Different approaches of estimating economical values for drip loss as lognormally distributed trait

Economic values for meat quality traits for breeding purposes are often calculated assuming normal distribution of the trait. Phenotypic data on drip loss measurements regarding case-ready meat (CRM) and premium cuts (PC) from a field trial of 374 commercially slaughtered pigs revealed lognormal distribution rather than normal distribution for this population. Three different approaches of calculating the economic values (assuming normal distribution, lognormal distribution and shifted lognormal distribution) were compared considering in a first scenario four quality classes and in a second scenario linear weight loss. Differences among the approaches of calculation of economic values were found in magnitude and position of the maximum absolute economic value. The highest absolute economic values for case-ready meat drip loss of the ham regarding four quality classes were obtained at population means of 4.20, 4.48 and 4.80% with -0.67, -0.80 and -0.85 EUR per unit drip loss using approaches assuming normal distribution, lognormal distribution and shifted lognormal distribution, respectively. Economic values calculated under the assumption of linear weight loss resulted in a large range of similar economic values for all three methods. Besides the type of distribution, the relation between standard deviation and width of the meat quality classes and the position of the meat quality classes were found to be main factors influencing the economic value functions. For the present data, the better fit of lognormal distribution to the data and the differences in highest absolute economic values favoured the approach accounting for appropriate distribution in particular when only few meat quality classes are used. (C) 2007 Elsevier B.V. All rights reserved.