Alternate methods for estimating breeding values for faecal egg count data from merino studs across Australia

Title
Alternate methods for estimating breeding values for faecal egg count data from merino studs across Australia
Publication Date
2003
Author(s)
Brown, Daniel
Tier, Bruce
Editor
Editor(s): Abigail Henderson
Type of document
Conference Publication
Language
en
Entity Type
Publication
Publisher
Association for the Advancement of Animal Breeding and Genetics (AAABG)
Place of publication
Armidale, Australia
UNE publication id
une:4492
Abstract
Selection for resistance to internal parasites is of interest to many sheep breeders. However, the genetic evaluation of faecal egg count is problematic due to the variable levels of expression, as a result of interactions with the environment, the species of parasite, and its skewed distribution. Transformation, variance standardisation and adjustment for heterogeneous variances are used to overcome these problems. This study aims to identify which combination of techniques produces the most accurate estimated breeding values (EBVs). The EBVs from analysis of cube root transformed faecal egg count with (EBV_S) and without (EBV_3) variance standardisation are highly correlated (0.96). Furthermore the genetic correlation between these traits was also very high (0.95) indicating that genetically these traits are the same. EBVs estimated after homogenising the residual variances across groups produced EBVs less influenced by the level of variance in the raw data. Analysing faecal egg counts without variance standardisation did not significantly reduce the accuracy of the genetic evaluation. However, the EBVs need to be expressed on a scale that breeders can interpret.
Link
Citation
Proceedings of the Association for the Advancement of Animal Breeding and Genetics, v.15, p. 115-118
ISSN
1328-3227
ISBN
0958629927
Start page
115
End page
118

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