Abstract The need to “balance” maternal and terminal traits only exists if a producer intends to both sell terminal animals and retain replacement females from the same matings. For a sizable fraction of commercial cow-calf producers this is indeed the case. This balance can be reduced to emphasizing traits based on their economic importance to the respective enterprise. At a high-level the process is simple: 1) develop a breeding objective, 2) develop a breeding system and select breeds, 3) identify an economic selection index to use in ranking selection candidates, and 4) inform the previous steps with updated herd performance and economic parameters. A web-based decision support platform, iGENDEC, offered through the Beef Improvement Federation enables the user to develop customized economic selection indexes that aid in developing an economically balanced approach to emphasizing both maternal and terminal traits. To capitalize on decision support tools like iGENDEC producers need to have objective data that describes the current performance of their cows and calves and historic averages of economic parameters such as the pricing grids for calves sold and variable cow costs. In addition to current herd performance and average economic parameters, producers should also contemplate the notion of a planning horizon. A planning horizon can be thought of as the length of time, in years, to account for costs and revenue associated with a genetic selection decision. Some traits are expressed later in life, and generally the traits expressed later in life are maternally oriented (i.e., reproductive longevity, mature weight). If planning horizons are relatively short (less than 5 years) the traits that will be emphasized are those that can be expressed more frequently within that time period such as calf growth and carcass merit. If planning horizons are longer (i.e., 20 years or greater) then more maternally oriented traits can be expressed and thus contribute to profitability of an enterprise. Consequently, selection for profit in the short-term will inherently focus on terminal traits. In order to achieve balance between terminal and maternal traits, a longer-term view of profitability is required. It is important to note that a “balance” between terminal and maternal does not necessarily mean absolute equality in terms of the degree with which they are emphasized in an index. Economics dictate the balance, and in traditional beef systems whereby only a relatively small fraction of replacements are retained and the balance of heifer calves are sold along with the steer mates, weight traits remain proportionally more important particularly when ownership is retained through the finishing phase. Exceptions to this generality can exist depending on current reproductive performance of the cowherd.
Matthew L Spangler (Wed,) studied this question.