|Van Vleck, Lloyd|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2004
Publication Date: 9/1/2005
Citation: Cassady, J.P., Van Vleck, L.D. 2005. Estimation of (co)variance components due to genetic competition effects in pigs [abstract]. Journal of Animal Science. 83 (Supplement 2):6-7. (Abstract #22) Interpretive Summary: No interpretive summary is required.
Technical Abstract: The objective of this project was to estimate (co) variance components for direct and competition genetic effects in pigs. Public pressure is increasing on American pig producers to consider animal well-being. Significant efforts have been placed on modifying facilities and production practices to create a better environment for pigs. However, relatively little consideration has been given to adapting pigs themselves. If heritable measures of pig behavior can be identified, pig behavior might be modified genetically to benefit both pigs and producers. Pigs (n = 410) in this experiment were a cross between a Duroc-Hampshire composite line selected for decreased days to 105 kg (DAYS) and backfat and a Landrace-Large White line selected for increased litter size. At 76 +/- 6 d of age, pigs were penned in groups of eight by sex. Area of each pen was 7.4 square meters. A restriction was that full-sibs were not penned together. Traits recorded were on test weight (IWT), ADG, DAYS, and backfat adjusted to 105 kg (ABF). Analyses were with a version of the MTDFREML program, which was modified to allow for a vector of second animal genetic effects. Pen mates were considered to be competitors and were entered as second animal effects. Thus, each pig had effects of seven competitors included in its record. Estimates of heritabilities of direct effects were 0.57, 0.63 and 0.28 for DAYS, ADG, and ABF, respectively. Estimates of heritabilities of competition effects were 0.01, 0.02, and 0.00 for DAYS, ADG, and ABF, respectively. Although heritability of competition effects appears to be very low in this experiment, estimation of these (co) variance components in larger experiments with pigs of different genetic backgrounds and under different pen environments may be of interest. How competition effects should be included in selection indices is important to consider as would rankings of potential breeding animals with and without considering genetic competition effects.