Project Number: 8042-31000-101-08-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Apr 1, 2013
End Date: Mar 31, 2016
The objective of this project is to use gene network analysis to identify core genetic modules associated with dystocia (calving difficulty) in three breeds of U.S. dairy cows that have different phenotypes (low, moderate, and high rates of dystocia). Currently there is little understanding of the genetic mechanisms that drive differences in dystocia rates. The agreement will greatly improve our understanding of the genetic architecture of calving difficulty, and will help to better understand why some breeds have a problem in this area and others do not.
Previous research by ARS has identified a genetic marker on chromosome 18 that is associated with calving difficulty in Holsteins, but not Brown Swiss or Jerseys, and no genes with large effects on dystocia have been identified in the Brown Swiss breed. This implies that non-additive gene action is responsible for much of the differences observed between breeds. A systems biology approach based on the adaptive weight matrix (AWM) technique will be used within breed to identify gene pathways that are enriched with SNP having statistically significant effects on dystocia. Data also will be polled into a single data set and the AWM analysis repeated. Gene networks common to all breeds and the pooled dataset can plausibly be said to represent fundamental modules controlling the phenotypic expression of dystocia. Genetic evaluations for Jersey calving ease are not routinely computed, but will be calculated from the national dataset by ARS. The Cooperator and ARS will jointly design the experiment. The methods will be applied by the Cooperator to the data provided by ARS. Results will be interpreted and prepared for publication by ARS and the Cooperator.