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United States Department of Agriculture

Agricultural Research Service

Title: Comparison of Models for Traits of Rambouillet Sheep

Authors
item Van Vleck, Lloyd
item Hanford, Kathryn
item Snowder, Gary

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2000
Publication Date: March 1, 2000
Citation: Van Vleck, L.D., Hanford, K.J., Snowder, G.D. 2000. Comparison of models for traits of rambouillet sheep [abstract]. Journal of Animal Science 80(Suppl. 1)43.

Interpretive Summary: No interpretive summary is required.

Technical Abstract: Several analytical models for birth weight (BWT, 17, n = 35,604), weaning weight (WWT, 11, n = 34,114), fleece weight (FWT, 8, n = 38,113) and number born (NB, 8, n = 39,029) were compared for Rambouillet sheep born at the USSES (1950-1998). For BWT, direct and maternal heritability were 0.26 and 0.19 (correlation of about zero) for all models. Models that also included dam by year, dam by number born, and sire by dam effects were significantl better than the basic maternal effects model, accounting for 0.06, 0.04, and 0.03 of phenotypic variance. Effects of cytoplasmic line and sire by cytoplasmic line were not significant. For WWT, direct and maternal heritability were 0.18 and 0.10 with correlation of 0.31. Of the other effects, only maternal permanent environmental effects (0.05 of variance) was not zero. For FWT, heritability was 0.55 for all models, but estimates of relative variance due to dam by year (0.02), sire by dam (0.05), and sire by cytoplasmic line (0.02) were jointly significant. For NB, for all models only direct heritability (0.08) and relative permanent environmental variance (0.04) were not zero. Trait showed evidence of cytoplasmic effects. Seldom considered effects in the model did not change estimates of variance due to direct and maternal genetic effects for any trait. Variance due to dominance effects inferred from the sire by dam component of variance may be important for BWT and FWT. The basic direct-maternal effects model seems sufficient for genetic evaluations for WWT and FWT but models for BWT and NB may need to include other effects.

Last Modified: 11/23/2014
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