Evaluation of Commonly Used Lean Prediction Equations

Purdue University 1999 Swine Research Report. A great deal of work has been done on developing equations for estimating fat-free lean mass in pigs (Fahey et al., 1977; Forrest et al., 1989; Orcutt et al., 1990). Most equations are evaluated by statistics such as coefficient of determination (R2) and residual standard deviation (RSD) for the data set from which they were derived. A better means of evaluating prediction equations is to use the prediction equations on other data sets. This is called an out of sample evaluation. Most equations currently in use have not been evaluated for the extent to which they account for genotype and sex differences in carcass composition. Packers produce pork products from pigs of diverse genotype backgrounds and different sexes. Therefore, any realistic attempt to develop an unbiased evaluation system should account for a high percentage of genotype and sex differences. Also, prediction equations should accurately predict the lean content of carcasses in different weight ranges. The objective of this study was to examine the impact of biases associated with genotype, sex and weight range on prediction of fat-free lean mass in pigs.