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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Genetics and Animal Breeding » Research » Publications at this Location » Publication #117334

Title: COMPARISON OF MODELS FOR ESTIMATING DIRECT AND MATERNAL GENETIC EFFECTS FOR WEANING WEIGHT OF HEREFORD CATTLE

Author
item SOPANNARATH, P.
item BERTRAND, J.
item Van Vleck, Lloyd
item TUMWASORN, S.

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/5/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Weaning weights adjusted for age of calf and dam from 4 sets of Hereford cattle from the American Hereford Association were analyzed. Number of records ranged from 29,562 to 30,383. Variance and covariance components were estimated using REML. Ten animal models were applied to estimate genetic parameters. Model 1 included fixed contemporary group (weaning herd, work group, sex, management group, feeding code) and year-season effects and random direct and maternal genetic, maternal permanent and residual environmental effects. Based on Model 1, MOdels 2-9 additionally included 2) sire x herd, 3) sire x year, 4) sire x sex, 5) sire x age of dam, 6) sire x herd-year, 7) sire x herd-year-sex, 8) sire x herd-year- sex-age of dam and 9) sire x dam interaction effects, respectively. Model 6 was significantly best (likelihood ratio test). Model 10 added sire x dam effects to Model 6 and improved the likelihood. Compared with Model 1, ,the log likelihood improved significantly. Model 1 gave highest estimates of direct and maternal h2 and negative direct-maternal correlations. With sire x dam interaction effects (Model 9), estimates were similar to Model 1. With Models 2-8, estimates of direct and maternal h2 were smaller and r(a,m) was larger than Model 1. Estimates from Models 6 and 10 were similar. With Model 10, estimates were .18 to .19 for direct h2, .14 to .16 for maternal h2, -.40 to -.31 for r(a,m). Fractions of variance due to sire x herd-year and sire dam interactions were .03 to .07 and .04 to .09, respectively. Results suggest that direct and maternal h2 are biased upward and r(a,m) biased downward if sire x herd-year interaction effects are not in model. Sire x dam interaction effects did not affect estimates of variances of other effects.