Genetic Parameters Revisited for Ultrasound Scanning Traits in Australian Sheep

Title
Genetic Parameters Revisited for Ultrasound Scanning Traits in Australian Sheep
Publication Date
2014
Author(s)
Mortimer, S I
Swan, Andrew
( author )
OrcID: https://orcid.org/0000-0001-8048-3169
Email: aswan@une.edu.au
UNE Id une-id:aswan
Brown, Daniel
( author )
OrcID: https://orcid.org/0000-0002-4786-7563
Email: dbrown2@une.edu.au
UNE Id une-id:dbrown2
Van Der Werf, Julius H
( author )
OrcID: https://orcid.org/0000-0003-2512-1696
Email: jvanderw@une.edu.au
UNE Id une-id:jvanderw
Type of document
Conference Publication
Language
en
Entity Type
Publication
Publisher
American Society of Animal Science
Place of publication
Champaign, United States of America
UNE publication id
une:17584
Abstract
This study estimated genetic parameters for ultrasound scanning measurements of fat (FAT) and eye muscle (EMD) depths in sheep, expressed during the early post weaning period, from analyses including and excluding body weight (WT) as a covariate and compared these to equivalent genetic parameters derived post analysis. Direct heritability estimates from univariate analyses for all traits were moderate (0.17 to 0.25). Estimates from models with WT adjustment were about 30% higher, while maternal environmental effects were not significant. From bivariate analyses of WT with each of EMD and FAT, genetic variance for WT where EMD and FAT were adjusted was higher than the derived estimates, resulting in increased heritability estimates for WT and negative genetic correlations in comparison to both unadjusted estimates (which were positive) and derived estimates (which were weakly positive). We conclude that the phenotypic adjustment of scanned eye muscle and fat depths to a constant body weight could overcorrect the estimated breeding values for these traits and that post analysis adjustment may be a better approach. Adjusting genetic parameter estimates post analysis would allow use of more appropriate models in genetic evaluation.
Link
Citation
Proceedings of the 10th World Congress on Genetics Applied to Livestock Production (WCGALP) (Species Breeding: Sheep and goats), p. 1-3
Start page
1
End page
3

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