A systems approach to integrating genetics , nutrition , and metabolic ef

The role of the dairy cow is to help provide high-quality protein and other nutrients for humans. We must select and manage cows with the goal of reaching the greatest possible effi ciency for any given environment. We have increased effi ciency tremendously over the years, yet the variation in productive and reproductive effi ciency among animals is still quite large. In part this is because of a lack of full integration of genetic, nutritional, and reproductive biology into management decisions. However, integration across these disciplines is increasing as biological research fi ndings show more specifi c control points at which genetics, nutrition, and reproduction interact. An ordered systems biology approach that focuses on why and how cells regulate energy and N use and on how and why organs interact by endocrine and neurocrine mechanisms will speed improvements in effi ciency. More sophisticated dairy managers will demand better information to improve the effi ciency of their animals. Using genetic improvement and proper animal management to improve milk productive and reproductive effi ciency requires a deeper understanding of metabolic processes during the transition period. Using existing metabolic models, we can design experiments specifi cally to integrate new data from transcriptional arrays into models that describe nutrient use in farm animals. A systems modeling approach can help focus our research to make faster and large advances in effi ciency and show directly how this can be applied on the farms.