Precision Crossbreeding of Livestock for Biomedicine and Food

Natural and artificial selection have resulted in a tremendous variety of adaptive and purpose-bred traits that have fed humanity since before the Neolithic Revolution. Underpinning this phenotypic diversity is tremendous genetic value for meeting contemporary societal needs in food and fiber production. Often this value is segregating only in isolated livestock populations, or bottlenecks imposed by geography, climate and culture has resulted in the loss of valuable genetics. Increasing the frequency of preferred alleles within a breed by limited introgression is a method to introduce economically important variants into new populations; however, this can also inadvertently increase the frequency of deleterious recessive alleles due to identity-by-descent effects. Despite the value that cross-breeding and introgression can provide, crossbreeding dilutes purpose-bred genetics that have taken centuries to assemble through intense selection. Therefore, we have developed gene editing deployment strategies to eliminate deleterious alleles accumulated by inbreeding, and to introgress beneficial alleles into naive breeds, bypassing expensive, multigenerational breeding programs. Precision crossbreeding by non-meiotic allele introgression will accelerate efforts to enhance genetic merit, and allow rapid incorporation of traits intended to improve animal well-being and agricultural sustainability in the face of global climate change and a growing world population.