Selection to reduce residual feed intake in pigs produces a correlated response in juvenile insulin-like growth factor-I concentration

Abstract

0.05) significantly from zero (0.06 ± 0.14 and -0.19 ± 0.14). Selection for decreased RFI produced a direct response in RFI, as expected, and was accompanied by downward correlated responses in ADFI, juvenile IGF-I, backfat, and growth traits, listed in order of decreas-ing relative magnitude, and an increased loin muscle area. The correlated response in IGF-I to selection on RFI demonstrates that this physiological measure is ge-netically associated with efficiency, and is thus useful as an early information source to estimate genetic merit for efficiency before performance testing. Decreased ju-venile IGF-I is associated with leaner, more efficient animals. © 2010 American Society of Animal Science.