Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/30494
Title: New genomically enhanced reproduction breeding values for Merino sheep allow targeted selection for conception rate, litter size and ewe rearing ability
Contributor(s): Bunter, K L  (author)orcid ; Swan, A A  (author)orcid ; Gurman, P M  (author)orcid ; Brown, D J  (author)orcid 
Publication Date: 2021
Early Online Version: 2020-11-30
DOI: 10.1071/AN20444
Handle Link: https://hdl.handle.net/1959.11/30494
Abstract: Context: Net reproduction rate defined as number of lambs weaned for joined ewes reflects conception, litter size and the ability of ewes to rear lambs to weaning age. These three attributes can be treated as separate traits for genetic evaluation, allowing breeders to focus selection for each appropriately.
Aims: The aim of the present paper was to present characteristics of the data, models and genetic parameters estimated from Merino data, along with results demonstrating the predictive capacity of breeding values, for conception, litter size, rearing ability, maternal behaviour and body condition score.
Methods: Industry data from MERINOSELECT were used to derive phenotypes for conception, litter size and rearing ability traits separately for yearling and adult ewes, along with maternal behaviour and body condition score. Indirect traits provided correlated information, including scrotal circumference, weight, scanned fat and eye muscle depths at up to three ages (post-weaning, yearling and hogget), along with pre-joining weight and condition score for ewes. Co-variances were estimated among the 19 traits included in the analysis. Breeding values were estimated using single step genomic methodology using consensus estimates of genetic parameters, with the predictive capacity of breeding values being estimated using forward-validation.
Key results: Heritabilities ranged from 0.04 to 0.06 for conception, litter size and rearing ability, and were moderate for maternal behaviour (0.13) and condition score (0.20). Component traits were genetically controlled by some common genes, but with genetic correlations less than 0.5, each component can be selected for independently. Weight, fat depth and muscle depth measures were moderately to highly correlated with body condition score. These body development traits generally had low, favourable genetic correlations with ewe reproductive traits.
Conclusions: These procedures provide better use of data recorded by breeders subject to both data limitations and opportunities, and provide separate breeding values for conception, litter size, rearing ability, maternal behaviour and body condition score.
Implications: New breeding values with good predictive ability are now available for the component traits of reproduction. Direct recording data of the traits is required to achieve accuracy of breeding values. Australian Merino breeders are now able to select directly for components of reproduction and specific maternal characteristics.
Publication Type: Journal Article
Source of Publication: Animal Production Science, 61(3), p. 333-336
Publisher: CSIRO Publishing
Place of Publication: Australia
ISSN: 1836-5787
1836-0939
Fields of Research (FoR) 2008: 070201 Animal Breeding
Fields of Research (FoR) 2020: 300305 Animal reproduction and breeding
Socio-Economic Objective (SEO) 2008: 830311 Sheep - Wool
Socio-Economic Objective (SEO) 2020: 100413 Sheep for wool
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Animal Genetics and Breeding Unit (AGBU)
Journal Article

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