Comparison of methods for admixture and heterosis mapping in crossbred cattle populations

Abstract

Crossbreeding is a promising strategy to overcome the global challenge of supplying food to over 9 billion people by 2050. Crossbred animals usually combine favorable traits from their purebred ancestors, and in many cases their performance exceeds the parent average. This phenomenon, known as heterosis or 'hybrid vigor', is a genetic dominance effect, best expressed when the parental alleles differ drastically in frequency. Therefore, a major challenge in breeding programs exploring crossbreeding is to predict dominance deviations from average effects encoded by conventional breeding values. Currently, little development has been observed in cattle genomics regarding strategies for admixture and heterosis mapping, and this is a priority in South America, Europe and West Africa, where different types of crossbreeding strategies are emerging to increase productivity together with fitness. Of special interest, beef and milk production must be sustainable and coupled with satisfactory heat tolerance, fertility and disease resilience. Using real and simulated genomic and phenotypic data, the present proposal aims at evaluating methods for admixture and heterosis mapping. Scenarios matching crossbreeding carried out in Europe for Swiss Fleckvieh cattle, in South America for Girolando cattle and in West Africa for trypanotolerant crosses will be evaluated.