Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-08T04:47:06.771Z Has data issue: false hasContentIssue false
  • English
  • Français

Expected consequences of the segregation of a major gene in a sheep population in relation to observations on the ovulation rate of a flock of Cambridge sheep

Published online by Cambridge University Press:  02 September 2010

J. B. Owen ,
C. J. Whitaker ,
R. F. E. Axford  and
I. Ap Dewi
J. B. Owen
Affiliation:
School of Agricultural and Forest Sciences, University of Wales, Bangor LL57 2UW
C. J. Whitaker
Affiliation:
Centre for Applied Statistics, University of Wales, Bangor LL57 2UW
R. F. E. Axford
Affiliation:
School of Agricultural and Forest Sciences, University of Wales, Bangor LL57 2UW
I. Ap Dewi
Affiliation:
School of Agricultural and Forest Sciences, University of Wales, Bangor LL57 2UW
Get access

Abstract

A simple model was derived relating the phenotypic effect (g) of a major gene to observed values of the population mean and variance for a trait, at specified values of the major gene frequency and at specified basal values of the population mean and variance (in the absence of the major gene). This model was applied to a total of 549 observed values of ovulation rate in ewes of the Cambridge breed at Bangor under a range of assumptions. The mean values of ovulation rate were 2·44 for 243 ewes of 1 year of age and 37·54 for 306 ewes of 2 and 3 years of age with a coefficient of variation for both age sets of 0·50.

The results indicate a minimum value for g, in this data set, of 1·07 for 1 year old and 1·72 for 2 and 3 year old ewes. The results are also consistent with a frequency value in the region of 0·3 to 0·4, with the absence of dominance and with a reasonable concordance with Hardy-Weinburg equilibrium. The results also indicate that the value of g varies according to the background phenotype since it is lower for younger as compared with older ewes.

Keywords

major genesovulation ratesheep
Type
Research Article
Information
Animal Production , Volume 51 , Issue 2 , October 1990 , pp. 277 - 282
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

Bodin, L. and Elsen, J. M. 1989. Variability of litter size of French sheep breeds following natural or induced ovulation. Animal Production 48: 535–541.CrossRefGoogle Scholar
Bradford, G. E., Quirke, J. F., Sitorus, P., Inounu, I., Tiesnamurti, B., Bell, F. L., Fletcher, I. C. and Torell, D. T. 1986. Reproduction in Javanese sheep: evidence for a gene with a large effect on ovulation rate and litter size. Journal of Animal Science 63: 418–431.CrossRefGoogle ScholarPubMed
Davis, G. H., Montgomery, G. W. and Kelly, R. W. 1982. Estimates of the repeatability of ovulation rate in Booroola cross ewes. Proceedings of the 2nd World Congress on Genetics Applied to Livestock Production Vol. 5, pp. 674–679.Google Scholar
Elsen, J. M., Vu tien khano, J. and Le roy, P. 1988. A statistical model for genotype determination at a major locus in a progeny test design. Genetique, Selection et Evolution 20: 211–226.CrossRefGoogle Scholar
Elston, R. C. and Stewart, J. 1971. A general model for the genetic analysis of pedigree data. Human Heredity 21: 523–542.CrossRefGoogle ScholarPubMed
Falconer, D. S. 1989. Quantitative Genetics. 3rd ed. Longman Scientific and Technical, London.Google Scholar
Foulley, J. L. and Elsen, J. M. 1988. Posterior probability of the sire's genotype at a major locus based on progeny-test results for discrete characters. Genetique, Selection et Evolution 20: 227–238.CrossRefGoogle Scholar
Hanrahan, J. P. and Owen, J. B. 1985. Variation and repeatability of ovulation rate in Cambridge ewes. Animal Production 40: 529 (Abstr.).Google Scholar
Hanrahan, J. P. and Owen, J. B. 1989. Single gene effects on ovulation rate in Cambridge ewes. 40th Annual Meeting, European Association of Animal Production, Summaries Vol. 1, p. 65.Google Scholar
Hoeschele, I. 1988. Statistical techniques for detection of major genes in animal breeding data. Theoretical and Applied Genetics 76: 311–319.CrossRefGoogle ScholarPubMed
Jonmundsson, J. V. and Adalsteinsson, S. 1985. Simple genes for fecundity in Icelandic sheep. In Genetics of Reproduction in Sheep (ed. Land, R. B. and Robinson, D. W.), pp. 159–168. Butterworths, London.CrossRefGoogle Scholar
Lahlou-Kassi, A. and Marie, M. 1985. Sexual and ovarian function of the D'man ewe. In Genetics of Reproduction in Sheep (ed. Land, R. B. and Robinson, D. W.), pp. 245–260. Butterworths, London.CrossRefGoogle Scholar
Meat and Livestock Commission. 1989. Sheep Yearbook 1989. Meat and Livestock Commission, Bletchley.Google Scholar
Owen, J. B., Crees, S. R. E., Williams, J. C. and Davies, D. A. R. 1986. Prolificacy and 50-day lamb weight of ewes in the Cambridge sheep breed. Animal Production 42: 355–363.Google Scholar
Piper, L. R. and Bindon, B. M. 1982. Origins of the CSIRO Booroola. Proceedings of a Workshop on ‘The Booroola Merino’, Armidale, NSW, 24–25 August, 1980.Google Scholar
Piper, L. R. and Bindon, B. M. 1988. The genetics and endocrinology of the Booroola sheep F gene. Proceedings of the 2nd International Conference on Quantitative Genetics, pp. 270–282.Google Scholar
Piper, L. R., Bindon, B. M. and Davis, G. H. 1985. The single gene inheritance of the high litter size of the Booroola Merino. In Genetics of Reproduction in Sheep (ed. Land, R. B. and Robinson, D. W.), pp. 115–125. Butterworths, London.CrossRefGoogle Scholar