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A simulation study of open nucleus and closed nucleus breeding systems in a sheep population

Published online by Cambridge University Press:  02 September 2010

J. A. Roden
J. A. Roden
Affiliation:
Department of Agriculture, University of Aberdeen, 581 King Street, Aberdeen AB9 1UD
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Abstract

Stochastic simulation was used to compare the results of alternative breeding systems in a sheep population divided into 10 flocks of 120 ewes. The breeding systems compared were selection within closed flocks (CF), a closed nucleus system (CNS), an open nucleus system (ONS) and open nucleus systems with the selection of nucleus replacements being restricted to either nucleus born males (ONSRm) or nucleus born females (ONSRf). Selection was for a best linear unbiased prediction of breeding value for lamb live weight which had a heritability of 0·17. The open nucleus breeding systems (ONS, ONSRm, ONSRf) resulted in higher rates of genetic gain, more predictable selection responses and lower rates of inbreeding than either the closed nucleus system (CNS) or selection within closed flocks (CF). Initial genetic differences between flocks resulted in higher rates of genetic gain in the nucleus breeding systems due to the use of between flock genetic variance. In the ONS system up to 25% of nucleus sires and approximately 50% of nucleus dams were born in base flocks. Nevertheless if selection of either nucleus sires or dams was restricted to nucleus born animals there was very little change in genetic gain or rate of inbreeding.

Keywords

breeding programmessheepsimulation models
Type
Research Article
Information
Animal Science , Volume 60 , Issue 1 , February 1995 , pp. 117 - 124
Copyright
Copyright © British Society of Animal Science 1995

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References

Dekkers, J. C. M. 1992. Asymptotic response to selection on best linear unbiased predictors of breeding values. Animal Production 54: 351–360.Google Scholar
del-Bosque Gonzalez, A. S. 1989. Simulations of nucleus breeding schemes for wool production. PhD. thesis, University of New England, Armidale.Google Scholar
Hopkins, I. R. and James, J. W. 1977. Some optimum selection strategies and age structures with overlapping generations. Animal Production 25: 111–132.Google Scholar
Hopkins, I. R. and James, J. W. 1978. Theory of nucleus breeding schemes with overlapping generations. Theoretical and Applied Genetics 53: 17–24.CrossRefGoogle ScholarPubMed
Jackson, N. and Turner, H. N. 1972. Optimal structure for a co-operative nucleus breeding system. Proceedings of Australian Society of Animal Production 9: 55–64.Google Scholar
James, J. W. 1977. Open nucleus breeding systems. Animal Production 24: 287–305.Google Scholar
James, J. W. 1978. Effective population size in open nucleus breeding schemes. Acta Agriculturae Scandinavica 28: 387–392.CrossRefGoogle Scholar
Meat and Livestock Commission. 1988. Sheep in Britain. Meat and Livestock Commission, Milton Keynes.Google Scholar
Meuwissen, T. H. E. 1991. Expectation and variance of genetic gain in open and closed nucleus and progeny testing schemes. Animal Production 53: 133–141.Google Scholar
Meuwissen, T. H. E. and Woolliams, J. A. 1993. Responses of multi-trait selection in open nucleus schemes for dairy cattle breeding. Animal Production 56: 293–299.Google Scholar
Mueller, J. P. and James, J. W. 1983. Effects of reduced variance due to selection in open-nucleus breeding systems. Australian journal of Agricultural Research 34: 53–62.CrossRefGoogle Scholar
Nicholas, F. W. 1980. Size of population required for artificial selection. Genetical Research 35: 85–95.CrossRefGoogle ScholarPubMed
Owen, J. B. and Williams, G. LI. 1980. The evaluation of group breeding schemes in relation to the structure of the breeding system. Proceedings of the thirty-first annual meeting of the European Association for Animal Production.CrossRefGoogle Scholar
Roden, J. A. 1994. Review of the theory of open nucleus breeding systems. Animal Breeding Abstracts 62: 151–157.Google Scholar
Shepherd, R. K. 1991. Multi-tier open nucleus breeding systems. Ph.D. thesis, University of New England, Armidale.Google Scholar
Shepherd, R. K. and Kinghorn, B. P. 1992. Optimising multi-tier open nucleus breeding schemes. Theoretical and Applied Genetics 85: 372–378.CrossRefGoogle ScholarPubMed
Westell, R. A., Quass, R. L. and Van Vleck, L. D. 1988. Genetic groups in an animal model. Journal of Dairy Science 71: 1310–1318.CrossRefGoogle Scholar
Woolliams, J. A. and Meuwissen, T. H. E. 1993. Decision rules and variance of response in breeding schemes. Animal Production 56: 179–186.Google Scholar
Wray, N. R. and Hill, W. G. 1989. Asymptotic rates of response from index selection. Animal Production 49: 217–227.Google Scholar