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ARS Home » Research » Publications at this Location » Publication #76876
Title: EFFECT OF INBREEDING AND HETEROZYGOSITY ON PREWEANING TRAITS IN A CLOSED POPULATION OF HEREFORDS

Author
item PARIACOTE, F. - UNIV. OF NEBRASKA-LINCOLN
item Van Vleck, Lloyd
item Macneil, Michael

Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Preweaning traits from Livestock and Range Research Laboratory were used to evaluate effects of inbreeding and heterozygosity. Five one-bull founder lines were identified. Line members were all descendants of a founder Hereford bull. The base population was existing males and females when line formation started. Individuals not related to lines were considered immigrants. Heterozygosity coefficients were computed for crosses between lines. A total of 8065 records of birth weight and 7380 records of preweaning daily gain and weaning weight were analyzed by derivative-free REML using a model that included fixed effects of sex, combination of year- of birth, parity of dam with covariates for direct and maternal line fractions, and direct and maternal inbreeding and heterozygosity coefficients. Direct and maternal genetic and uncorrelated maternal permanent environmental effects were random effects. Averaged across lines, ,direct and maternal inbreeding and heterozygosity coefficients were 9.8, 34.2, 7.5 and 29.4%, respectively. Direct and maternal inbreeding covariates were statistically significant. Birth weight was reduced by 5.8 plus/minus 1.1 and 4.7 plus/minus 1.3, preweaning daily gain by .19 plus/ minus .03 and .25 plus/minus .04 and weaning weight by 44.5 plus/minus 6.6 and 56.1 plus/minus 8.4 kg per 100% of direct and maternal inbreeding. Estimates for direct and maternal heritability, and direct-maternal genetic correlations were .37, .12, -.01; .16, .25, -.27 and .17, .26, -.21 for birth weight, daily gain and weaning weight. Results support the argument that heterosis represents recovery of accumulated inbreeding depression. Results indicate selection can overcome inbreeding depression and that an- tagonism exists between direct and maternal genetic effects for weaning wt.