Larger dairy cows don’t necessarily mean they will feed efficiently. Size and yield in dairy cows are not genetically correlated, says Lou Armentano, a University of Wisconsin dairy nutritionist.
Source: Dairy Herd Management, December 8, 2016.
But we are currently selecting for big cows, reducing positive [genetic] pressure on yield while selecting against feed efficiency. This is a lose-lose scenario.” Bigger cows take more feed to reach their mature body size and more feed to maintain that body size once they mature. As a result, feed efficiency drops over the lifetime of the animal.