Regions of the Genome Associated with Mid-Lactation Feed Efficiency in Dairy Cattle

and Implications Regions of the genome associated with variation in feed efficiency and dry matter intake were identified using data from 3306 Holstein cows from Europe and North America. For feed efficiency, regions that explained the most variation were located on chromosomes 18, 5, and 3. For dry matter intake, top regions were 26, 5, and 25. For both traits no one region explained more than 2.8 percent of the total genetic variation. From these results we conclude that feed efficiency and intake are genetically and biologically complex traits that are impacted by many factors and the exploitation of no one particular gene will generate large genetic gains in these traits. Introduction Increases in feed efficiency are continually sought in part because of their potential for economic and environmental improvements. While management and feeding practices have been employed to improve the feed efficiency of the dairy cow, genetic improvements have been minimal, largely due to the equipment and labor demands of recording feed intake on large numbers of individual cows, which is necessary to gain meaningful insights to quantitative traits. Consequently, collaboration between United States and European researchers was established in order to pool data for the exploration of the genetics of feed efficiency. The goal of this study was to identify regions of the genome associated with feed efficiency and dry matter intake (DMI).