Technological progress in animal production in the last 30 years has been substantial in some ways, negligible in others. On the one hand, livestock production per animal unit of breeding stock has shown gains of the same order as those in crop production per acre of land. But on the other hand, aggregate livestock production per unit of feed has shown little improvement. Progress has followed, in the main, the path of increased physical efficiency per head rather than that of increased physical efficiency in feed conversion. What are the reasons for this disparity in rates of improvement in animal production per head and per unit of feed? Is it real? If so, will it persist? Why is it that significant advances in animal breeding, nutrition, and sanitation are not reflected in available data on feed conversion? These and many other related questions need to be answered. In this paper the authors analyze several aspects of economic effects of the apparent lag in feeding efficiency.