Hostname: page-component-586b7cd67f-2plfb Total loading time: 0 Render date: 2024-11-23T01:34:15.417Z Has data issue: false hasContentIssue false
  • English
  • Français

Selection and response within the nucleus of a sheep group-breeding scheme

Published online by Cambridge University Press:  02 September 2010

S. Anderson  and
M. K. Curran
S. Anderson
Affiliation:
Wye College, Ashford, Kent TN25 5AH
M. K. Curran
Affiliation:
Wye College, Ashford, Kent TN25 5AH
Get access

Abstract

An evaluation of the response to selection for prolificacy within a nucleus sheep flock of a commercial group-breeding scheme is presented. In 1979, the Romney Group Breeders formed a nucleus flock of 120 prolific ewes chosen from 12 contributing flocks. A control flock was established in 1982 from the same source. The analysis was conducted on the trait of litter size. Selection differentials are presented for each year of birth progeny group in both flocks. Expected selection response was calculated from selection differentials and was found to have an average value of 1·5% of parent mean litter size per year. Using least squares procedures the litter size performance of control and nucleus ewes of 2, 3 and 4 years of age was corrected for environmental effects. Realized response was estimated from the differences between corrected litter size means of control and nucleus flocks. Response in litter size was found to be significant within years and within ewe age groups (P < 0·05).

Keywords

breeding programmeslitter sizeselectionssheep
Type
Research Article
Information
Animal Production , Volume 51 , Issue 3 , December 1990 , pp. 593 - 599
Copyright
Copyright © British Society of Animal Science 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Anderson, S. 1987. Response to selection for prolificacy in sheep within a group breeding scheme nucleus flock. Ph.D. Thesis, University of London.Google Scholar
Atkins, K. D. 1980. Selection for skin folds and fertility. Proceedings of the Australian Society of Animal Production 13: 174–176.Google Scholar
Atkins, D. D., McGuirk, B. J. and Thompson, R. 1986. Intra-flock genetic improvement programmes in sheep and goats. Proceedings of the 3rd World Congress on Genetics Applied to Livestock Production, Vol. 9, pp. 605–617.Google Scholar
Bradford, G. E. 1985. Selection for litter size. In Genetics of Reproduction in Sheep (ed. Land, R. B. and Robinson, D. W.), pp. 3–18. Butterworths, London.CrossRefGoogle Scholar
Bradford, G. E., Torrell, D. T., Lasslo, L. and Neira, R. 1981. Selection for growth and reproduction in Targhee sheep. In Sheep and Wool Days, Special Report 613, pp. 43–55. Oregan State University, Corvallis.Google Scholar
Clarke, J. N. 1972. Current levels of performance in the Ruakura fertility flock of Romney sheep. Proceedings of the New Zealand Society of Animal Production 32: 99–111.Google Scholar
Dalton, D. C. and Baker, R. L. 1980. Selection experiments with beef cattle and sheep. In Selection Experiments in Laboratory and Domestic Animals (ed. Robertson, A.), pp. 131–143. Commonwealth Agricultural Bureaux, Slough.Google Scholar
Falconer, D. S. 1981. Introduction to Quantitative Genetics. 2nd ed. Longmans, London.Google Scholar
Hanrahan, J. P. 1976. Response to selection for litter size in Galway sheep. Irish Journal of Agricultural Research 15: 291–300.Google Scholar
Hanrahan, J. P. 1982. Selection for increased ovulation rate, litter size and embryo survival. Proceedings of 2nd World Congress of Genetics (ed. Haresign, W.), pp. 294–309. Butterworths, London.Google Scholar
Hanrahan, J. P. 1984. Results of selection for increased litter size and ovulation rate in sheep. Proceedings of the 2nd World Congress on Sheep and Beef Cattle Breeding, Pretoria, Republic of South Africa, pp. 483–493.Google Scholar
Hill, W. G. 1972. Estimation of genetic change. I. General theory and design of control populations. Animal Breeding Abstracts 40: 1–15.Google Scholar
James, J. W. 1986. Cumulative selection differentials and realized heritabilities with overlapping generations. Animal Production 42: 411–415.Google Scholar
Land, R. B., Atkins, K. D. and Roberts, R. C. 1983. Genetic improvement of reproductive performance. In Sheep Production (ed. Haresign, W.), pp. 515–535. Butterworths, London.Google Scholar
Mann, T. L. J., Taplin, D. E. and Brady, R. E. 1978. Response to partial selection for fecundity in Merino sheep. Australian Journal of Experimental Agriculture and Animal Husbandry 18: 635–642.CrossRefGoogle Scholar
Meyer, H. N. and Clarke, J. N. 1982. Effect of ewe ovulation rate and uterine efficiency on breed and strain variation in litter size. Proceedings of the New Zealand Society of Animal Production 42: 33–35.Google Scholar
Mueller, J. P. and James, J. W. 1984. Developments in open nucleus breeding systems. Proceedings of the 2nd world Congress on nucleus breeding systems. Sheep and Beef Cattle Breeding, Pretoria, Republic of South Africa, pp. 1–8.Google Scholar
Owen, J. B. 1986. Group breeding schemes and simplified recording in sheep improvement. In New Techniques in Sheep Production (ed. Marai, I. F. M. and Owen, J. B.), pp. 157–162. Butterworths, London.Google Scholar
Smith, C. 1984. Rates of genetic change in farm livestock. Research and Development in Agriculture 4: 79–85.Google Scholar
Snedecor, G. W. and Cochran, G. 1980. Statistical Methods. 7th ed. Iowa State University Press, Ames, la.Google Scholar
Turner, H. N. 1978. Selection for reproduction rate in Australian Merino sheep: direct responses. Australian Journal of Agricultural Research 29: 327–350.CrossRefGoogle Scholar
Turner, R. W. and Parker, A. G. M. 1984. New Zealand Group Breeding Schemes. Proceedings of the 2nd World Congress on Sheep and Beef Cattle Breeding, Pretoria, Republic of South Africa, pp. 214–221.Google Scholar