By Dr. Deb Hamernik, ASAS President
Sept. 12, 2016 – Dr. Christian Maltecca gave an invited presentation, “The important and often forgotten role of managing genetic diversity” at the 67th Annual Meeting of the European Federation of Animal Science (EAAP) in Belfast, Ireland on August 29 – September 2, 2016. More than 1,500 people attended the EAAP annual meeting.
Dr. Maltecca is interested in improving economically relevant traits in dairy cattle through the use of quantitative and molecular methods. Use of genomic markers in animal breeding is an active area of research. Genomic markers have been incorporated in selection decisions as a tool to control inbreeding in many species, including dairy cattle. Additional research is needed to identify the optimal way to use genomic markers to select genetically superior animals and manage the genome of a specific population of animals that is being selected for complex quantitative and/or fitness traits such as pounds of milk or meat and/or number of progeny, respectively.
Dr. Maltecca’s presentation focused on the three pillars of managing genetic diversity, including: 1) understanding the basis and consequences of genetic diversity, 2) managing the population by controlling its effective size, and 3) optimizing genetic variability through specific mating plans. Dr. Maltecca’s team conducted simulation studies with their recently developed Geno-Driver tool that allows for a wide range of selection strategies to be evaluated in the presence of a fitness trait. A run of homozygosity (ROH) is an alternative metric that characterizes long stretches of inbreeding. Some regions of the genome have a high frequency of ROH and these are linked to a reduction in genetic diversity as well as negative effects on fitness traits. Crossbred animals have persistent stretches of shared haplotypes that can be identified based on long (>5Mb) ROH.
Dr. Maltecca indicated the need for targeted approaches to manage genetic diversity in livestock as well as the need to understand genomic diversity and genomic load. Using genomic information to constrain relationships results in the maintenance of greater genetic diversity. Use of a ROH-based relationship shrinks long homozygous stretches to a greater extent than the traditional SNP-based approach. Scientists should place a value on maintaining genomic diversity in livestock–this is one of the first, clear opportunities to move toward precision breeding.
Christian Maltecca is Associate Professor, Department of Animal Science, North Carolina State University.