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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 #107727
Title: MODELS FOR ESTIMATING THE GENETIC CORRELATION BETWEEN DIRECT AND MATERNAL EFFECTS

Author
item VAN VLECK, LLOYD
item MACNEIL, MICHAEL

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: A large negative genetic correlation between direct and maternal effects (r-am) is often reported for weaning weight of beef cattle. Weaning weights of 3854 calves of the Ft. Keogh Line 1 Herefords were analyzed to determine consequences of adding to usual direct-maternal genetic model (AM), effects due to sire by year interaction (S), grandmaternal genetic effects (G), and dregressions (R) on calendar birth day of dam and birth, weaning and yearling weights of dam. Fixed factors in all models were year-sex and age of dam with linear covariates for calendar birth day of calf with the weaning weight and inbreeding coefficients of calf and dam. Permanent environmental effects of dam and grandam as appropriate were in models with M and G. Birth day of dam was significant but did not affect estimates of genetic parameters. Birth and yearling weights of dam were not significant. Weaning weight of dam was significant and did affect estimates of genetic parameters, primarily increasing r-am from -.39 to -.04 for AM and from -.16 to .03 for AMG. The AMG model increased maternal heritability from .16 to .41 and r-am from -.37 to -.16. Effect of G(R) depended on whether R(G) was also in model. Addition of sire by year interaction slightly reduced direct heritability and slightly increased r-am by .08 for AM and .05 for AMG. Effect of S on r-am was similar for all models. Likelihoods for models with S and G were significantly better than for models without S and G. The AMG models introduced a large negative genetic correlation between maternal and grandmaternal effects (-.82 to -.89). Effects of R were larger than effects of G and S on r-am although G increased the likelihood the most. These results indicate that modeling maternal genetic effects for genetic evaluation is a complex and unsolved problem.