|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2008
Publication Date: 7/1/2008
Citation: Chen, C., Johnson, R.K., Kachman, S.D., Van Vleck, L.D. 2008. Estimates of genetic correlations among growth traits including competition effects [abstract]. Journal of Animal Science Supplement. 86 (E-Supplement 2):510. (Abstract #533). Interpretive Summary:
Technical Abstract: The objective was to estimate genetic parameters of direct and competition effects for traits measured at the end of a growth test utilizing multi-trait analyses. A total of 9,720 boars were tested with 15 boars per pen from about 71 to 161 d of age and weight from 31 to 120 kg. Traits analyzed with initial age on test as a covariate were average daily gain during test (ADG), days to 110 kg (D110), and daily feed intake (DFI). Backfat measured at the p2 point (BF) and muscle depth (MD) were analyzed with age off test as a covariate. Fixed effects of line and contemporary group, with random direct genetic, competition genetic, and competition environmental effects were also in the statistical model. For single-trait analyses, estimates of direct heritability were 0.30, 0.26, 0.20, 0.46, and 0.33 for ADG, D110, DFI, BF, and MD, respectively. Estimates of heritability for competition effects were near to zero for all traits. Estimates of genetic correlation between direct and competition effects were 0.06, -0.13, -0.32, 0.22, and 0.36 for ADG, D110, DFI, BF, and MD, respectively, but these are based on very small estimates of variance of competition effects. For two-trait analyses, estimates of direct genetic correlations were -0.96, 0.15, 0.44, -0.14, -0.42, 0.38, 0.16, and 0.04 for ADG-D110, ADG-BF, ADG-MD, D110-BF, D110-MD, DFI-BF, DFI-MD, and BF-MD, respectively. Estimates of direct genetic correlations for ADG-DFI and D110-DFI, however, could not be obtained because global convergence failed to be met. Estimates of competition genetic correlations among the five traits might have little meaning because estimates of variances of competition effects were close to zero for all five traits. Difficulty of analyses including competition effects with two-trait models was apparent when the average information matrix failed to provide reasonable information. Interpretation of antagonisms among traits associated with competition effects was limited in this study.