Introduction

Defining economic breeding objectives for pork quality traits can become a difficult task. Not only do the various segments of the U.S. pork chain have different perceptions and requirements of quality these definitions of superior quality can in certain cases be antagonistic. In addition, the income and expense associated with quality measures are not currently observed at the farm level. The inability to measure meat quality in the live animal and the difficulty associated with routine carcass measurement also limits the opportunity for meat quality measures to be routinely included in the breeding objective.

Economic and Production Models

The objective of each firm in the pork chain is to maximize profit subject to production constraints and consumer demand. Individual firms are assumed to be unable to affect demand or input prices. They are left with the choices of what quality and quantity of product to produce and which inputs to use to produce that product set. Production technology, consumer demand, and input prices determine the firm’s derived demand for each input. Derived demand for genetic stock is defined by the change in profit that occurs with a change in the quantity/quality of genetic stock used.

Current breeding objectives for post-weaning selection include both growth and carcass traits. These traits include feed conversion ratio, days to 250 lb, backfat depth measured at the tenth rib and loin muscle area measured at the 10th rib. These breeding objectives apply to the farm level side of the production diagram (Figure 1). To evaluate processor and consumer needs as well as farm level needs the entire production model should be considered. Potential muscle quality measures for consideration in breeding objectives include ultimate pH, tenderness, intramuscular fat, water holding capacity and color. Other relationships to be considered are the amounts of fresh and processed product. Consumer definitions of quality apply primarily to fresh product. Consumer definition of quality in fresh product also differs between retail and foodservice purchases (e.g. intramuscular fat). Processed product quality is defined by the slaughterer/processor.

Economic Values and Demand

Economic values of traits are changes in profit associated with a marginal change in individual traits. The economic values for growth traits are calculated from the prices of feed and time-related inputs (labor, facilities, utilities, etc.). The economic values of carcass traits such as backfat depth, loin muscle area, and water holding capacity are calculated from the price of wholesale pork products, the costs of carcass processing, and the proportion of each type of saleable product produced by the carcass. The economic values of eating quality traits and other consumer preference traits are derived from consumers’ demand for pork products. Demand was defined as the function defining the quantity and quality of pork that consumers will buy at various prices.

Economic values are presented in Table 1. The economic values were divided by the SD for the trait to put all value in the same units of measure. The relative economic value is calculated by setting one trait as the basis by which all comparisons will be made. In this example BF10 is set as the base trait and therefore has a relative economic value of $1.00. The relative economic values indicate how much additional profit can be earned by making an improvement of one standard deviation in one trait versus another trait. Relative economic values also indicate what profit is possible by genetic selection for each trait.

These results suggest that meat quality traits may be relatively important in the production model. However, the quality values were based solely on a small consumer sample. In the meat quality situation there is not always a clear association between the direction of change required and the method of payment to the producer. Under these circumstances the economic values are difficult to derive without error. Considerable uncertainty remains about how much of a premium pork marketers can collect for differentiated pork products and what volume they can sell at that price. Uncertainty also exists about the costs that marketers will incur to distinguish their products and how much of a premium they will pass through to packers and producers. It is also known that losses occur during slaughter and processing due to poor pork quality. However, the magnitude of this loss is not known. Another loss that can occur is when a consumer dissatisfied with the pork product never purchases pork again; this too is hard to measure. Ultimately a producer must make genetic choices based on available incentives.

Breeding Objectives

The economic breeding objective is an aggregate of breeding values weighted by their respective economic values. The selection index is calculated in such a way that the correlation between the index and the breeding objective is maximized. Table 2 describes possible indexes for ranking animals on a combination of eight traits incorporating growth, carcass and muscle quality measures. Information from Table 1 and the NPPC Terminal Sire Line Evaluation was used to construct the weights presented for the various indexes. The r_IH is an estimate of the accuracy level that phenotypic measurements of the traits included in the index predict the true genetic merit of the individual. Using the accuracy value as a guide this table suggests that the index to best predict genetic merit for this set of eight traits is index 2. While accuracy is greater for 1 there is also a significantly greater cost associated with the measurement of feed:gain, drip loss and tenderness. Index 2 includes phenotypic measure of D250, BF10, LMA, pH and IMF. It can be observed that consumers indicate potential premiums on eating quality traits (intramuscular fat and others) that would drastically alter sire line selection indexes that had previously excluded eating quality traits (Index 2 vs Index 5).

Summary