An evaluation of biological and conventional pig selection indices

Abstract

Two biological and 4 conventional pig selection indices were compared. The biological indices were lean meat growth (LGRTH) and lean meat feed conversion (LFCR). The conventional indices included average daily gain (ADG) and back fat measured at the P2 site (FP2) as criteria (index OF), or as in OF but with the addition of feed conversion ratio (FCR) as a selection criterion (index BTS). Also, using the same criteria as in BTS and OF, restricted indices were derived setting the genetic change in FP2 at zero (indices BTS.FP2 and OF.FP2). The correlated response in average daily feed intake (ADI) was calculated for all indices. The application of all indices resulted in variable, but desirable, predicted genetic changes in ADG, FCR and FP2. The correlated response in AD1 was positive, except for BTS and LFCR, where it was zero and negative, respectively. The correlations among all indices were high (r > 0.7) except for those restricting FP2. It is concluded that conventional selection indices have advantages over biological indices because they more easily enable the monitoring of changes in the components of overall merit and updating of breeding objectives.