The production process of transforming a 600–700 pound feeder steer into a slaughter animal typically requires four to six months. Conceptually, there should exist some relationship between the prices of feeder calves and slaughter cattle prices. In one view, since the feeder calf constitutes the costliest input in the production of the slaughter animal, the prices of fed cattle should be temporally connected to the cost of the feeder animals. This view suggests that feeder calf prices should lead slaughter prices by the length of the production process (Trierweiler and Hassler). In another view, the price of feeder calves is determined by the interaction of the supply of and derived demand for feeder cattle by feedlot operators. It is presumed that the derived demand for feeder cattle is related to feedlot operators' expectations of future fed cattle prices. If their expectations are strongly influenced by current fed cattle prices, then a relationship is suggested whereby slaughter and feeder prices vary concomitantly.

Prior to the 1970s, energy accounting was the primary domain of physical scientists or engineers. The world of thermodynamics, rigorous concepts of energy ratios and entropy, seemed safe within their laboratories where, for example, the relative energy efficiency of solid and liquid fuels was assessed for powering an industrial heating system. This apparent orderly state of affairs—measurement primarily in controlled laboratory conditions—seemed to change abruptly in 1973 with the OPEC oil embargo. Energy accounting became the chore, if not the mission, of a myriad of scientists, engineers, businessmen, bureaucrats, and politicians. Understandably, the journals and other periodicals of our profession now abound with proposals on how to measure energy and how to employ these measures in making decisions and developing government policies.

The most important issue raised in the comment by Bradford involves the problem of how to handle the fact that, although the logical period for accounting for energy use on the farm is one year, farm machinery is typically used over a period of several years. No solution to this problem will be entirely satisfactory, and the alternative offered by Bradford has its own difficulties. Nevertheless, the Bradford alternative is worth trying, and this response to the comment will consider briefly his proposal.