Genetics and breeding of Taurine-Indicine crossbred dairy cattle

This project will study the genetics and breeding of Taurine-Indicine crossbred dairy cattle through data analysis, modelling, and stakeholder engagement.

Taurine-Indicine crossbred cattle is used in many countries to harness the fitness of Indicine breeds and the productivity of Taurine breeds. In this project, we will focus on the Girolando population that represents 80% of the Brazilian dairy herd. Foundation for this population is the locally adapted Indicine dairy breed Gyr. Gyr cows are crossed with the productive Taurine dairy breed Holstein. These crossbred Girolando cows are further crossed with one of the parent breeds or crossbreds in an ad-hoc manner. The ad-hoc crossbreeding is causing large variation in adaptability and productivity.

The project will be performed in three stages:

• First, we will analyse genomic data from a population genetic perspective to quantify differences between the parent breeds and the genetic composition of crossbred animals. This work will make use of recent advances in population genetics to infer whole population trees with recombination across the two cattle genomes.
• We will then expand the population genetic analyses with quantitative genetic analyses of dairy performance under various Brazilian environments and management practices. This will quantify the magnitude of additive and non-additive genetic variation and genotype by environment interaction as well as map this variation to regions of the two cattle genomes.

• Finally, we will leverage the previous steps to build a digital twin (modelling / stochastic simulation) breeding programme of the Girolando population and evaluate various breeding strategies in collaboration with stakeholders. The aim will be to develop a strategy for continuous matching and improvement of adaptability and productivity in Brazilian environments. This will use selective breeding and mating strategies based on phenotypic and genomic information.