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United States Department of Agriculture

Agricultural Research Service

Research Project: EVALUATION, DEVELOPMENT, AND USE OF GENETIC RESOURCES TO IMPROVE LIFE-CYCLE EFFICIENCY OF BEEF CATTLE AND SHEEP

Location: Genetics, Breeding, & Animal Health

Title: Factors associated with feed intake of Angus steers

Authors
item Dib, Marco - UNIV OF NEBRASKA-LINCOLN
item Taylor, Jerry - UNIV OF MISSOURI-COLUMBIA
item Schnabel, Robert - UNIV OF MISSOURI-COLUMBIA
item Van Vleck, Lloyd - ARS COLLABORATOR

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: November 13, 2008
Publication Date: N/A

Technical Abstract: Estimates of variance components were obtained from 475 records of average (AFI) and residual feed intake (RFI). Covariates in various (8) models included average daily gain (G), age (A) and weight (W) on test, and slaughter (S) and ultrasound (U) carcass measures (fat thickness, ribeye area and marbling score or intramuscular fat). All models included contemporary group (days on feed x pen x year). For AFI, choice of model affected estimates of genetic and residual variances and heritability. Heritability was largest (0.55) for model with A, W, and G. Other models resulted in similar heritability estimates (0.31-0.37) although components of variance varied (genetic: 0.10-0.23; residual: 0.20-0.50). Models including either S or U in addition to A and W resulted in similar estimates of parameters. For RFI (AFI adjusted for ADG and metabolic body weight), models with only A and W as covariates and with no covariates resulted in near null estimates of parameters. The largest estimate of heritability was with A, W, and G as covariates (0.61). Estimates of heritability were greater with covariates for slaughter as compared with ultrasound carcass measures (0.41 and 0.42 vs. 0.34 and 0.35). With the exception of the two sets of near null estimates for RFI, estimates of phenotypic variances were similar for AFI and RFI. Although heritability estimates (and accuracy of EBV) for AFI are similar with or without adjustment to constant carcass measures, standard errors of prediction with adjustment for carcass measures would be smaller because of smaller genetic variance.

Last Modified: 7/30/2014
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