Animal Industry Report

Extension Number

ASL R3266



Summary and Implications

Selection for decreased RFI is controversial from a welfare standpoint, given that the genetic variation in RFI reflects the genetic variation in activity and response to stress. The objective of this experiment was to examine the behavioral metric correlations and growth performance of barrows divergently selected for residual feed intake (RFI) during a novel object test. Forty low-(LRFI, more feed efficient) and 40 high-RFI (HRFI, less feed efficient) barrows from the 8th generation Yorkshire selection lines were randomly selected. Barrows were evaluated in a Novel Object Test for zone crossing, zone 1 (defined as the mouth, nose, and/or face of the pig contact any part of zone 1), escape, freeze, urination and defecation frequencies and their effect on performance measures. Within the HRFI line, zone crossing frequency accounted for 10.9% of the variation in 10th-rib back fat at off test (r= 0.33; P = 0.04). Within the LRFI line, freeze frequency accounted for 13.7% of the variation in feed conversion ratio (r= 0.37; P = 0.03) and defecation frequency accounted for 11.6% of the variation in 10th-rib back fat at off test (r= 0.34; P = 0.05). Therefore, within the context of the ISU swine genetic selection program for improved lean accretion and feed efficiency, there were no negative behavioral metrics that determinately affected performance measures during the grow-finish period.

Copyright Holder

Iowa State University