Litter size at lambing influences genetic evaluation of maternal rearing ability

Title
Litter size at lambing influences genetic evaluation of maternal rearing ability
Publication Date
2018
Author(s)
Bunter, Kim L
( author )
OrcID: https://orcid.org/0000-0001-5587-4416
Email: kbunter2@une.edu.au
UNE Id une-id:kbunter2
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
Brien, Forbes D
Smith, Jennifer
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/an16422
UNE publication id
une:23189
Abstract
The genetic parameters for maternal rearing-ability of ewes were investigated by ignoring or defining the rearing ability trait separately by litter-size class (singles versus multiples) using multi-generational data from three, fully pedigreed Merino flocks differing in prolificacy, production level and environment. Genetic correlations (ra) between litter size (LSIZE) and the percentage of lambs surviving (PLSURV) were more negative with an increasing mean flock litter size (ra: -0.21 ± 0.17 to -0.73 ± 0.08), while the corresponding range in phenotypic correlations (rp) was substantially lower (rp: –0.15 ± 0.01 to -0.33 ± 0.01). Rearing-ability traits defined separately by litter-size class were highly correlated (ra: 0.49 ± 0.19 to 0.64 ± 0.38), but not genetically identical traits in the most prolific flock. Defining rearing-ability traits separately by litter-size class reduced the antagonistic genetic correlations between LSIZE and PLSURV to between -0.39±0.14 and 0.14 ± 0.28, through accommodating the change in mean and variance of PLSURV with LSIZE. Similarly, linear transformation (TSURV) of PLSURV within each litter size to a common mean and variance reduced the antagonistic trend in genetic correlations between LSIZE and TSURV to range between -0.05±0.17 and -0.43 ±0.13. Since genetic correlations are low to moderate between TSURV and LSIZE, it is possible to select for improvements in both the number of lambs born and lamb survival simultaneously. Defining rearing-ability traits separately by litter-size class and the role of transformation will be investigated further for improving the accuracy of genetic evaluation for rearing ability across a range of flocks, breeds and environmental conditions using more extensive industry data.
Link
Citation
Animal Production Science, 58(5), p. 791-800
ISSN
1836-5787
1836-0939
Start page
791
End page
800

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