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Title: PARAMETER ESTIMATES OBTAINED USING GIBBS SAMPLING FOR GROWTH TRAITS AND MUSCLE SCORE IN HEREFORD CATTLE SELECTED FOR WEANING WEIGHT, YEARLING WEIGHT, OR AN INDEX OF YEARLING WEIGHT AND MUSCLE SCORE

Author
item Van Tassell, Curtis - Curt
item Van Vleck, Lloyd
item KOCH, ROBERT - UNIV. OF NEBRASKA-LINCOLN

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Birth weight (BW), weaning gain (WG), post-weaning gain (PWG) and muscle score (MS) observations for animals selected for increased weaning weight (n = 2811), yearling weight (n = 2706), index of yearling weight and muscle score (n = 2752), and control (n = 1699) were analyzed with a multiple trait animal model including fixed sex-year effects, random direct and maternal genetic, maternal permanent environmental, and residual effects. A total of 10,575 animals were included in the pedigee. Numbers of observations ranged from 7,946 to 9,968 for the 4 traits. Gibbs sampling estimates were calculated using the multiple trait Gibbs sampler for animal models (MTGSAM) programs. REML estimation of (co)variance components was not possible with the MTDFREML programs because the simplex search algorithm is extremely slow to converge due to the large number of parameters estimated (56 variance components). REML estimation using a canonical transformation was not possible due to missing observations. A total of 200,000 rounds of sampling were used, with the first 100,000 rounds discarded as burn-in. Direct heritability estimates were .46, .19, .67, and .70 for BW, WG, PWG, and MS, respectively. Maternal heritability estimates were .12, .20, .11, and .14. Estimates of phenotypic variance were 15.8 kg2, 466 kg2, 628 kg2, and 5.8. Direct (maternal) genetic correlation estimates for BW with WG, PWG, and MS were .25, .36, and .18 (.26, .12, and .13), for WG with PWG and MS were .50 and .05 (-.02 and .23), and for PWG with MS was -.33 (-.62). Estimates of correlations of direct and maternal genetic effects were .03, -.24, -.62, and -.68 for BW, WG, PWG, and MS. Additional rounds of Gibbs sampling will be calculated to test whether estimates have converged with 100,000 post burn-in samples.