|Van vleck, Lloyd|
Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/24/2002
Publication Date: 12/1/2002
Citation: Splan, R.K., Cundiff, L.V., Dikeman, M.E., Van Vleck, L.D. 2002. Estimates of parameters between direct and maternal genetic effects for weaning weight and genetic effects for carcass traits in crossbred cattle. Journal of Animal Science. 80:3107-3111. Interpretive Summary: To respond to consumer demand for quality end products, seedstock and commercial beef breeders need to consider not only the traditional traits of growth, maternal ability and production efficiency in their selection decisions, but also carcass characteristics. A genetic analysis of weaning weights of 23,681 crossbred calves and carcass traits of 4,094 steers from projects at USMARC was done to establish the genetic correlations between carcass traits and direct and maternal genetic values for weaning weights. The results suggest the following. Selection for carcass traits, including tenderness, would be expected to result in improvement because of the moderate to high heritability of the traits. Selection for either increased maternal or direct weaning weight would be expected to result in increased carcass weight, ribeye area, and fat thickness. Selection for maternal weaning weight would also be expected to result in increased carcass fat percentage and marbling and decreased retail product percentage. Selection for only direct weaning weight would also be expected to slightly decrease marbling and retail product percentage. Selection for either increased maternal or direct weaning weight would not be expected to affect tenderness. Many of these changes are not likely to be large.
Technical Abstract: Estimates of heritabilities and genetic correlations were obtained from weaning weight records of 23,681 crossbred beef cattle of both sexes and carcass performance data of 4,094 crossbred steers recorded at USMARC. Carcass traits were hot carcass weight, ribeye area, adjusted fat thickness, marbling score, Warner-Bratzler shear force, and retail product, fat, bone, and kidney and pelvic and heart fat percentages. Weaning weight was modeled with fixed effects of age of dam, sex, line (breed combination) and birth year, with calendar birth day as a covariate and random effects of direct and maternal genetic and maternal permanent environment. Models for carcass traits included fixed effects of age of dam, line and birth year, with covariates for weaning and slaughter age and random effects of animal genetic and total maternal (dam). Direct and maternal heritabilities for weaning weight were 0.14 plus/minus 0.02 and 0.19 plus/minus 0.02, respectively. Estimate of direct-maternal genetic correlation for weaning weight was negative (-0.18 plus/minus 0.08). Heritabilities for carcass traits were 0.34 to 0.60. Estimates of genetic correlations between direct genetic effects for wean- ing weight and carcass traits were small except with hot carcass weight (0.70), ribeye area (0.29) and adjusted fat thickness (0.26). Estimates of genetic correlations between maternal genetic effects for weaning weight and direct genetic effects for carcass traits were near zero except with hot carcass weight (0.61), retail product percentage (-0.33), fat percent- age (0.33), ribeye area (0.29), marbling score (0.28) and adjusted fat thickness (0.25) which indicate the genotype for maternal weaning weight may be correlated with genotypes for carcass performance.