Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/29021
Title: Strategies and cost-benefit of selecting for a polled sheep nucleus by using DNA testing
Contributor(s): Granleese, T  (author); Clark, S A  (author)orcid ; Duijvesteijn, N  (author); Bradley, P E (author); van der Werf, J H J  (author)orcid 
Publication Date: 2019
DOI: 10.1071/AN17720
Handle Link: https://hdl.handle.net/1959.11/29021
Abstract: The present study assessed the effectiveness and cost-benefit of several genotyping strategies for breeding poll Merino sheep in a closed nucleus with different initial allele frequencies and assuming a single-gene responsible for the horn or poll phenotype. We assumed that selection was based on phenotypes or genotypes for a single gene conferring polledness via a complete-dominance model. Under such a model, a complete fixation of the 'polled allele' (P) requires genotyping of the ewe-selection candidates. Testing a higher proportion of female candidates resulted in a faster fixation of the P-allele. Fixation ranged from 1 year of selection with a high starting P-allele frequency of 0.9, to 7 years for low starting P-allele frequencies of 0.3. When premiums of AU$50 or AU$100 were paid for rams with a PP genotype, breeding for PP genotypes was not profitable when the starting P-allele frequency was below 0.7. If the starting allele frequency was above 0.7, net profitability was positive over 10 years when premiums of AU$200 were paid for known PP-genotype rams. While fixing the P-allele, genetic gain for production traits was slowed down in the first 5 years of selection by up to 23% and 3% for initial P allele-frequencies of 0.3 and 0.9 respectively. Lost genetic gain due to fixing the P-allele, which can never be recovered in a closed nucleus, incurred 200-800% higher costs than the DNA testing costs. Rates of genetic gain recovered to pre-P-allele selection level rates of genetic gain once the P-allele was fixed. Testing a maximum of 25% ewe-selection candidates was the least expensive strategy across all starting allele frequencies and premiums. To avoid large losses of genetic gain in a closed nucleus with low P-allele starting frequencies, opening the nucleus should be considered to increase starting P-allele frequencies and also to potentially increase rates of genetic gain to offset the economic loss caused by P-selection.
Publication Type: Journal Article
Source of Publication: Animal Production Science, 59(8), p. 1428-1437
Publisher: CSIRO Publishing
Place of Publication: Australia
ISSN: 1836-5787
1836-0939
Fields of Research (FoR) 2008: 070201 Animal Breeding
060412 Quantitative Genetics (incl. Disease and Trait Mapping Genetics)
070202 Animal Growth and Development
Fields of Research (FoR) 2020: 300305 Animal reproduction and breeding
310506 Gene mapping
300301 Animal growth and development
Socio-Economic Objective (SEO) 2008: 830310 Sheep - Meat
830311 Sheep - Wool
Socio-Economic Objective (SEO) 2020: 100412 Sheep for meat
100413 Sheep for wool
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article
School of Environmental and Rural Science

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