Producer uptake

Abstract

The Bovine Respiratory Disease Complex Coordinated Agricultural Project (BRD CAP) is a 5-year USDA-funded Coordinated Agricultural Project to develop genetic markers associated with bovine respiratory disease (BRD) to identify cattle that are less susceptible to BRD. Ultimately the aim of this project is to integrate predictive markers for BRD susceptibility into genetic tests and national cattle genetic evaluations. Work is ongoing to identify regions of the genome associated with BRD susceptibility in both dairy and beef cattle. Initial results have identified multiple genomic regions that were significantly associated with BRD susceptibility. Genomic information has typically been integrated into genetic evaluations based on linkage disequilibrium (LD) between single nucleotide polymorphism (SNP) markers and the causative mutations affecting economically relevant traits. This has been successful to develop selection within breeds in the dairy cattle industry, but has been more problematic in the beef cattle industry due to the presence of numerous breeds and the importance of crossbreeding in the commercial cattle population. LD between markers and QTL has not be consistent across breeds, and so markers that were identified in 1 breed were frequently uninformative in other breeds. However, the sequencing of a large number of animals has opened up the possibility of identifying the actual SNP variations that are causing genetic variation and performing sequenced-based genomic selection of cattle. There are several advantages associated with this approach including persistence of the marker affect across generations, and an increased likelihood that causative polymorphisms will be similarly associated with variation across multiple breeds. It is envisioned that by imputing the genotypes of reference animals collected by the BRD CAP up to full sequence and further fine mapping and analyses, that the causative genetic variants associated with BRD susceptibility will be identified, and that inclusion of these markers on genotyping platforms will provide a reliable selection criterion to enable for the selection of both beef and dairy cattle that are less susceptible to BRD.