cattle

This project will develop genomic strategies to optimise crossbreeding in livestock breeding programmes with focus on East African crossbred dairy cattle. Crossbreeding is the mating of individuals from different lines, breeds, or populations. There are three benefits of crossbreeding in livestock:

• Cross-bred animals perform better than purebreds because of breed complementarity,

• Cross-bred animals perform better than purebreds because of heterosis (hybrid vigour), and

• Cross-breeding protects breeders' intellectual property because production animals outperform their offspring.

Breed complementarity refers to the fact that a cross between breeds with different strengths has the potential to combine the strengths of its parents. In the East African dairy sector, which provides the context for this project, the goal is to develop a cross in cattle that combines the milk production of the Holstein with the tropical adaptation of the East African Zebu. Hybrid vigour is the tendency of a cross-bred animal to outperform its purebred parents. Cross-breeding protects the breeders' intellectual property because cross-bred production animals outperform their offspring, so farmers get better returns by buying production animals from the breeder than by breeding from production animals. An analogous example of the benefits of cross-breeding in the crop breeding practice is seen in maize which has seen a 6-fold increase in productivity since hybrid breeding was introduced in the 1930s.